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Attachment of oligosaccharides to proteins is a major post-translational modification. Chemical syntheses of oligosaccharides have contributed to clarifying the functions of these oligosaccharides. However, syntheses of oligosaccharide-linked proteins are still challenging because of their inherent complicated structures, including diverse di- to tetra-antennary forms. We report a highly efficient strategy to access the representative two types of triantennary oligosaccharides through only 9- or 10-step chemical conversions from a biantennary oligosaccharide, which can be isolated in exceptionally homogeneous form from egg yolk. Four benzylidene acetals were successfully introduced to the terminal two galactosides and two core mannosides of the biantennary asialononasaccharide bearing 24 hydroxy groups, followed by protection of the remaining hydroxy groups with acetyl groups. Selective removal of one of the benzylidene acetals gave two types of suitably protected glycosyl acceptors. Glycosylation toward the individual acceptors with protected Gal-β-1,4-GlcN thioglycoside and subsequent deprotection steps successfully yielded two types of complex-type triantennary oligosaccharides.

Methylhesperidin (MHES) is a mixture of methylated derivatives of the citrus flavonoid hesperidin and is used as a food or pharmaceutical additive. Dietary MHES could be hydrolyzed by gut microflora to give aglycons. Therefore, we prepared hydrolyzed methylhesperidin (h-MHES) and assessed its pharmacological activity in human epidermal keratinocytes. h-MHES promoted nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear translocation and the expression of cytoprotective genes (e.g., heme oxygenase-1 (HO-1) and glutamate cysteine ligase catalytic subunit (GCLC)). h-MHES also increased intracellular glutathione levels and reduced UVB-induced reactive oxygen species. Moreover, h-MHES increased phosphorylation of p38 mitogen-activated protein kinase (MAPK), and a p38 MAPK inhibitor significantly attenuated h-MHES-induced HO-1 and GCLC expression. Furthermore, when we purified the components of h-MHES, we identified two methoxy-chalcones as novel Nrf2 activators. Our study demonstrates that h-MHES can induce cytoprotective gene expression and reduce oxidative stress via the Nrf2-ARE pathway in keratinocytes, suggesting that MHES may contribute to the suppression of UVB-induced skin damage in vivo.

Phthalein dyes in the quinone dianion form (pseudo-D3, colored) are transformed into the lactone dianion form (pseudo-T(d), colorless) through encapsulation in a T(d)-symmetric host even under basic conditions (pH ∼10). The compatibility in size and symmetry between the lactone and the cavity is essential to the transformation. Upon addition of a guest that strongly binds to the cavity, the encapsulated phenolphthalein is expelled, the color of the basic solution is regained, and the host-guest complexation is thus visualized.

Aromatic stacks formed through self-assembly are promising building blocks for the construction of molecular electronic devices with adjustable electronic functions, in which noncovalently bound π-stacks act as replaceable modular components. Here we describe the electron-transport properties of single-molecule aromatic stacks aligned in a self-assembled cage, using scanning probe microscopic and break junction methods. Same and different modular aromatic pairs are noncovalently bound and stacked within the molecular cage holder, which leads to diverse electronic functions. The insertion of same pairs induces high electronic conductivity (10(-3)-10(-2) G0, G0 = 2e(2)/h), while different pairs develop additional electronic rectification properties. The rectification ratio was, respectively, estimated to be 1.4-2 and >10 in current-voltage characteristics and molecular orientation-dependent conductance measurements at a fixed bias voltage. Theoretical calculations demonstrate that this rectification behavior originates from the distinct stacking order of the internal aromatic components against the electron-transport direction and the corresponding lowest unoccupied molecular orbital conduction channels localized on one side of the molecular junctions.

Proximity between a noninteractive organic substrate and a transition metal (trans-MCl2(PEt3)2; M = Pd or Pt) is achieved by their co-encapsulation within a synthetic cage, as revealed by X-ray crystallographic analysis and NOESY experiments. Through co-encapsulation with a Pd(II) complex, a terminal alkyne was activated within the cage to give a σ-alkynylpalladium complex.

Polyfluorinated aliphatic compounds were encapsulated by a self-assembled M6L4 coordination host in aqueous media. NMR titration and X-ray crystallographic analyses clearly revealed that the aggregation of the fluorinated moieties of the guests in the host cavity plays a significant role in the binding. Polyfluorinated aromatics did not show such aggregation in the cavity because of their "nonfluorous" nature.

Gastric inhibitory polypeptide (GIP), an incretin, is an important subject in endocrinology. Some LC-MS assays have been proposed; however, their sensitivities are insufficient for the study of endogenous human incretin. Here, we describe a nanoflow LC hybrid triple quadrupole/linear ion trap MS assay for the simultaneous quantification of GIP1-42 and GIP3-42 from human plasma. We selected the surrogate peptide to avoid oxidative modification, and the endoproteinase Asp-N was selected for the proteolysis of GIP1-42 and GIP3-42. The phenylalanine residue at position 6 in both GIP1-42 and GIP3-42 was substituted with (13)C9,(15)N-labeled phenylalanine, and these substituted GIPs were used as the internal standards. This facilitated accurate and precise quantification because large corrections are possible at all steps of sample pretreatment and ionization efficiency. The lower limit of quantification was 1 pM for GIP1-42 and 10 pM for GIP3-42 by using 200 μL of plasma. Quantification of GIP1-42 and GIP3-42 in plasma from patients with type 2 diabetes was possible using this method, which included protein precipitation, Asp-N proteolysis, solid-phase extraction, nanoflow LC, and positive-ion multiple reaction monitoring cubed (MRM(3)) for GIP1-8, and MRM for GIP3-8 to achieve accurate, precise, and quantitative analysis that can be validated to support large clinical trials.

The binding properties of a self-assembled coordination cage were subtly tuned by ancillary groups on the metal corners of the cage. Since the bulky mesityl groups of the ligand hang over the cage cavity, the effective cavity volume is reduced. Due to the tighter guest packing inside the shrunken cavity, smaller guests were efficiently bound and guest motion was restricted even at high temperatures.

An overcrowded alkene with an anti-folded conformation was converted to its twisted conformer, accompanied by a dramatic color change from yellow to deep purple, by inclusion in a self-assembled T(d)-symmetric coordination cage. The shape of the caged cavity was suitable and desirable for trapping of the twisted conformer. The twisted conformation was temporarily memorized in the alkene even after guest ejection. Permanent trapping of the twisted conformation was achieved by bromination of the twisted conformer formed in situ in the cage.

A cationic coordination cage dramatically accelerates the Knoevenagel condensation of aromatic aldehydes in water under neutral conditions. The addition of a nucleophile to the aldehyde to generate anionic intermediates seems to be facilitated by the cationic environment of the cavity. The products are ejected from the cage as a result of the host-guest size discrepancy. As a result, the condensation is promoted by a catalytic amount of the cage., (© 2011 American Chemical Society)

A dinuclear ruthenium complex, [(η(5)-indenyl)Ru(CO)(2)](2), was noncovalently enclathrated within a self-assembled coordination cage. In the cavity, rapid cis-trans isomerization and ligand exchange between the terminal and bridging carbonyls were suppressed, and only the carbonyl-bridged cis configuration was observed by X-ray crystallographic analysis.

Three-dimensional m × n arrays of metal ion clusters can be assembled as aromatic stacks of planar polynuclear metal complexes within columnar coordination cages. The polynuclear complexes and cage height program the final array structures of the metal ion clusters. Cyclic trinuclear Au(I) complexes (m = 3) assembled into trigonal prismatic arrays (n = 1-3) within the cages and the array structures were clearly shown by X-ray crystallographic analysis. A silver-sandwiched hetero-Au(3)-Ag-Au(3) cluster was also prepared by treating a hexanuclear Au(3)-Au(3) cluster with Ag(I) ion.

An asymmetric alignment of electron-donating (D) and accepting (A) aromatics is a formidable challenge in the self-assembly of aromatic stacks because self-assembled aromatic stacks usually give alternating aromatic arrays, D-A-D-A-.... Here, we show that appropriate D-A guest pairs settle down in an electron-deficient aromatic box to yield an asymmetric quadruple A-D-A-A stacking sequence quantitatively. The inner D-A guest pair rapidly swaps their positions to create a dynamic aromatic array, and the swift guest motion largely depends on the donor aromatics.

Despite its inertness toward pericyclic reactions under common conditions, naphthalenes readily undergo Diels-Alder reactions when coencapsulated with a suitable dienophile within the cavity of a self-assembled host. Localization of the reactant pair significantly reduces the entropic cost of the reaction, and preorganization within the host cavity controls both the regio- and stereoselectivity of the reaction: electronically disfavored exo adducts were obtained, and with substituted naphthalenes, the reaction takes place on the less electron-rich, unsubstituted ring. Our findings highlight the fact that judicious tuning of substrate size and shape within molecular flasks can unveil new and unusual reactivities for otherwise unreactive molecules.

A variety of amines including even sterically less demanding and highly nucleophilic secondary amines have been efficiently deprotected without decarboxylative N-allylation from the corresponding N-allyloxycarbonyl (N-AOC) compounds by using a catalytic amount of [CpRu(IV)(pi-C3H5)(2-quinolinecarboxylato)]PF6 in the presence of 1 molar amount of trifluoromethanesulfonic acid, the general utility of which has been demonstrated by the efficient synthesis of a collagen protein unit tripeptide, Pro-Pro-Gly.

[Reaction: see text]. The novel synthetic strategy and optical properties of highly fluorescent, triazine-amine conjugated oligomers are described herein. Under basic conditions, aromatic dinitrile compounds, NC-C6H4-X-C6H4-CN (X = NMe, O, CH2), underwent cyclic trimerization of the cyano groups at both ends to give a series of triazine-containing oligomers. The oligomers can be expressed as (2n + 1) mer, where n represents the number of triazine rings in the oligomer. The absorption maximum of an amine-conjugated trimer (X = NMe, n = 1) was outstandingly red-shifted as compared with those of the other trimers (X = CH2, O). In acidic media, the amine-conjugated trimer showed two-step bathochromic shifts caused by protonation. The absorption maxima of the amine-conjugated (2n + 1) mers (X = NMe, n = 1-4) did not depend on n; instead, shoulder peaks appeared in the long-wavelength region when n 2. The oligomers involving alternate conjugation of triazines and NMe groups through phenylene groups showed strong fluorescence in chloroform. In particular, the pentamer was the most efficient blue emitter (PhiF = 0.82). The other triazine-containing oligomers (X = CH2, O) did not show fluorescence at all. Therefore, it is concluded that the emission properties are due to the strong electron-donating and accepting abilities of the NMe and triazine moieties, respectively.

A ca. 5 nm-sized, roughly spherical hollow complex was assembled from 12 Pd2+ ions and 24 bis(4-pyridylethenyl)-substituted bent ligands. By putting a functional group at the curvature of the ligand, the 24 functional groups were precisely arrayed inward within the spherical complex. When oligo(ethylene oxide) was anchored, the void of the hollow complex was tightly filled with a pseudo poly(ethylene oxide) nanoparticle, which showed metal ion (La3+) absorption property.

The insertion of Ag(+) into NbO(2)F narrowed the band gap from 3.2 eV (NbO(2)F) to 3.0 eV (Ag-NbO(2)F), which shifted the light absorption edge from the UV light region to the near-violet light region. The photocatalytic activities of NbO(2)F and Ag-NbO(2)F were evaluated by the decomposition of gaseous 2-propanol (IPA) under 400-530 and 300-400 nm light irradiations. Ag-NbO(2)F could decompose IPA to CO(2) via acetone under both irradiation conditions. The value of the quantum efficiency was of the same order under both 400-530 and 300-400 nm light irradiations, which suggested the complete hybridization of the Ag4d and O2p orbitals in the valence band of Ag-NbO(2)F resulted in the 400-530 nm light sensitivity. The density of states calculations also supported the complete mixing of Ag4d and O2p.

This paper reports the initial process of the enzymatic degradation of solution-grown lamellar single crystals of bacterial poly[(R)-3-hydroxybutyrate] (P(3HB)) with an extracellular polyhydroxybutyrate (PHB) depolymerase purified from Alcaligenes faecalis T1. We used a hydrolytic-activity-disrupted mutant of the PHB depolymerase in order to avoid the influence of hydrolytic reaction in the system. The effect of addition of the mutant enzyme upon the P(3HB) single crystals was investigated by turbidimetric assay, high-performance liquid chromatography (HPLC), and atomic force microscopy (AFM). Suspension turbidity of the P(3HB) single crystals increased after addition of the mutant enzyme having no hydrolytic activity. No soluble product from the P(3HB) single crystals with the mutant enzyme was detected by HPLC. AFM observation of the P(3HB) single crystals adsorbed on highly ordered pyrolytic graphite revealed that the mutant enzyme yielded a lot of lengthwise crystal fragments from the P(3HB) single crystals. On the basis of these results, we concluded that the mutant enzyme disturbs the molecular packing of the P(3HB) polymer chain around the loose chain packing region in the single crystal, resulting in the fragmentation. Therefore, it is suggested that the enzymatic degradation of P(3HB) single crystals with a wild-type PHB depolymerase progresses via three steps: (1) adsorption of the enzyme onto the surface of the single crystal; (2) disturbance of the molecular packing of P(3HB) polymer chain in the single crystal by the adsorbed enzyme; and (3) hydrolysis of the disturbed polymer chain by the adsorbed enzyme.

Ca(2+)-induced complex formation between calmodulin (CaM) and mastoparanX (MasX) was studied by a fluorescence spectroscopy and by a stopped-flow method. The measurements of the fluorescence anisotropy in the presence of calcium and the fluorescence titration with Ca(2+) revealed that the N- and C-domains of CaM bound cooperatively MasX, while the tryptic fragments of CaM (TR(1)C, 1-77 and TR(2)C, 78-148) bound independently MasX. The Trp-fluorescence stopped-flow experiments revealed that the Ca(2+)-induced binding of CaM and MasX was composed of two processes: one was a rapid binding of the N-domain of CaM to MasX, which was induced by the rapid Ca(2+) binding to the N-sites of CaM. The other was a slow biphasic process. Its fast phase was the binding of the C-domain of CaM to MasX, which was induced by the slow Ca(2+) binding to the C-sites. Interestingly, the kinetics of the slow process varied with the Ca(2+) concentrations. At the low Ca(2+) concentrations, its rate constant increased to around 20 s(-1) as the Ca(2+) concentration increased. At the high Ca(2+) concentrations, the Ca(2+)-induced binding of the C-domain of CaM to MasX proceeded at a constant rate around 20 s(-1). This suggested an existence of a rate-limiting step for the Ca(2+)-induced binding of the C-domain of CaM to MasX at the high Ca(2+) concentrations. The slow phase of the slow process may be a rearrangement of the CaM-MasX complex. These results led to our model of a molecular kinetic mechanism of the Ca(2+)-induced complex formation between CaM and MasX.

A new one-dimensional (1-D) halogen-bridged mixed-valence diplatinum(II,III) compound, Pt(2)(EtCS(2))(4)I (3), has been successfully synthesized from [Pt(2)(EtCS(2))(4)] (1) and [Pt(2)(EtCS(2))(4)I(2)] (2). These three compounds have been examined using UV-visible-near-IR, IR, polarized Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray crystal structure analyses (except for 1). Compound 3 was further characterized through electrical transport measurements, determination of the temperature dependence of lattice parameters, X-ray diffuse scattering, and SQUID magnetometry. 3 crystallizes in the monoclinic space group C2/c and exhibits a crystal structure consisting of neutral 1-D chains with a repeating -Pt-Pt-I- unit lying on the crystallographic 2-fold axis parallel to the b axis. The Pt-Pt distance at 293 K is 2.684 (1) A in the dinuclear unit, while the Pt-I distances are essentially equal (2.982 (1) and 2.978 (1) A). 3 shows relatively high electrical conductivity (5-30 S cm(-1)) at room temperature and undergoes a metal-semiconductor transition at T(M-S) = 205 K. The XPS spectrum in the metallic state reveals a Pt(2+) and Pt(3+) mixed-valence state on the time scale of XPS spectroscopy ( approximately 10(-17) s). In accordance with the metal-semiconductor transition, anomalies are observed in the temperature dependence of the crystal structure, lattice parameters, X-ray diffuse scattering, and polarized Raman spectra near T(M-S). In variable-temperature crystal structure analyses, a sudden and drastic increase in the Pt-I distance near the transition temperature is observed. Furthermore, a steep increase in U(22) of iodine atoms in the 1-D chain direction has been observed. The lattice parameters exhibit significant temperature dependence with drastic change in slope at about 205-240 K. This was especially evident in the unit cell parameter b (1-D chain direction) as it was found to lengthen rapidly with increasing temperature. X-ray diffraction photographs taken utilizing the fixed-film and fixed-crystal method for the metallic state revealed the presence of diffuse scattering with line shapes parallel to the a* axis indexed as (-, n + 0.5, l) (n; integer). Diffuse scattering with k = n + 0.5 is considered to originate from the 2-fold periodical ordering corresponding to -Pt(2+)-Pt(2+)-I-Pt(3+)-Pt(3+)-I- or -Pt(2+)-Pt(3+)-I-Pt(3+)-Pt(2+)-I- in an extremely short time scale. Diffuse lines corresponding to 2-D ordering progressively decrease in intensity below 252 K and are converted to the diffuse planes corresponding to 1-D ordering near T(M-S). Furthermore, diffuse planes condensed into superlattice reflections below T(M-S). Polarized Raman spectra show temperature dependence through a drastic low-energy shift of the Pt-I stretching mode and also through broadening of bands above T(M-S).