Search

Zinc sulfide is an important wide-band gap semi-conductor and dithiocarbamate complexes [Zn(S2CNR2)(2)] find widespread use as single-source precursors for the controlled synthesis of ZnS nanoparticulate modifications. Decomposition of [Zn((S2CNBu2)-Bu-i)(2)] in oleylamine gives high aspect ratio wurtzite nanowires, the average length of which was increased upon addition of thiuram disulfide to the decomposition mixture. To provide further insight into the decomposition process, X-ray absorption spectroscopy (XAS) of [Zn(S2CNMe2)(2)] was performed in the solid-state, in non-coordinating xylene and in oleylamine. In the solid-state, dimeric [Zn(S2CNMe2)(2)](2) was characterised in accord with the single crystal X-ray structure, while in xylene this breaks down into tetrahedral monomers. In situ XAS in oleylamine (RNH2) shows that the coordination sphere is further modified, amine binding to give five-coordinate [Zn(S2CNMe2)(2)(RNH2)]. This species is stable to ca. 70 degrees C, above which amine dissociates and at ca. 90 degrees C decomposition occurs to generate ZnS. The relatively low temperature onset of nanoparticle formation is associated with amine-exchange leading to the in situ formation of [Zn(S2CNMe2)(S2CNHR)] which has a low temperature decomposition pathway. Combining these observations with the previous work of others allows us to propose a detailed mechanistic scheme for the overall process.

Resorcinarene-based deep cavitands including glutamic acid methyl resorcinarene (GMA) and glutamic acid undecyl resorcinarene (GUA) have been synthesised and their amine binding properties analysed. The cavitands are designed with hydrogen bonding groups on their upper rim (glutamic acids) and hydrophobic groups, on their lower rims. Along with the aromatic groups of the resorcinarene, these cavitands have many sites for guest binding. The cavitands form kite-like structures in dimethylsulfoxide, acetone, and water. The binding of GMA with amines, including guanidine containing drug compounds, was studied in DMSO by UV-vis titration and compared to that of phthalyl glutamic acid. The obtained binding constants for GMA to amines (K values) were in the range of 12–136 × 103 M−1 for benzyl amines and 4.3–153 × 103 M−1 for guanidine compounds. GMA shows a binding preference for more basic and less sterically encumbered amines and slightly stronger binding to S-enantiomers.

The C-X-C chemokine receptor 4 (CXCR4) has been shown to be overexpressed in at least 23 types of cancer, including prostate cancer which has been shown to have a significant distinction of expression rates between cancerous compared to healthy or benign tissue. In an attempt to exploit the difference in expression, we have synthesized a derivative of T140, a peptide antagonist for CXCR4, containing a fluorescent 4-amino-1,8-naphthalimide appended with a di-(2-picolyl)amine binding unit to chelate rhenium or technetium-99m for fluorescence or SPECT imaging. The rhenium-coordinated variant was shown to have similar binding affinity for the receptor as T140 and showed specific uptake by fluorescence microscopy in CXCR4 expressing cells. The peptide was radiolabelled with technetium-99m in decay corrected radiochemical yields ranging from 60-85%, radiochemical purities >95%, and molar activities of 36-44 GBq μmol-1. The technetium-99m labelled peptide showed two-fold higher uptake in U87 cells expressing CXCR4 compared to non-transfected cells. Ex vivo biodistribution studies were performed using the technetium-99m labelled peptide in NOD/SCID mice bearing tumors derived from U87 cells with CXCR4. Tumor uptake of 0.51 ± 0.09% ID g-1 was observed two-hours post-injection. Our novel T140 derivative is suitable for imaging of CXCR4 expression by confocal microscopy. Further structural modifications to the peptide or metal complex may result in improved biodistribution for use in SPECT imaging of CXCR4 expressing tumors.

The mechanism by which alkylamines brighten CdSe nanoparticles is investigated by transient absorption and time-resolved photoluminescence spectroscopy. The main effect of the amine is to reduce the extent of surface hole trapping, which cannot be rationalized by a model in which the amine directly binds to and thereby passivates a surface trap site. An alternative mechanism is proposed wherein the absolute energies of the valence and conduction band edges shift to more negative redox potentials upon binding of the amine. This decreases the thermodynamic driving force for hole trapping or hole transfer to an adsorbed acceptor, 4-methylbenzenethiol. Amine binding also increases the thermodynamic driving force for electron transfer to an adsorbed acceptor, methyl viologen. The rates of charge transfer to these acceptors have been measured, and the differences in the rates before and after treatment with alkylamines are consistent with the proposed mechanism.

The V27A mutation confers adamantane resistance on the influenza A matrix 2 (M2) proton channel and is becoming more prevalent in circulating populations of influenza A virus. We have used X-ray crystallography to determine structures of a spiro-adamantyl amine inhibitor bound to M2(22-46) V27A and also to M2(21-61) V27A in the Inwardclosed conformation. The spiro-adamantyl amine binding site is nearly identical for the two crystal structures. Compared to the M2 "wild type" (WT) with valine at position 27, we observe that the channel pore is wider at its N-terminus as a result of the V27A mutation and that this removes V27 side chain hydrophobic interactions that are important for binding of amantadine and rimantadine. The spiro-adamantyl amine inhibitor blocks proton conductance in the WT and V27A mutant channels by shifting its binding site in the pore depending on which residue is present at position 27. Additionally, in the structure of the M2(21-61) V27A construct, the C-terminus of the channel is tightly packed relative to that of the M2(22-46) construct. We observe that residues Asp44, Arg45, and Phe48 face the center of the channel pore and would be well-positioned to interact with protons exiting the M2 channel after passing through the His37 gate. A 300 ns molecular dynamics simulation of the M2(22-46) V27A-spiro-adamantyl amine complex predicts with accuracy the position of the ligands and waters inside the pore in the X-ray crystal structure of the M2(22-46) V27A complex.

An in situ generated Pd-Cy*Phine catalyst has been successfully applied to the N-arylation of primary and secondary amines, and it exhibited high performance across multiple substrate classes. The performance induced by the meta-terarylphosphine motif of the Cy*Phine ligand for C-N cross-coupling displayed only subtle differences to that of its biarylphosphine congener XPhos. DFT studies demonstrated comparable reaction energetics in the catalytic cycle steps for both Pd-Cy*Phine and Pd-XPhos, which was consistent with previous findings. The computational investigation also indicated that a putative rate-determining step occurred after amine binding, which was likely to have annulled the expected benefits of having a meta-terarylphosphine ligand architecture.

Solution spectroscopic investigations into the interactions of eight potential bidentate V-series organophosphorus chemical warfare agent (OP CWA) simulants with [Eu(phen)2(NO3)3]·2H2O demonstrated that the chemical and structural composition of the secondary binding site within the simulant was of paramount importance. Only simulants containing both phosphoryl/phosphonyl and amine moieties generated analogous spectroscopic behaviours to V-series OP CWAs seen in previous studies. The results demonstrated that the bidentate chelation mechanism was driven by the phosphoryl/phosphonyl moieties and that the presence of the amine moieties induced a significant secondary dynamic luminescence quenching mechanism. The binding modes of the simulants VO and TEEP to trivalent lanthanides (Eu and La) were further investigated using 1H and 31P NMR spectroscopic titrations and kinetic IR experiments. VO, with both the phosphonyl and amine binding sites was found to be the most appropriate simulant for V-series OP CWAs in supramolecular studies with trivalent lanthanide ions and we recommend VO for use in supramolecular studies of this type.

The reversible adsorption of H2S on tetraethylenepentamine (TEPA) was investigated using attenuated total reflection infrared (ATR-IR) spectroscopy, mass spectrometry, and density functional theory (DFT). The in situ infrared method revealed H2S ability to selectively poison the TEPA amine active site by the formation of a strongly adsorbed species in the form of (HS–) NH3+-TEPA. In addition, the H2S–amine interaction, in the presence of oxygen, resulted in the oxidative degradation of the amine, indicated by the formation of an −NO2 species. The addition of polyethylene glycol (PEG) affects the H2S-amine interactions and prevents the amine site from oxidative degradation. Both experimental IR and DFT calculations revealed that PEG affected the electronic and geometric environment around the amine binding site through hydrogen bonding and electron-donating effects. The addition of PEG decreased the (+) charge of the ammonium ion site, effectively decreasing electrostatic anion–cation interaction of the st...

Pendent nucleophiles are essential partners in the cleavage and formation of bonds with hydrogen (e.g. protonation/deprotonation), but binding of the pendent group to the metal and the potential trapping of complexes in inactive states are a significant problem. The dipyridylmethane-based ligand framework bis(2-pyridyl)-N-pyrrolidinomethane (R,pyrCPy2), bearing a hemilabile pyrrolidine moiety, has been synthesized and complexes of the type [(R,pyrCPy2)M(COD)]X (COD = 1,5-cyclooctadiene) were prepared. The solution-phase ligand dynamics and relative protonation preferences were investigated via1H NMR spectroscopy; although favorable, pendent amine binding does not kinetically inhibit pendent base protonation. Protonation at the metal (with concomitant pyrrolidine binding) has been found to be favorable for Ir, whereas N-protonation is favorable for Rh. DFT calculations predict that the RhIII hydrides have much higher relative acidities than their Ir congeners (ΔpKa ≃ 7–8 in CH2Cl2), and are also more acidic than the strong acid [H(OEt2)2][B(C6F5)4].

A novel heterogeneous dirhodium catalyst has been synthesized. This stable catalyst is constructed from dirhodium acetate dimer (Rh2(OAc)4) units, which are covalently linked to amine- and carboxyl-bifunctionalized mesoporous silica (SBA-15-NH2-COOH). It shows good efficiency in catalyzing the cyclopropanation reaction of styrene and ethyl diazoacetate (EDA) forming cis- and trans-1-ethoxycarbonyl-2-phenylcyclopropane. To characterize the structure of this catalyst and to confirm the successful immobilization, heteronuclear solid-state NMR experiments have been performed. The high application potential of dynamic nuclear polarization (DNP) NMR for the analysis of binding sites in this novel catalyst is demonstrated. Signal-enhanced (13)C CP MAS and (15)N CP MAS techniques have been employed to detect different carboxyl and amine binding sites in natural abundance on a fast time scale. The interpretation of the experimental chemical shift values for different binding sites has been corroborated by quantum chemical calculations on dirhodium model complexes.

In this paper we prepare three “neat” supported membranes, ZIF-8, ZIF-90, and Matrimid 5218, on porous alumina disks and compare their permeation behaviors in the separation of H2/CO2 with the corresponding zeolitic imidazolate framework (ZIF)/Matrimid mixed matrix membranes (MMMs). These MMMs consist of ZIF-8 and ZIF-90 nanoparticles which are embedded in Matrimid. We found that the embedding of the nanoparticles modifies the separation performance of the Matrimid 5218 membrane for separating H2 from CO2. TEM and SEM images of the ZIF-8 and ZIF-90/Matrimid MMMs show that the ZIFs are well embedded into the polymer. Thus, the separation behavior of these MMMs can be described with the Maxwell model. However, better separation results could be obtained by binding ZIF-90 particles covalently with ethylenediamine to the Matrimid matrix. In comparison to the MMMs that contain nonbound ZIFs, the covalent amine binding between the ZIF-90 particles and the Matrimid matrix leads to slightly lower permeabilities b...

Nitrogen containing organic compounds are very useful in industry but they often act as organic pollutants and are very difficult to selectively recover. Normal porous adsorbents such as porous organic frameworks show almost no selectivity to them because of the insensitivity between their pore size and the pollutants' molecular size. So a method of adjusting acidity was applied to modify the porous organic frameworks to enhance their selectivity to nitrogen containing organic compounds. In this research, a sulfonate grafted JUC-Z2, JUC-Z2-SO3H was prepared and exhibited high chemical stability (weight loss of 5% at 333 °C), and showed a type-I nitrogen gas adsorption/desorption isotherm. The Brunauer–Emmett–Teller surface area for this network was determined to be 1027 m2 g−1. The pore size of the JUC-Z2-SO3H, calculated by appropriate fitting of the quenched solid density functional theory model to the isotherm yielded a value of 1.0 nm. JUC-Z2-SO3H could effectively adsorb the amines better than JUC-Z2, and then JUC-Z2-SO3H could be selectively recovered and reused. Furthermore, solvents with different polarities, such as carbon tetrachloride (CCl4), ethanol and methanol, were chosen to conduct amine binding measurements with JUC-Z2 and JUC-Z2-SO3H. The formation constant Kf for JUC-Z2 and JUC-Z2-SO3H in CCl4, ethanol, and methanol drastically decreased with increasing in polarity, thus illustrating the solvent effect in amine binding. Other nitrogen containing organic compounds such as aniline, dimethylformamide, and N-methyl-2-pyrrolidone could not be adsorbed by either JUC-Z2 or JUC-Z2-SO3H.

The nuclearity and structures of the palladium complex [(SPhos)Pd(Ph)Cl]2 in the solid and solution states are revisited using a combination of Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy, NMR spectroscopy, mass spectrometry, DFT calculations and trapping experiments. The complex was tested for its catalytic activity in the coupling reaction between chlorobenzene and n-hexylamine, where different deactivation behaviours were observed in toluene, 1,4-dioxane and DMF.

The natural products isatropolone A-C (1-3) were reisolated from Streptomyces Go66, with 1 and 3 showing potent activity against Leishmania donovani. They contain a rare tropolone ring derived from a type II polyketide biosynthesis pathway. Their biosynthesis was elucidated by labeling experiments, analysis of the biosynthesis gene cluster, its partial heterologous expression, and structural characterization of various intermediates. Owing to their 1,5-diketone moiety, they can react with ammonia, amines, lysine, and lysine-containing peptides and proteins, which results in the formation of a covalent bond and subsequent pyridine ring formation. Their fluorescence properties change upon amine binding, enabling the simple visualization of reacted amines including proteins.

A range of biologically compatible, fluorescent rhenium-naphthalimide conjugates, based upon the rhenium fac-tricarbonyl core, has been synthesized. The fluorescent ligands are based upon a N-functionalized, 4-amino-derived 1,8-naphthalimide core and incorporate a dipicolyl amine binding unit to chelate Re(I); the structural variations accord to the nature of the alkylated imide with ethyl ester glycine (L(1)), 3-propanol (L(2)), diethylene glycol (L(3)), and benzyl alcohol (L(4)) variants. The species are fluorescent in the visible region between 505 and 537 nm through a naphthalimide-localized intramolecular charge transfer, with corresponding fluorescent lifetimes of up to 9.8 ns. The ligands and complexes were investigated for their potential as imaging agents for human osteoarthritic cells and protistan fish parasite Spironucleus vortens using confocal fluorescence microscopy. The results show that the specific nature of the naphthalimide structure serves to control the uptake and intracellular localization of these imaging agents. Significant differences were noted between the free ligands and complexes, with the Re(I) complex of L(2) showing hydrogenosomal localization in S. vortens.

We report the synthesis, characterization, and reactivity with H2 of a series of MnI complexes of the type [(P–P)Mn(L2)CO]+ (L2 = dppm, bppm, or (CO)2; P–P = PPhNMePPh or PPh2NBn2) that bear pendant amine ligands designed to function as proton relays. The pendant amine was found to function as a hemilabile ligand; its binding strength is strongly affected by the ancillary ligand environment around Mn. Tuning the electrophilicity of the Mn center leads to systems capable of reversible heterolytic cleavage of the H–H bond. The strength of pendant amine binding can be balanced to protect the Mn center while still leading to facile reactivity with H2. Neutral MnIH species bearing pendant amines in the diphosphine ligand were found to react with one-electron oxidants and, after proton and electron transfer reactions, regenerate cationic MnI species. The reactivity presented herein indicates that the Mn complexes we have developed are a promising platform for development of Mn-based H2 oxidation electrocatalysts.

A novel lasing “turn-on” sensory mechanism for highly sensitive vapor detection of amines is developed, utilizing a polyfluorene/palladium tetraphenylporphyrin (PFO/PdTPP) composite film as the sensing medium. A rational ratio of PdTPP could effectively quench the fluorescence of PFO via electron/energy-transfer, and the reversed electron/energy-transfer brought on fluorescence recovery once electron donating amine binding with PdTPP, which resulted in a “turn-on” lasing action under optical pump. The lasing “turn-on” action shows sensitivity more than 5 times higher compared with the spontaneous emission (fluorescence) detection. Various amines have different binding intensity with PdTPP as well as diverse fluorescence recovery features brought on the distinction of lasing thresholds and the selectivity of sensing amines. From the theoretical analysis, we could come to a conclusion that the threshold characteristic of lasing action leads to the excellent amplification of sensitivity and selectivity. The novel “turn-on” lasing sensory mechanism could be extended to other “turn-on” fluorescent sensory systems in case the used sensory materials show favorable gain features for lasing.

Hybrid Class 1/Class 2 supported amine CO2 sorbents demonstrate superior performance under practical steam conditions, yet their amine immobilization and stabilization mechanisms are unclear. Uncovering the interactions responsible for the sorbents' robust features is critical for further improvements and can facilitate practical applications. We employ solid state (29)Si CP-MAS and 2-D FSLG (1)H-(13)C CP HETCOR NMR spectroscopies to probe the overall molecular interactions of aminosilane/silica, polyamine [poly(ethylenimine), PEI]/silica, and hybrid aminosilane/PEI/silica sorbents. A unique, sequential impregnation sorbent preparation method is executed in a diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) setup to decouple amine binding mechanisms at the amine-silica interface from those within bulk amine layers. These mechanisms are correlated with each sorbents' resistance to accelerated liquid H2O and TGA steam treatments (H2O stability) and to oxidative degradation (thermal stability). High percentages of CO2 capture retained (PCR) and organic content retained (OCR) values after H2O testing of N-(3-(trimethoxysilyl)propyl)ethylenediamine (TMPED)/PEI and (3-aminopropyl)trimethoxysilane (APTMS)/PEI hybrid sorbents are associated with a synergistic stabilizing effect of the amine species observed during oxidative degradation (thermal gravimetric analysis-differential scanning calorimetry, TGA-DSC). Solid state NMR spectroscopy reveals that the synergistic effect of the TMPED/PEI mixture is manifested by the formation of hydrogen-bonded PEI-NH2···NH2-TMPED and PEI-NH2···HO-Si/O-Si-O (TMPED, T(2)) linkages within the sorbent. DRIFTS further determines that PEI enhances the grafting of TMPED to silica and that PEI is dispersed among a stable network of polymerized TMPED in the bulk, utilizing H-bonded linkages. These findings provide the scientific basis for establishing a Class 4 category for aminosilane/polyamine/silica hybrid sorbents.

A transcriptomic analysis of the saliva of T. pallidipennis together with a short proteomic analysis were carried out to reveal novel primary structures of the lipocalin/triabin protein families in this reduviid. Although triabins share some structural characteristics to lipocalins and they are classified as in the calcyn/lipocalin superfamily, triabins differ from lipocalins in the direction of β-strands in the general conformation of the β-barrel. The triabin protein family encompasses a wide variety of proteins, which disrupt the hemostasis of warm-blooded animals. Likewise, the function of proteins classified as triabins includes proteins that are carriers of small molecules, protease inhibitors, binders of specific cell-surface receptors as well as proteins that form complexes with other macromolecules. For example, triabin and pallidipin from the saliva of T. pallidipennis are thrombin and platelet aggregation inhibitors, respectively; triplatin from T. infestans binds to thromboxane A2; and nitrophorin from Rhodnius prolixus carries nitric oxide. Therefore, based on 42 new transcriptome sequences of triabins from the salivary glands of T. pallidipennis reported at present, and on triabin sequences of other American hematophagous reduviids already reported in the literature, subfamilies of triabins were proposed following phylogenetic analyses and functional characterization of triabin members. Eight subfamilies of proteins were recognized with known functions, which were the nitrophorin and amine binding proteins, Rhodnius prolixus aggregation inhibitor, triafestin, triatin, dipetalodipin and pallidipin, triplatin and infestilin, dimiconin and triabin, and procalin subfamilies. Interestingly, 70% of the analyzed sequences came from these eight subfamilies because there was no biological function associated with them, implying the existence of a vast number of proteins with potential novel biological activities.

The intermolecular hydroaminoalkylation of unactivated alkenes and vinyl arenes with secondary amines occurs readily in the presence of tantalum and niobium binaphtholate catalysts with high regio- and enantioselectivity (up to 98% ee). Mechanistic studies have been conducted in order to determine the kinetic order of the reaction in all reagents and elucidate the rate- and stereodetermining steps. The effects of substrate steric and electronic properties on the overall reaction rate have been evaluated. The reaction is first order in amine and the catalyst, while exhibiting saturation in alkene at high alkene concentration. Unproductive reaction events including reversible amine binding and arene C-H activation have been observed. The formation of the metallaaziridine is a fast reversible nondissociative process and the overall reaction rate is limited either by amide exchange or alkene insertion, as supported by reaction kinetics, kinetic isotope effects, and isotopic labeling studies. These results suggest that the catalytic activity can be enhanced by employing a more electron-deficient ligand backbone.

Modeling studies demonstrate that aryl piperazines (I), aryloxyalkylamines (II), phenylalkykamines (III) and indolylalkylamines (VI) may interact at 5-HT receptors in a similar manner. Examination of these structures (I–VI) reveals that all possess an aromatic moiety and terminal amine binding sites (Glennon et al., J Med Chem 32(8):1921–1926, 1989). In the present investigation a new series of aryloxyalkylamines (4, 5, 8, and 9) was designed and synthesized, in which the aromatic moiety is a phenyl group substituted at the 2,3-, 2,4-, 2,5-, or 2,6-positions by halogens and the terminal amine is N-methylpiperazine, or morpholine. In addition, the alkyl side chain is ethyl, or substituted ethyl at the α- or β-carbon by a methyl group. The length of the alkyl chain that separates the terminal amine from the ether oxygen atom of the aryloxy group is of major importance, and two-carbon chain appears optimal. The structures of the new compounds were assessed by microanalyses, IR, and NMR. The analgesic activity of selected compounds was performed on experimental animals and proved to be in the range of 85–100% relative to aspirin.

Eleven different organic materials were tested for their ability to remove chloride ions from an artificial seawater solution. The sweet sagewort (Artemesia annua) was found to have the highest absorption capacity and was further tested in order to determine the optimum conditions for chloride removal. Sweet sagewort is from the same Asteraceae family as the Parthenium sp. which has been shown to remove high percentages of chloride ions from artificial seawater, possibly due to its abundance of amine binding sites. An FT-IR test (Fourier Transform Infrared Spectroscopy) showed that amine groups were also present in the sweet sagewort. The sweet sagewort was able to remove 27.1% of the chloride ions at a ratio of sagewort to artificial seawater of 7 g per liter. Although Korean melon was unsuccessful at removing chloride ions, it removed copper (II) ions from water. The Korean melon was able to achieve 95% removal at a ratio of 2.5 g/L (melon/water) at pH of 7.

Despite the tremendous importance of catalysis for all types of chemistry and biochemistry, there is still a huge gap in detailed knowledge of the processes and reaction intermediates on the surfaces of the catalysts or inside. The combination of conventional and Dynamic Nuclear Polarization (DNP) enhanced solid-state NMR spectroscopy, x-ray diffraction, electron microscopy, chemical modelling and quantum chemical calculations, often loosely summarized as NMR crystallography, has evolved into one of the most powerful characterization tools to fill this gap and study solid catalysts and chemical processes on their surface or the active center of an enzyme. These techniques give an unprecedented view in the chemistry of immobilized homogeneous transition metal catalysts, supported e.g. on silica or crystalline nanocellulose (CNC) or polymer based core shell structures as carriers or reactants and reaction intermediates on transition metal nanoparticles (MNPs). The contribution presents recent examples from our group about solid-state NMR spectroscopic characterizations of mono- or binuclear Rhodium, Ruthenium and Iridium catalysts and a Nickel containing enzyme. The focus is set to the immobilization of Wilkinsons’s type catalyst and the dirhodium-acetate dimer (Rh2ac4). These are linked covalently to high-surface silica or crystalline nanocellulose support materials, employing amine, phosphine, pyridyl or carboxyl functions on the surface of the support materials or mesoporous silica supports. Combinations of 13C-, 15N-, 29Si- and 31P- CP MAS, J-resolved 31P- MAS and HETCOR solid-state NMR techniques are employed to monitor the preparation of the catalyst. Moreover, by DNP enhanced solid-state NMR it is feasible to detect different carboxyl and amine binding sites in natural abundance at a fast time scale.

We present results on the binding of a variety amines to monoligated oxidative addition complexes of the type L1Pd(Ar)Cl, where L is 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (SPhos, 1) or 2-dicyclohexylphosphino-2',4',6'-tri-ispropylbiphenyl (XPhos, 2). The binding of an amine to oxidative addition complexes composed of 1 and 2 is more complex than with smaller ligands as intermediate Pd(II) complexes with bulky biaryl phosphine ligands disfavor amine binding to favorable conformations of oxidative addition complexes. Additionally, thermodynamic and kinetic parameters for reductive elimination from complexes of the type L1Pd(amido)Ph (where amido = EtNH, Me2N, PhNH) are discussed. From this data, we suggest a possible mechanism for (biaryl phosphine) Pd-catalyzed amination reactions that is more intricate than previously thought.

To study the importance of charge–charge and cation-π interactions for the binding of positively charged amine ligands to their receptors, the energies of interaction between [(CH3)4–N]+, [(CH3)3–NH]+, and [(CH3)4–NH3]+ and acetate, as a model of Asp and Glu, and with benzene, as a model of aromatic side chains, were obtained at the MP2/aug-cc-pVDZ level of theory. The free energies of solvation in water were also calculated for the different amines. It was found that, although primary amines form stronger charge–charge interactions with acetate than tertiary or quaternary amines, the difference is not large enough to compensate their higher solvation energy. Quaternary amines show the weakest interaction with acetate. However, their alkyl groups can interact with various aromatic groups, enhancing ligand binding to the receptor. The analysis was completed with MD calculations on amine binding to the G protein-coupled receptors β2AR and CCR5. The calculations on the model systems were found to be in good agreement with the simulations of the ligand-receptor complexes.

Composites of poly(ethylenimine) (PEI) and mesoporous silica are effective, reversible adsorbents for CO2, both from flue gas and in direct air-capture applications. The morphology of the PEI within the silica can strongly impact the overall carbon capture efficiency and rate of saturation. Here, we directly probe the spatial distribution of the supported polymer through small-angle neutron scattering (SANS). Combined with textural characterization from physisorption analysis, the data indicate that PEI first forms a thin conformal coating on the pore walls, but all additional polymer aggregates into plug(s) that grow along the pore axis. This model is consistent with observed trends in amine-efficiency (CO2/N binding ratio) and pore size distributions, and points to a trade-off between achieving high chemical accessibility of the amine binding sites, which are inaccessible when they strongly interact with the silica, and high accessibility for mass transport, which can be hampered by diffusion through PEI plugs. We illustrate this design principle by demonstrating higher CO2 capacity and uptake rate for PEI supported in a hydrophobically modified silica, which exhibits repulsive interactions with the PEI, freeing up binding sites.

The widespread use of nitrogenous organic bases as environmental chemicals, food additives, and clinically important drugs necessitates precise knowledge about the molecular principles governing biotransformation of this category of substrates. In this regard, analysis of the topological background of complex formation between amines and P450s, acting as major catalysts in C- and N-oxidative attack, is of paramount importance. Thus, progress in collaborative investigations, combining physico-chemical techniques with chemical-modification as well as genetic engineering experiments, enables substantiation of hypothetical work resulting from the design of pharmacophores or homology modelling of P450s. Based on a general, CYP2D6-related construct, the majority of prospective amine-docking residues was found to cluster near the distal heme face in the six known SRSs, made up by the highly variant helices B', F and G as well as the N-terminal portion of helix C and certain beta-structures. Most of the contact sites examined show a frequency of conservation20%, hinting at the requirement of some degree of conformational versatility, while a limited number of amino acids exhibiting a higher level of conservation reside close to the heme core. Some key determinants may have a dual role in amine binding and/or maintenance of protein integrity. Importantly, a series of non-SRS elements are likely to be operative via long-range effects. While hydrophobic mechanisms appear to dominate orientation of the nitrogenous compounds toward the iron-oxene species, polar residues seem to foster binding events through H-bonding or salt-bridge formation. Careful uncovering of structure-function relationships in amine-enzyme association together with recently developed unsupervised machine learning approaches will be helpful in both tailoring of novel amine-type drugs and early elimination of potentially toxic or mutagenic candidates. Also, chimeragenesis might serve in the construction of more efficient P450s for activation of amine drugs and/or bioremediation.

We measure the conductance of amine-terminated molecules by breaking Au point contacts in a molecular solution at room temperature. We find that the variability of the observed conductance for the diamine molecule-Au junctions is much less than the variability for diisonitrile and dithiol-Au junctions. This narrow distribution enables unambiguous conductance measurements of single molecules. For an alkane diamine series with 2-8 carbon atoms in the hydrocarbon chain, our results show a systematic trend in the conductance from which we extract a tunneling decay constant of 0.91 +/- 0.03 per methylene group. We hypothesize that the diamine link binds preferentially to undercoordinated Au atoms in the junction. This is supported by density functional theory-based calculations that show the amine binding to a gold adatom with sufficient angular flexibility for easy junction formation but well-defined electronic coupling of the N lone pair to the Au. Therefore, the amine linkage leads to well-defined conductance measurements of a single molecule junction in a statistical study.

New approaches are constantly being developed for both the synthesis of inorganic nanomaterials and their surface modification for sensing and electronic applications. Insofar as surface modification of gold nanoparticles is concerned, thiol chemistry is the most popular approach to bind ligands to their surface. We have been pursuing the possibility of using amine functionality to bind ligands to the surface of gold nanoparticles and have found that amine binding is as strong as thiol binding. The advantages of using amine chemistry for surface modification of nanogold are many, the possibility of complexing a large variety of biomolecules such as amino acids and proteins being one of the most important. In this article, we review the work from this laboratory on the stabilization of gold nanoparticles using amino acids as well as using amino acids as reducing agents to obtain stable aqueous solutions of gold nanoparticles of variable size. We also discuss the possibility of forming bioconjugates of enzymes with gold nanoparticles decorating the surface of polymer microspheres and their application as reusable biocatalysts. There is much to be gained by marrying nanomaterials with biology with considerable spin-offs likely in both nanotechnology and biotechnology.

The subcommissural organ (SCO) is a brain gland that secretes glycoproteins into the cerebrospinal fluid (CSF), where they subsequently aggregate to form Reissner fiber (RF). By addition of newly released glycoproteins to its cephalic end, RF grows constantly through the Sylvian aqueduct, fourth ventricle and central canal of the spinal cord. Disaggregation of RF-material and passage to blood occur when RF reaches the terminal ventricle at the filum. The present investigation was designed to test the hypothesis that RF binds, transports and clears away monoamines present in the CSF. Four experimental protocols were applied: (i) in vivo binding of labeled monoamines to the rat RF, studied by pulse and chase, and after perfusion for 7 days; (ii) identification of monoamines, by high-performance liquid chromatography (HPLC), naturally occurring in the bovine RF; (iii) in vitro binding of labeled and unlabeled monoamines to the isolated bovine RF; and (iv) tentative identification of the amine binding site(s) in RF-proteins by use of specific antibodies. The results obtained indicate that RF participates in the regulation of the CSF concentration of monoamines either by binding and transporting them away throughout the central canal of the spinal cord (L-DOPA, noradrenaline, adrenaline), or by transiently binding them and releasing them back to the CSF (serotonin). Furthermore, evidence was obtained that (i) adrenaline and noradrenaline share the same binding site, and that this site would correspond to a repeated sequence present in the SCO-spondin, the major protein component of RF; and (ii) serotonin has its own binding site in RF.

1 H NMR spectroscopic studies of amino ester complexation indicate that iodorhodium(III) tetramethylchiroporphyrin RhI(TMCP) has a single axial site available for the coordination of amine groups, and that it retains its iodo ligand trans to the coordinated amine. This conclusion is confirmed by the X-ray structure of the 1:1 adduct of n-propylamine with RhI(TMCP). This stoichiometry of amine binding makes RhI(TMCP) a superior chiral derivatizing agent relative to CoCl ( TMCP ), which gives 1:2 adducts. It may have a strong impact in the utilization of RhI(TMCP) for the enantiomeric assay of amino acid mixtures by 1 H NMR spectroscopy. Axial exchange of the (R)- and (S)-enantiomers of aspartic acid dimethyl ester on RhI(TMCP) is moderately slow, and equilibrium is reached in a few minutes without kinetic resolution.

Surface molecularly imprinted polypropylene-based fibers for specifically recognizing bisphenol A (BPA-MIF) have been prepared through non-covalent surface molecular imprinting and self-assembly post-polymerization techniques. Acrylic acid (AA) was grafted onto pre-irradiated polypropylene (PP) fiber, and then polyethyleneimine (PEI) was assembled onto the AA grafted fiber surface to introduce amine groups for binding BPA templates from its aqueous solution. The imprinted binding sites were stabilized by cross-linking with glutaraldehyde in the presence of BPA templates. The Scatchard analysis indicated that two classes of amine binding sites were formed in the imprinted fiber BPA-MIF. The maximum adsorption capacity and association constant were 85.9 μmol/g and 56.1 μmol/L, respectively. The selectivity of BPA-MIF fibers for BPA against its analogues was obviously increased by adopting the surface molecular imprinting technique. In this work, a new path was given for the preparation of molecular imprinting materials in water system for other toxics with low solubility in aqueous solution.

Molecularly imprinted films of poly(acrylic acid) (PAA) have been coated onto n-CdSe in order to make the band-edge photoluminescence (PL) of the semiconductor respond selectively to the imprinting analyte. This strategy has been implemented using PAA films deposited in the presence of ammonia and trimethylamine analytes. PAA films have been characterized by IR spectroscopy, which indicates that binding of either analyte nearly reversibly deprotonates the polymer carboxylic acid groups. PL measurements suggest that the imprinted PAA coatings serve as sieves for selective surface binding: In contrast to the bare CdSe surface, which responds both to ammonia and trimethylamine with reversible enhancements in PL intensity, CdSe coated with ammonia-imprinted PAA (AI−PAA) films exhibits reversible PL changes toward ammonia but no response to trimethylamine. The PL changes for the AI−PAA films can be fit to a dead-layer model that indicates that ammonia binding reduces the CdSe depletion width by ∼100 A, an eff...

This study investigates the effect of deacetylation degree and molecular weight of chitosan on molybdate sorption on both raw and glutaraldehyde crosslinked samples. It appears that the physicochemical parameters affect the crystallinity of the samples: a high crystallinity reduces the accessibility of both water and metal ions to the amine binding sites. Both equilibrium and kinetic performances are thus influenced. The crosslinking by glutaraldehyde decreases sorption performances for large size particles while it does not influence sorption for the smallest. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 571–580, 1998

Photosynthetic water oxidation occurs at the Mn-containing catalytic site of photosystem II (PSII). By the use of 14 C-labeled amines and SDS-denaturing PAGE, covalent adducts derived from primary amines and the PSII subunits, CP47, D2/D1, and the Mn-stabilizing protein, can be observed. When PSII contains the 18- and 24-kDa extrinsic proteins, which restrict access to the active site, no 14 C labeling is obtained. NaCl, but not Na 2 SO 4 , competes with 14 C labeling in Mn-containing PSII preparations, and the concentration dependence of this competition parallels the activation of oxygen evolution. Formation of 14 C-labeled adducts is observed in the presence or in the absence of a functional manganese cluster. However, no significant Cl − effect on 14 C labeling is observed in the absence of the Mn cluster. Isolation and quantitation of the 14 C-labeled aldehyde product, produced from [ 14 C]benzylamine, gives yields of 1.8 ± 0.3 mol/mol PSII and 2.9 ± 0.2 mol/mol in Mn-containing and Mn-depleted PSII, respectively. The corresponding specific activities are 0.40 ± 0.07 μmol(μmol PSII-hr) −1 and 0.64 ± 0.04 μmol(μmol PSII-hr) −1 . Cl − suppresses the production of [ 14 C]benzaldehyde in Mn-containing PSII, but does not suppress the production in Mn-depleted preparations. Control experiments show that these oxidation reactions do not involve the redox-active tyrosines, D and Z. Our results suggest the presence of one or more activated carbonyl groups in protein subunits that form the active site of PSII.

Peptide sequence analysis and cDNA cloning indicate that a previously described mouse arginine-specific dibasic cleaving enzyme (dynorphin converting enzyme) [Csuhai et al. (1995) Biochemistry 34, 12411] is the homologue of N-arginine dibasic convertase (NRDc) isolated from rat testis [Chesneau et al. (1994) J. Biol. Chem. 269, 2056]. A mouse NRDc cDNA exhibited 98% amino acid identity with the rat cDNA. However, within a 74 residue acidic stretch, this identity drops to 82%. Likewise, the corresponding acidic stretch of human NRDc is only 73% identical with that of rat NRDc. To reconcile previously observed kinetic differences between rat and mouse NRDc, the hydrolysis of peptide substrates by the rat, human, and mouse enzymes was compared using phosphate and Tris as buffers. Although the three NRDc's behaved similarly, Tris had a pronounced effect on the kinetics of peptide hydrolysis. With BAM-8, alpha-neoendorphin, and dynorphin B as substrates, Tris increased KM up to 40-fold with little change in Vmax, while with dynorphin A or somatostatin 28 as substrate, Tris caused a decrease in KM of up to 100 fold, again with only a modest change in Vmax. Other amines, including the polyamines putrescine, spermidine, and spermine, all affected NRD convertase activity. It is proposed that amines bind to the acidic stretch found in NRDc, and that quantitative differences in the sensitivity to amines between the rat, mouse, and human enzymes can be at least partially accounted for by differences in their acidic stretch. The role of polyamines as physiological modulators of N-arginine dibasic convertase is considered.

This paper reports a convenient, one-pot, easily scalable and readily modifiable synthesis of a novel large-ring bis(1,10-phenanthrolinyl-2,5-pyrrole) macrocycle, H2LMC, and describes its spectroscopic and electrochemical properties, protonation, cooperative amine binding, electrocatalysis of the oxidation of primary amines, photosensitization of the decomposition of dichloromethane, and the first lanthanide complexes of the hexaaza-dianion LMC(2-) including the novel dimer, [(NO3)(LMC)Eu(μ-OH)Eu(LMC )(H2 O)2]·2py.

An enzymatic fraction (PPE) obtained by selective precipitation from a pea seedling extract was shown to catalyze putrescine incorporation. In order to elucidate the type of enzyme, transglutaminases or diamine oxidases (DAO), involved in this activity, the ability of this PPE fraction to catalyze their characteristic reactions, amine binding, deamidation, protein cross-linking, and oxidation was investigated. The use of specific enzyme inhibitors pointed out that only DAO was present in the extract and should be involved in the protein cross-linking reactions. This reaction was only catalyzed in the presence of diamines, especially putrescine and cadaverine, or polyamine like spermidine. Keywords: Guinea pig liver transglutaminase; pea seedling diamine oxidase; amine binding; cross-linking; deamidation; Pisum sativum

The catalytic photocleavage of CS(2) to S(8) and a (C(x)S(y))(n) polymer with visible light using a dinuclear ruthenium(II) compound with a bipyridine units for photoactivity and a vicinal tertiary amine binding site for CS(2) activation was studied. The catalyst was characterized by X-ray diffraction, (1)H NMR, and (13)C NMR, ESI-MS and elemental analysis. CS(2) photocleavage was significant (240 turnovers, 20 h) to yield isolable S(8) and a (C(x)S(y))(n) polymer. A mononuclear catalyst or one without an amine binding site showed significantly less activity. XPS of the (C(x)S(y))(n) polymer showed a carbon/sulfur ratio ∼1.5-1.6 indicating that in part both C-S bonds of CS(2) had been cleaved. Catalyst was also included within the polymer. The absence of peaks in the (1)H NMR verified the (C(x)S(y))(n) nature of the polymer, while (13)C NMR and IR indicated that the polymer had multiple types of C-S and C-C bonds.

Factor XIIIa is a transglutaminase that catalyzes intermolecular gamma-glutamyl-epsilon-lysyl bonds between fibrin and other proteins involved in hemostasis. We synthesized 25 peptides from various regions of factor XIIIa and studied their effects on cross-linking fibrin, N,N'-dimethylcasein, or fibronectin. We found that two peptides, Asn72-Asp97 (peptide-4) and Asp190-Phe230 (peptide-7), inhibited factor XIIIa cross-linking of these substrates. The other peptides did not inhibit factor XIIIa activity. The inhibition of cross-linking was reversed by excess substrate, indicating that the peptides were interacting with fibrin and not factor XIIIa. The peptides were not pseudosubstrates since they were not cross-linked to fibrin. The peptides did not modify the primary amine binding site as increasing the primary amine concentration did not reverse inhibition. Peptides-4 and -7 also had no effect on exposure of the active site of factor XIIIa and no synergistic inhibitory effects were detected. Peptides-4 and -7 had no effect on factor XIIIa binding to fibrin suggesting that the binding sites and the substrate recognition sites were distinct. Synthetic peptides containing shorter amino acid sequences of peptide-4 were inactive. In contrast, the amino-terminal (Asp190-Lys199, Tyr194-Tyr204) and the carboxyl-terminal (Lys221-Phe230) portions of peptide-7 were 20-60-fold less inhibitory compared to intact peptide-7. Peptides-4 and -7 also inhibited guinea pig liver tissue transglutaminase from cross-linking fibrinogen, N,N'-dimethylcasein, and fibronectin. In conclusion, we have identified two regions outside the active site pocket which are important for substrate recognition in factor XIIIa and tissue transglutaminase.

Methods have been developed for the preparation of 2-(2(RS)-aminopropyl)-5-iodothiophenes. The syntheses and physical properties of 2-(2(RS)-aminopropyl)-5-iodothiophene and N-isopropyl-2-(2(RS)-aminopropyl)-5-iodothiophene are described. The radioiodinated agents are of interest because of the high expected uptake and prolonged brain retention that may result from binding to high-capacity, relatively nonspecific amine binding sites. Radioiodine was introduced into the 5-position of 2-(2(RS)-aminopropyl)-5-iodothiophene and N-isopropyl-2-(2(RS)-aminopropyl)-5-iodothiophene by radioiodination of the corresponding 5-boronic acid or 5-(trimethylstannyl) derivatives. Tissue distribution studies in rats with 2-(2(RS)-aminopropyl)-5-[125I]iodothiophene showed high brain uptake (5 min, 2.77% dose/g; 30 min, 2.51% dose/g) and good brain/blood (B/B) ratios (5 min, 6/1; 30 min 3.8/1. A comparison of the brain uptake of the N-isopropyl derivative with the 2(RS)-aminopropyl analogue demonstrated higher initial brain uptake and brain to blood ratios (5 min, 3.2% dose/g; 10.3/1) but more rapid washout (30 min, 1.37% dose; 2.8/1). These data suggest that radiolabeled 2-(2(RS)-aminopropyl)-5-iodothiophenes are potentially useful agents for cerebral perfusion imaging by single-photon-emission computerized tomography (SPECT).

Ion binding followed rapidly by occlusion is a mechanism utilized by the Na,K-ATPase and many P-type ATPases to minimize futile ATP hydrolysis cycles during transport. Enzyme conformations associated with ion occlusion are relatively stable from a thermodynamic standpoint as ion occluded states of the enzyme can be maintained for extended periods under the appropriate conditions (1–3). Ion bound but not occluded states of the enzyme, on the other hand, appear to be unstable and have been more difficult to study (4). Nonetheless, Forbush (3) showed that release of the K+ congener, Rb+, from the ion-occluded enzyme occurred by a sequential, ordered reaction, in agreement with data from Glynn et al. (2). Likewise, the kinetics of extracellular Na+ binding and occlusion reactions also suggested that binding and release of this ion occurs as an ordered series of diffusion-limited binding reactions separated by protein conformational rearrangements (5). Even so, to gain a greater understanding of how the Na,K-ATPase functions in its capacity as an ion transporter, it would be advantageous to study ion binding reactions in more detail and separate from the associated conformational changes that lead to ion occlusion. One obvious reason to separate ion binding from subsequent reactions would be to answer unambiguously the question of how the membrane electric field affects ion transport. Ion binding kinetics are influenced by electric field strength (5). The problem with previous studies is that ion binding cannot be separated from subsequent enzyme conformational changes. Secondly, the ability to study ion binding independently of occlusion should open the door to more detailed studies of the factors affecting ion binding reactions. Forbush (6) previously suggested that ion binding reactions of the Na,K-ATPase could be studied with an enzyme inhibitor that interacted with ion binding sites without becoming occluded. His work suggested that organic quaternary ammonium ions could be such inhibitors; however, this conclusion was based on assumptions about how quaternary amines inhibit the Na,K-ATPase. Should these assumptions be confirmed experimentally, these compounds might prove to be valuable tools to further study ion binding by the Na,K-ATPase. Organic quaternary amines competitively inhibit extracellular K+ and Rb+ activation of ion transport by the Na,K-ATPase (7–10). Tetraethylammonium ion (TEA) has been shown to inhibit ion transport by the Na,K-ATPase in this fashion (7,9,11). Measurements of Na,K-pump current in the presence of TEA have also shown that this quaternary amine inhibits the Na,K-ATPase in a membrane potential (VM)-independent manner (9,11), i.e. irrespective of VM, inhibition decreases the apparent affinity for extracellular K+ (K+o) activation of Na,K-pump current by a similar degree (see eq. 2 in Peluffo et al. (9)). The VM independence of Na,K-pump current block by TEA leads one to the conclusion that, although TEA competes with K+o, the amine does not inhibit the enzyme at K+o binding sites because K+o dissipates 30–40 % of the membrane electric field as it binds and activates Na,K-ATPase turnover (9,12–14). Even though the relationship between electrical and physical distances in the enzyme is not known, it seems reasonable to suppose that TEA, which has the same charge and is approximately the same size of a K+ ion with a single hydration shell, would dissipate a similar fraction of the membrane electric field if it inhibited the enzyme at the same site where K+ binding occurs. Thus, like cardiac glycosides (15), TEA inhibition of the Na,K-ATPase is competitive with K+ but might reflect interaction of the blocker with a site or enzyme conformation other than that for K+ binding, as noted by Kropp and Sachs (8) for another quaternary amine, tetrapropylammonium ion. For this reason, TEA inhibition of Na,K-pump current, while interesting, would only provide limited information about ion binding and transport by the Na,K-ATPase. The benzylic analogue of TEA, benzyltriethylammonium ion (BTEA), has also been shown to inhibit Na,K-pump current in a manner that is competitive with K+o activation (9) and slow release of 86Rb+ occluded by the Na,K-ATPase (6). However, BTEA inhibits Na,K-pump current in a VM-dependent manner. Specifically, BTEA appears to produce greater current block at more negative VM. Furthermore, the fraction of the membrane electric field dissipated during BTEA inhibition is similar to the fraction of the electric field dissipated during K+o activation of ion transport (9). In other words, the binding sites for BTEA and K+ in the Na,K-ATPase appear to have similar electrical properties. Given the competitive nature of the BTEA and K+ interaction, a reasonable conclusion is that BTEA inhibits the Na,K-ATPase at or near a K+ binding site responsible for stimulating enzyme turnover (9). If this conclusion is correct, BTEA or similar compounds might become valuable probes to understand K+ binding reactions by the Na,K-ATPase and possibly as leading compounds to develop novel inhibitors of this enzyme. Should the Na,K-ATPase be unable to occlude BTEA or similar compounds, they would be the first probes to allow investigation of VM-dependent ion binding, distinct from subsequent occlusion and transport reaction steps by the Na,K-ATPase. In that case, one prediction is that a compound undergoing VM-dependent ion binding should produce movement of charge in the membrane electric field. These charge movements should only be seen under pre-steady state conditions, analogous to electroneutral K+-K+ exchange conditions in which Tl+o-dependent transient charge movements have been observed previously (12). Nonetheless, a critical distinction should exist between charge movements produced by BTEA-like compounds and those produced by Tl+ and other transported ions, such as K+ and Na+. Movement of Tl+ in the electric field is thought to be diffusion limited, so that the rate of transient charge movements reflects kinetics of slow enzyme conformational changes subsequent to ion binding (5, 12, 16,17). By comparison, if not occluded, quaternary amines would yield measurable charge movements whose rates would reflect kinetics of binding that are not diffusion-limited. The experiments in this report were therefore undertaken to test these predictions and derive information regarding ion binding reactions from such charge movements. The first high resolution structure for the Na,K-ATPase has been published (18). Nonetheless, our understanding of the conformational changes that accompany ion transport by P-type ATPases relies largely on structures for SERCA (19–21). To see if quaternary amines inform us about extracellular ion binding reactions by the Na,K-ATPase, amine binding to Na,K-ATPase was simulated with homology models, based on SERCA (22). The results of these simulations suggest why some quaternary amines inhibit the Na,K-ATPase in a VM-dependent manner. Portions of this work have appeared previously in abstract form (23–26).

The array CGH technique (array comparative genome hybridization) has been developed to detect chromosomal copy number changes on a genome-wide and/or high-resolution scale. Here, we present validated protocols using in-house spotted oligonucleotide libraries for array CGH. This oligo array CGH platform yields reproducible results and is capable of detecting single copy gains, multicopy amplifications as well as homozygous and heterozygous deletions with high resolution. The protocol allows as little as 300 ng of input DNA, which makes the procedure valuable for small clinical samples and is also functional for DNA samples obtained from archival tissues.

Array-based comparative genomic hybridization is a high resolution method for measuring chromosomal copy number changes. Here we present a validated protocol using in-house spotted oligonucleotide libraries for array comparative genomic hybridization (CGH). This oligo array CGH platform yields reproducible results and is capable of detecting single copy gains, multi-copy amplifications as well as homozygous and heterozygous deletions as small as 100 kb with high resolution. A human oligonucleotide library was printed on amine binding slides. Arrays were hybridized using a hybstation and analysed using BlueFuse feature extraction software, with >95% of spots passing quality control. The protocol allows as little as 300 ng of input DNA and a 90% reduction of Cot-1 DNA without compromising quality. High quality results have also been obtained with DNA from archival tissue. Finally, in addition to human oligo arrays, we have applied the protocol successfully to mouse oligo arrays. We believe that this oligo-based platform using ‘off-the-shelf’ oligo libraries provides an easy accessible alternative to BAC arrays for CGH, which is cost-effective, available at high resolution and easily implemented for any sequenced organism without compromising the quality of the results.

pi-Conjugated oligo(p-phenylene vinylene) (OPV) guest molecules for interaction with dendritic hosts were synthesized and fully characterized by NMR spectroscopy, MALDI-TOF-MS, elemental analysis and optical measurements. The binding properties of the five different OPV guests to a N,N-bis[(3-adamantyl ureido) propyl] methylamine host have been investigated. The guests that contained an aryl urea glycine spacer were bound with the highest association constant. Subsequently, an adamantyl urea modified fifth generation poly(propylene imine) dendrimer was synthesized as a multivalent host which contains 32 N,N-bis[(3-adamantyl ureido) propyl] amine binding sites. Size exclusion chromatography showed that 32 of the OPV guests strongly bind to the fifth generation adamantyl functionalized dendritic host. In the case of the supramolecular dendritic host/guest system smooth homogeneous thin films could be obtained by spin coating. The dendritic guest-host complexes showed a significantly higher emission upon binding then that of the individual molecules due to the three-dimensional orientation of the OPV guest molecules. In the solid state, this enhancement in luminescence was a factor of 10. The pi-conjugated oligomers are less aggregated in the supramolecular assemblies presumably because of a shielding effect of the bulky adamantyl units present in the hosts.

The H64D/V68A and H64D/V68S mutants of Myoglobin are found to oxidize thioanisole with high enantioselectivity and reactivity. These mutants are also capable of enantioselective binding of alpha-methylbenzylamine, which mimics an expected sulfoxidation intermediate. The kinetic study of the amine binding shows that the Fe-O bond cleavage in the intermediate may be the chiral discrimination step of the sulfoxidation.

Von Willebrand disease (VWD) is a common bleeding disorder characterized by defects in the interaction of von Willebrand factor (VWF) with its ligands factor VIII, platelet glycoprotein Ib, and/or collagen. Nearly all assessment of collagen binding is performed with types I or III collagen. Type VI collagen, which is formed as a tight triple helix, has also been reported to interact with VWF. In contrast, type IV collagen lacks this tight helical structure and is located in the basal lamina. Type IV collagen may therefore serve as another important ligand for VWF. We examined this interaction in samples from the Zimmerman Program for the Molecular and Clinical Biology of VWD, a large US study of subjects with all types of VWD. Subjects were enrolled based on a pre-existing diagnosis of VWD and compared to a cohort of healthy controls. VWF antigen (VWF:Ag), VWF ristocetin cofactor activity (VWF:RCo), and type III collagen binding using 1 mcg/mL human placental type III collagen (VWF:CB3) were performed in the clinical laboratory at the BloodCenter of Wisconsin. Type IV and type VI collagen binding (VWF:CB4 and VWF:CB6) were performed in the research laboratory by ELISA using 1 mcg/mL human placental type IV or type VI collagen captured on amine binding plates. DNA sequencing was performed on all subjects to identify VWF sequence variations. Bleeding scores were calculated according to the scoring system used in the MCMDM-1VWD study. For this analysis, 251 healthy controls, 535 type 1, 49 type 2A, 16 type 2B, 18 type 2M, 11 type 2N, and 18 type 3 VWD were included. The mean VWF:CB4/VWF:Ag ratio for the healthy controls was 0.96, with a standard deviation of 0.24. This was similar to the mean VWF:CB6/VWF:Ag ratio (mean 0.95, p=NS), but slightly lower than the mean VWF:CB3/VWF:Ag ratio (mean 1.05, p Mean VWF:CB4/VWF:Ag ratios were low for both type 2A and type 2B VWD subjects, at 0.54 and 0.52 respectively. This was not significantly different from the VWF:CB3/VWF:Ag data (p=NS for both type 2A and 2B VWD), consistent with the loss of high molecular weight multimers in these subjects and the concomitant reduction in collagen binding. As expected, VWF:CB4/VWF:Ag ratios were normal in the type 2N subjects, with a mean of 1.04. The type 2M subjects, however, displayed a significant reduction in type IV collagen binding, with a mean VWF:CB4/VWF:Ag ratio of 0.79. One subject with an 11 amino acid deletion (from p.R1392 through p.Q1402) had absent binding to type IV collagen yet normal binding to type III collagen with a VWF:CB3/VWF:Ag ratio of 0.82. Another subject with p.I1425F and p.R1399H had a VWF:CB4/VWF:Ag ratio of 0.48, and VWF:CB3/VWF:Ag ratio of 1.10. Type IV collagen binding did not correlate with VWF:RCo (R squared less than 0.1). The type 2M subjects with a mean VWF:CB4/VWF:Ag ratio less than 0.7 had higher bleeding scores, with a mean bleeding score of 9 compared to a mean of 6 for type 2M subjects with a mean VWF:CB4/VWF:Ag ratio greater than 0.7. Not surprisingly, the subjects with type 3 VWD and undetectable VWF:Ag also had undetectable VWF:CB4. These data suggest that type IV collagen binding reflects an independent function of VWF apart from platelet binding, and distinct from binding to type III collagen. In our study, more variation was seen between type IV and type III collagen than between type IV and type VI collagen. Neither VWF:CB4 nor VWF:CB6 are currently tested as part of the clinical workup of VWD. Measurement of this function may assist in identification of variant VWD, particularly in the subgroup of patients with type 2M VWD. Disclosures: No relevant conflicts of interest to declare.

The molecular components ensuring the strict exopeptidase action of aminopeptidase N (APN) and related zinc aminopeptidases of the M1 family have not yet been clearly established. The specific recognition of the N-terminal amino acid of the substrates by the enzymes has been proposed to involve either the complexation of the free amino group by the catalytic zinc ion or an interaction with an anionic binding site, which could be constituted by an aspartate or glutamate residue. To investigate the existence of such an ionic binding site, site-directed mutagenesis experiments have been performed on acidic residues of pig APN. Given that aminopeptidases of the M1 family are likely to have a common mechanism of action, only strictly conserved residues were mutated. As compared to the wild-type enzyme, the mutation D220E led only to slight modifications in the kinetic parameters of the enzyme and in the Ki values of various inhibitors, indicating that this residue is not critically involved in the hydrolytic mechanism. In contrast, the mutations E350Q and E350D induced a large decrease in enzyme activity, essentially due to modifications in kcat, whereas the E350A mutation led to an almost completely inactive enzyme. Moreover, among the inhibitors tested, only those acting as transition state analogs showed significant increases in their Ki values. These data are in favor of E350 belonging to the "anionic binding site" in APN. A mechanism of action, derived from that of thermolysin, is proposed for these aminopeptidases, which explains the importance of E350 in transition state formation, rather than in the Michaelis complex.

We report the discovery that high-TC ferromagnetism in manganese-doped ZnO (Mn2+:ZnO) can be activated by amine binding and calcination. The activation of ferromagnetism is attributed to the incorporation of uncompensated p-type dopants into the ZnO lattice upon amine calcination, a process that has substantial precedence in the literature surrounding p-type ZnO. The experimental observations are consistent with a microscopic mechanism involving formation of bound magnetic polarons upon introduction of p-type dopants into Mn2+:ZnO. These results clearly demonstrate that Mn2+:ZnO ferromagnetism is critically sensitive to defects other than the magnetic dopants themselves, offering some insight into the diversity of experimental observations reported previously for this material.