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Samples were obtained from two world-famous 17th century panel paintings of the Gdańsk school of panting: 'Seven Acts of Charity' (1607, in St. Mary's Church in Gdańsk, Poland) by Anton Möller and 'Angelic Concert' (1611, in Diocesan Museum in Pelplin, Poland) by Hermann Han. Micro-Raman spectroscopy (MRS), optical microscopy (OM), and X-ray fluorescence (XRF) spectroscopy studies of the samples were performed to characterize the pigments present in the individual painting layers (a rich palette of white, black, blue, red, and yellow pigments) and the pictorial techniques used by the artists., (Copyright © 2014 Elsevier B.V. All rights reserved.)

In this paper, we present spectroscopic studies of neuropeptide Y (NPY) and its native NPY(3-36), NPY(13-36), and NPY(22-36) and mutated acetyl-(Leu(28,31))-NPY(24-36)C-terminal fragments acting on Y2 receptor. Since there is some evidence for the correlation between the SERS patterns and the receptor binding ability, we performed a detailed analysis for these compounds at the metal/water interface using Raman spectroscopy (RS) and surface-enhanced Raman spectroscopy (SERS) methods. Many studies have suggested that interactions of this kind are crucial for a variety of biomedical and biochemical phenomena. The identification of amino acids in these peptide sequences by SERS allowed us to determine which molecular fragments were responsible for the interaction with the silver nanoparticle surface. Our findings demonstrated that in all of the investigated compounds, the NPY(32-36)C-terminal fragment (Thr(32)-Arg(33)-Gln(34)-Arg(35)-Tyr(36)NH2) was involved in the adsorption process onto metal substrate. The results of the present study suggest that the same molecular fragment interacts with the Y2 receptor, what proved the usefulness of the SERS method in the study of these biologically active compounds. The search for analogs acting on Y2 receptor may be important from the viewpoint of possible future clinical applications., (Copyright © 2014 Elsevier Inc. All rights reserved.)

This work presents near-infrared Raman spectroscopy (FT-RS) and surface-enhanced Raman scattering (SERS) studies of three pyridine-α-hydroxymethyl biphenyl phosphine oxide isomers: (diphenylphosphoryl)(pyridin-2-yl)methanol (α-Py), (diphenylphosphoryl)(pyridin-3-yl)methanol (β-Py), and (diphenylphosphoryl)(pyridin-4-yl)methanol (γ-Py) adsorbed onto colloidal and roughened in oxidation-reduction cycles silver surfaces. The molecular geometries in the equilibrium state and vibrational frequencies were calculated by density functional theory (DFT) at the B3LYP 6-311G(df,p) level of theory. The results imply that the most stable structure of the investigated molecules is a dimer created by two intermolecular hydrogen bonds between the H atom of the α-hydroxyl group (in up (HOU) or down (HOD) stereo bonds position) and the O atom of tertiary phosphine oxide (═O) of the two monomers. Comparison the FT-RS spectra with the respective SERS spectra allowed us to predict the orientation of the hydroxyphosphonate derivatives of pyridine that depends upon both the position of the substituent relative to the ring N atom (in α-, β-, and γ-position, respectively) and the type of silver substrate.

This work presents adsorption geometry of [N-butyl-guanidino-(4-bromophenyl)methyl] phosphonic acid (4-BrPhG(n-But)P) on different SERS-active substrates (colloidal and specifically prepared Ag and Au roughened substrates). The adsorption mode is deduced from the SERS selection rules and several characteristic bands of the 4-BrPhG(n-But)P molecular fragments. The SERS spectra are compared to the experimental FT-Raman spectrum. In addition, the vibrational wavenumbers and PED's obtained for 4-BrPhG(n-But)P by using density functional theory methods with B3LYP/6-311++G(**) level of theory and PCM model is briefly presented., (Copyright © 2013 Elsevier B.V. All rights reserved.)

In this work, we developed a new method to prepare porous PA6 with different morphologic feature and crystalline forms via the decomplexation of PA6/CaCl2 composite. The structures and morphology of thus obtained materials were characterized by vibrational spectroscopy (FT-IR and Raman) and scanning electron microscope (SEM) method. When amorphous PA6/CaCl2 composite films were treated in water at room temperature, PA6 re-arranges into γ form. However, decomplexation of the PA6/CaCl2 composite in boiling water produces PA6 in α crystalline form. If the PA6/CaCl2 composite is soaked in methanol, part of PA6 is dissolved or swollen in methanol/metal salt solutions. As a result, a dissolve/precipitation process occurred during the decomplexation process, which led to the formation of PA6 in α crystalline form. Further investigation demonstrates that the morphologies of the porous PA6 could be adjusted by using different solvents and/or different decomplexation conditions., (Copyright © 2013 Elsevier B.V. All rights reserved.)

This paper shows systematic spectroscopic studies using Fourier-transform infrared absorption (FT-IR), Fourier-transform Raman (FT-Raman), and surface-enhanced Raman (SERS) in an aqueous silver sol of fluoro and formyl analogues of phenylboronic acids: 2-fluorophenylboronic acid (2-F-PhB(OH)2), 3-fluorophenylboronic acid (3-F-PhB(OH)2), 4-fluorophenylboronic acid (4-F-PhB(OH)2), 2-formylphenylboronic acid (2-CHO-PhB(OH)2), 3-formylphenylboronic acid (3-CHO-PhB(OH)2), and 4-formylphenylboronic acid (4-CHO-PhB(OH)2). To produce an extensive table of vibrational spectra, density functional theory (DFT) calculations with the B3LYP method at the 6-311++G(d,p) level of theory were performed for the ground state geometry of the most stable species, dimers in cis-trans conformation. On the basis of the SERS spectral profile, the adsorption modes of the phenylboronic acid isomers were proposed. The type of substituent and its position in the phenyl ring have a strong influence on the geometry of isomers on the silver nanoparticle's surface. This effect was especially evident in the case of 4-CH-PhB(OH)2, for which dearomatization of the phenyl ring took place upon adsorption.

This work presents Fourier transform Raman (FT-Raman), Fourier transform absorption infrared (FT-IR), and surface-enhanced Raman scattering (SERS) spectroscopic investigations of three m-nitrophenyl α-guanidinomethylphonic acids, including m-NO2PhG(cHex)P, m-NO2PhG(Morf)P, and m-NO2PhG(An)P, adsorbed onto colloidal and roughened silver surfaces. The SERS spectra were deconvoluted to determine the overlapped bands from which the specific molecular orientation can be deducted. The vibrational wavenumbers are calculated through density functional theory (DFT) at the B3LYP/6-31++G** level with the Gaussian 03, Raint, GaussSum 0.8, and GAR2PED software packages. The experimental and calculated vibrational bands are compared to those from SERS for the investigated compounds adsorbed on colloidal and roughened silver surfaces. The geometry of these molecules on the SERS-active silver surfaces is deduced from the observed changes in both the intensity and width of the Raman bands in the spectra of the bound species relative to the free species.

Here, we report a systematic surface-enhanced Raman spectroscopy (SERS) study of the structures of five N-benzylamino(boronphenyl)-methylphosphonic acids: N-benzylamino-(3-boronphenyl)-S-methylphosphonic acid (m-PhS), N-benzylamino-(4-boronphenyl)-S-methylphosphonic acid (p-PhS), N-benzylamino-(2-boronphenyl)-R-methylphosphonic acid (o-PhR), N-benzylamino-(3-boronphenyl)-R-methyl-phosphonic acid (m-PhR), and N-benzylamino-(4-boronphenyl)-R-methylphosphonic acid (p-PhR) adsorbed on nanometer-sized colloidal particles (20-25 nm). For example, we showed that all of these molecules interact with the colloidal surface through a boronophenyl ring, which plane remained vertical on the surface. For p-PhS, a preferential interaction between the P=O bond and the colloidal silver surface is observed to be stronger than for the remaining compounds. The -P(OH)(2) and -B(OH)(2) fragments take part in the adsorption process. However, the B-O bond of p-PhS and p-PhR seemed to be tilted with respect to the silver surface., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Adsorption of decapeptide neuromedin B (NMB) on copper electrode has been investigated by in situ surface-enhanced Raman scattering (SERS) spectroelectrochemistry in the temperature interval from 12 to 72 °C at -0.600 and -1.000 V potentials. It was found that intensities of peptide bands decrease at temperatures above 30 °C with higher decrease slope at -1.000 V. Frequency of F12 mode (1004 cm(-1)) of non-surface-interactive phenylalanine residue was found to be insensitive to temperature variation at both studied electrode potentials, while frequency-temperature curves for surface-interactive groups (Amide-III, methylene) were found to be controlled by the potential. In particular, opposite frequency-temperature trends were detected for Amide-III (Am-III) mode indicating decrease in H-bonding interaction strength of amide C[double bond, length as m-dash]O and N-H groups above 38 °C for -0.600 V, and increase in H-bonding interaction strength between 12 and 72 °C for -1.000 V. Anomalous Am-III temperature-dependence of the frequency at -1.000 V was explained by temperature-induced transformation of a disordered secondary structure to a helix-like conformation. The potential-difference spectrum revealed interaction of methylene groups with Cu surface at sufficiently negative potential values because of the appearance of a soft C-H stretching band near 2825 cm(-1) and a broad band near 2904 cm(-1) assigned to vibration of a distal C-H bond of the surface-confined methylene group. Consequently, a rapid decrease in frequency of CH(2)-stretching band with temperature was observed at -1.000 V, while no essential frequency changes were detected for this mode at -0.600 V. The results show that electrode potential controls the temperature-dependence of the frequency for vibrations associated with surface-interactive molecular groups.

Five analogues of a novel group of boron derivatives of aminophosphonic acids-N-benzylamino-(3-boronphenyl)-S-methylphosphonic acid (m-PhS), N-benzylamino-(4-boronphenyl)-S-methylphosphonic acid (p-PhS), N-benzylamino-(2-boronphenyl)-R-methylphosphonic acid (o-PhR), N-benzylamino-(3-boronphenyl)-R-methylphosphonic acid (m-PhR), and N-benzylamino-(4-boronphenyl)-R-methylphosphonic acid (p-PhR)-were studied using Fourier transform infrared (FT IR), Fourier transform Raman (FT RS), and surface-enhanced Raman (SERS) spectroscopies. Analysis of obtained FT IR and FT RS spectra show that all investigated compounds in the solid state exist as dimeric species formed by an H-bonding interaction between -B(OH)(2) moieties of each monomer. In addition, comparison of the wavenumbers, intensities, and broadness of bands from the FT Raman and SERS spectra allowed information to be obtained regarding the adsorption geometry of the investigated compounds immobilized onto an electrochemically roughened silver substrate.

This study reports the Raman (FT-Raman) and absorption infrared (FT-IR) spectra, based on calculated wavenumbers and normal modes of vibrations, of the following compounds: L-Leu-D-NH-CH(Me)-PO(3)H(2) (LI), L-Leu-NH-C(Me)(2)-PO(3)H(2) (LII), L-Leu-D-NH-CH(Et)-PO(3)H(2) (LIII), L-Leu-L-NH-CH(Et)-PO(3)H(2) (LIV), L-Leu-L-NH-CH(EtOH)-PO(3)H(2) (LV), L-Leu-NH-C(Me)(Et)-PO(3)H(2) (LVI), L-Leu-L-NH-CH(PrA)-PO(3)H(2) (LVII), L-Leu-L-NH-CH(c-Pr)-PO(3)H(2) (LVIII), L-Leu-L-NH-CH(t-Bu)-PO(3)H(2) (LIX), L-Leu-L-NH-CH(BuA)-PO(3)H(2) (LX), L-Leu-L-NH-CH(c-Bu)-PO(3)H(2) (LXI), and L-Leu-L-NH-C(Adm)-PO(3)H(2) (LXII). The equilibrium geometries and vibrational wavenumbers were calculated using density functional theory (DFT) at the B3LYP, 6-311++G** level using Gaussian 03, Raint, GaussSum 0.8, and Gar2ped software. We briefly compare and analyze the experimental and calculated vibrational wavenumbers in the range 4000-400 cm(-1). In addition, the Raman wavenumbers are compared to those from the surface-enhanced Raman scattering (SERS) spectra for the phosphono analogues of l-leucine (l-Leu) adsorbed on a colloidal silver surface in an aqueous solution. The geometries of these molecules etched on the silver surface were deduced from observed changes in both the intensity and broadness of Raman bands in the spectra of the bound versus free species. For example, LVI appears to adsorb onto the colloidal silver particles mainly through the amine group and amide bond, which assists in the adsorption process, whereas LII shows strongly enhanced SERS bands due to the rocking, twisting, and stretching vibrations of the N(amid)C(sg)(Me)(2)P fragment, suggesting that this peptide's interaction with the silver surface occurs mainly via this fragment. On the other hand, the most dominant SERS bands of LIII and LIV due to the P═O bond stretches reflect P═O···Ag complex formation.

Surface-enhanced Raman scattering (SERS), electrochemistry, and generalized two-dimensional correlation analysis (G2DCA) methods were used to define neuromedin B (NMB) ordered superstructures on Ag, Au, and Cu electrode surfaces at different applied electrode potentials in an aqueous solution at physiological pH. The orientation of NMB and the adsorption mechanism were determined based on the analysis of enhancement, broadness, and shift in wavenumber of particular bands, which allow drawing some conclusions about NMB geometry and changes in this geometry upon change of the electrode type and applied electrode potential. The presented data demonstrated that NMB deposited onto the Ag, Au, and Cu electrode surfaces showed bands due to vibrations of the moieties that were in contact/close proximity to the electrode surfaces and thus were located on the same side of the polypeptide backbone. These included the Phe(9) and Trp(4) rings, the sulfur atom of Met(10), and the -CCN- and -C═O units of Asn(2). However, some subtle variations in the arrangement of these fragments upon changes in the applied electrode potential were distinguished. The Amide-III vibrations exhibited an electrochemical Stark effect (potential dependent frequencies) with Stark tuning slope sensitive to the electrode material. Potential-difference spectrum revealed that the imidazole ring of His(8) was bonded to the Cu electrode surface at relatively positive potentials.

The color varieties of spodumene (green spodumene, kunzite) from Nilaw mine (Nuristan, Afghanistan) have been investigated by microthermometry and Raman spectroscopy analyses. These minerals are rich in primary and secondary fluid inclusions. Measured values of temperature homogenization (T(h)) and pressure (P) for selected fluid-inclusion assemblages (I-IV) FIA in green spodumene and (I-II) FIA in kunzite ranges from 370 to 430°C, 1.16 to 1.44 kbar and 300 to 334°C, 0.81 to 1.12 kbar, respectively. The brine content and concentration varies from 4.3 to 6.6 wt.% eq. NaCl. Numerous and diverse mineral phases (quartz, feldspars, mica, beryl, zirconium, apatite, calcite, gypsum) present in this mineral as solid inclusions were studied by Raman microspectroscopy. Raman spectra of selected fluid, organic and solid inclusions were collected as line or rectangular maps and also depth profiles to study their size and contents. There appeared very interesting calcite (156, 283, 711 and 1085 cm(-1)), beryl (324, 397, 686, 1068 and 3610 cm(-1)), topaz (231, 285, 707, 780 and 910 cm(-1)) and spodumene (355, 707 and 1073 cm(-1)) inclusions accompanied by fluid and/or organic inclusions (liquid and gas hydrocarbons) with bands at 2350 cm(-1) (CO(2), N(2)), 2550 cm(-1) (H(2)S) and 2900 cm(-1) (C(2)H(6)-CH(3)). Some solid inclusions contain carbonaceous matter (D-band at ca. 1320 cm(-1) and/or G-band at ca. 1600 cm(-1))., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Here, we report a systematic study showing an analogy between the activities of peptide structural component interactions with both a metal substrate and a G-protein-coupled seven-transmembrane receptor. In the present work, N-terminal fragments of human neurotensin (NT), NT(1-6), NT(1-8), and NT(1-11), and C-terminal fragments of human neurotensin, NT(8-13) and NT(9-13), as well as six specifically mutated analogues with the following modifications, Acetyl-NT(8-13), [Dab(9)]NT(8-13), [Lys(8),Lys(9)]NT(8-13), [Lys(8)-(®)-Lys(9)]NT(8-13), [Lys(9),Trp(11),Glu(12)]NT(8-13), and Boc[Lys(9),Leu(13)OMe]NT(9-13), were immobilized onto an electrochemically roughened silver electrode surface in an aqueous solution. The orientation of the adsorbed molecules and the adsorption mechanism were determined from surface-enhanced Raman scattering (SERS) spectra. A comparison was made between the structures of the mutated fragments to determine how changes in the mutation of the structure influenced the adsorption properties. The contribution of the structural components to the peptides' ability to interact with the NTR1 receptor was correlated with the SERS patterns. The SERS spectra revealed that the substitution of native amino acids in the investigated peptides slightly influenced their adsorption state on an electrochemically roughened silver surface. Thus, all of the investigated peptides, excluding [Lys(9),Trp(11),Glu(12)]NT(8-13), tended to adsorb to the surface mainly via the oxygen atom of the deprotonated phenol group, and the phenyl ring became rearranged in a slightly different edge-on manner (NT(1-8), NT(1-11), NT(8-13), Acetyl-NT(8-13), [Dab(9)]NT(8-13), [Lys(8),Lys(9)]NT(8-13), [Lys(8)-(®)-Lys(9)]NT(8-13), NT(9-13), and Boc[Lys(9), Leu(13)OMe]NT(9-13)) or in an almost horizontal manner (N(1-6)) of the tyrosine residue. Meanwhile, [Lys(9),Trp(11),Glu(12)]NT(8-13) bound to this substrate through the tilted phenyl coring of the tryptophan residue. Small changes in the enhancement of the CCNH(2), COO(-), and -CONH- group modes upon adsorption, which were consistent with the adsorption of these peptides, also occurred (with slightly different strengths) through the nitrogen and oxygen lone pair of electrons in these groups. However, for NT(1-8), a greater preferential interaction between the guanidine group of Arg(8) and the roughened silver substrate was observed in comparison to that between the guanidine moiety of the other investigated peptides and the substrate. Vibrational spectroscopy was also used to produce an extensive table of Raman and absorption infrared spectra to allow for a rapid and accurate structural determination of these biomolecules and to allow the reader to easily follow the proposed SERS assignments.

The human, pig, and frog neurotensins and four single-site mutants of human neurotensin (NT), having the following modifications, [Gln(4)]NT, [Trp(11)]NT, [D-Trp(11)]NT, and [D-Tyr(11)]NT, were immobilized onto an electrochemically roughened silver electrode surface in an aqueous solution. The orientation of adsorbed molecules was determined from surface-enhanced Raman scattering (SERS) measurements. A comparison was made between these structures to determine how the change upon the mutation of the neurotensin structure influences its adsorption properties. The SERS patterns were correlated with the contribution of the structural components of the aforementioned peptides to the ability to interact with the NTR1 G-protein receptor. Briefly, the SERS spectra revealed that the substitution of native amino acids in investigated peptides influenced slightly their adsorption state on an electrochemically roughened silver surface. Thus, human, pig, and frog neurotensins and [Gln(4)]NT and [D-Tyr(11)]NT tended to adsorb to the surface via the tyrosine ring, the oxygen atom of the deprotonated phenol group of Tyr(11), and the -CH(2)- unit(s), most probably of Tyr(11), Arg(9), and/or Leu(13). The observed changes in the enhancement of the deprotonated Tyr residue SERS signals indicated a further parallel orientation of a phenol-O bond with regard to the silver surface normal for pig NT, [Gln(4)]NT, and [D-Tyr(11)]NT, whereas the orientation was slightly tilted for human and frog NT. In the case of [Trp(11)]NT and [D-Trp(11)]NT, the formation of a peptide/Ag complex was confirmed by strong SERS bands involving the phenyl co-ring of Trp(11)/d-Trp(11) and -CH(2)- vibrations and the tilted and flat orientations of the two compounds with respect to the surface substrate. The spectral features were accompanied by a SERS signal caused by vibrations of the carboxyl group of C-terminal Leu(13) and the guanidine group of Arg(9). Reported changes in SERS spectra of L and D isomers were fully supported by generalized two-dimensional correlation analysis. Additionally, a combination of mutation-labeling and vibrational spectroscopy (Fourier-transform Raman and absorption infrared) was used to investigate the possible peptide conformations and environments of the tyrosine residues.

In the present work, γ-terpinene (a 1,4-diene derivative) and α-phellandrene (1,3-diene derivative) were isolated in cryogenic argon matrices and their structures, vibrational spectra, and photochemistries were characterized with the aid of FTIR spectroscopy and quantum chemical calculations performed at the DFT/B3LYP/6-311++G(d,p) level of approximation. The molecules bear one conformationally relevant internal rotation axis, corresponding to the rotation of the isopropyl group. The calculations provide evidence of three minima on the potential energy surfaces of the studied molecules, where the isopropyl group assumes the trans, gauche+, and gauche- conformations (T, G+, G-). The signatures of all these conformers were identified in the experimental matrix infrared spectra, with the T forms dominating, in agreement with the theoretical predicted abundances in gas phase at room temperature. In situ UV (λ > 200 nm) irradiation of matrix-isolated α-phellandrene led to its isomerization into an open-ring species. The photoproduct was found to exhibit the ZE configuration of its backbone, which to be formed from the reactant molecule does not require extensive structural rearrangements of both the reagent and matrix. γ-Terpinene was photostable when subjected to irradiation under the same experimental conditions. In addition, the liquid compounds at room temperature were also investigated by FTIR-ATR and FT-Raman spectroscopies.

The vibrational structures of Nociceptin (FQ), its short bioactive fragments, and specifically-modified [Tyr¹]FQ (1-6), [His¹]FQ (1-6), and [His(1,4)]FQ (1-6) fragments were characterized. We showed that in the solid state, all of the aforementioned peptides except FQ adopt mainly turn and disordered secondary structures with a small contribution from an antiparallel β-sheet conformation. FQ (1-11), FQ (7-17) [His¹]FQ (1-6), and [His(1,4)]FQ (1-6) have an α-helical backbone arrangement that could also slightly influence their secondary structure. The adsorption behavior of these peptides on a colloidal silver surface in an aqueous solution (pH = ∼8.3) was investigated by means of surface-enhanced Raman scattering (SERS). All of the peptides, excluding FQ (7-17), chemisorbed on the colloidal silver surfaces through a Phe⁴ residue, which for FQ, FQ (1-11), FQ (1-6), [Tyr¹]FQ (1-6), and [His¹]FQ (1-6) lies almost flat on this surface, while for FQ (1-13) and FQ (1-13)NH₂ adopts a slightly tilted orientation with respect to the surface. The Tyr¹ residue in [Tyr¹]FQ (1-6) does not interact with the colloidal silver surface, suggesting that the Tyr¹ and Phe⁴ side chains are located on the opposite sides of the peptide backbone, which can be also true for His¹ and Phe⁴ in [His¹]FQ (1-6). The lone pair of electrons on the oxygen atom of the ionized carbonyl group of FQ (1-13) and FQ (7-17) appears to be coordinated to the colloidal silver nanoparticles, whereas in the case of the remaining peptides, it only assists in the adsorption process, similar to the --NH⁴ group. We also showed that upon adsorption, the secondary structure of these peptides is altered., (© 2010 Wiley Periodicals, Inc.)

Alpha-terpinene is a natural product that is isolated from a variety of plant sources and is used in the pharmaceutical and perfume industries. In the atmosphere, under the influence of sunlight, alpha-terpinene undergoes a series of photochemical transformations and contributes to the formation of the secondary organic aerosols. In the present work, alpha-terpinene has been isolated in low-temperature xenon and argon matrices, and its structure and photochemistry were characterized with the aid of FTIR spectroscopy and DFT calculations. The theory predicts three conformers resulting from the rotation of the exocyclic CH(CH(3))(2) framework, that is, Trans (T) and Gauche (G+ and G-) forms. The two Gauche conformers were estimated to be higher in energy, by ca. 1.75 kJ mol(-1), than the most stable Trans form. The signatures of all three conformers were found to be present in the experimental low-temperature matrix spectra with the T form dominating in diluted matrices. The conformational ratio was found to shift in favor of the G+/G- forms upon annealing of the matrices as well as in the neat alpha-terpinene liquid. UV-C (lambda > 235 nm) irradiation of matrix-isolated alpha-terpinene led to its isomerization into an open-ring species, which is produced in the Z configuration and in the conformations that require the smallest structural rearrangements of both the reagent and matrix.

Neuromedin C (NMC) is a decapeptide (Gly-Asn-His-Trp-Ala-Val-Gly-His-Leu-Met-NH(2)) that acts as a growth factor in a wide range of tumors including carcinomas of the pancreas, stomach, breast, prostate, and colon. We report surface-enhanced Raman spectra (SERS) of NMC on electrochemically roughened Ag, Au, and Cu electrode surfaces over an electrode potential range varying from +0.200 to -1.200 V (depending on the electrode material). We compared the SERS spectra to the Raman spectrum of the corresponding solid species. The SERS spectra were dominated by L-tryptophan (Trp) vibrations. This indicates that Trp interacted with the metallic surfaces of the electrodes, either by binding directly to the surface or by staying in close proximity to the surface. Characteristic SERS bands showed that, in the case of the Ag electrode, the Trp residue was almost perpendicular to the surface. In contrast, the Trp residue was slightly tilted with respect to the Au electrode surface, and Trp remained some distance from the surface of the Cu electrode. These differences were due to differences in surface rheology and in the type of metal (Ag vs Au vs Cu) responsible for the observed enhancement mechanism. On the other hand, variations in the electrode potentials only had a slight influence on the SERS patterns and the observed changes were mainly due to the reorientation of the Trp ring with respect to the electrode surface. These findings were fully supported by generalized two-dimensional correlation analysis (G2DCA).

In this work, we report systematic surface-enhanced Raman spectroscopy (SERS) and generalized two-dimensional correlation analysis (G2DCA) studies of the structures of five specifically modified phenylalanine-substituted C-terminal bombesin 6-14 fragments (BN(6-14)). The fragments studied have all been tested as chemotherapeutic agents in cancer therapy, and they form amino acid sequences in bombesin: cyclo[d-Phe(6),His(7),Leu(14)]BN(6-14), [D-Phe(6),Leu-NHEt(13),des-Met(14)]BN(6-14), [D-Phe(6),Leu(13)-((R))-p-Cl-Phe(14)]BN(6-14), [D-Phe(6),beta-Ala(11),Phe(13),Nle(14)]BN(6-14), and [D-Tyr(6),beta-Ala(11),Phe(13),Nle(14)]BN(6-14). We adsorbed these fragments onto roughened Ag, Au, and Cu electrode surfaces, using a potential range from -1.200 to 0.400 V, at physiological pH. We compared the adsorption mechanism of each fragment on these substrates, as well any changes observed with varying electrode potential, to determine the relationship between adsorption strength and geometry of each of the peptides wherever it was possible. For example, we showed that none of these fragments directly interact with the Ag, Au, and Cu surfaces via residues of Phe (phenylalanine) and Trp(8) (L-tryptophane at position 8 of the BN amino acid sequence) or by an amide bond, due to a very small shift in wavenumber of their characteristic vibrations. Specific interactions were recognized from the broadening, wavenumber shift, and increase in intensity of the W18 Trp(8) mode near 759 cm(-1) and decrease in nu(12) vibration frequency of the Phe residue. In general, more intense SERS bands were observed due to the Phe ring, compared with the Trp(8) ring, which suggested a preferential adsorption of phenylalanine over tryptophane. For [D-Tyr(6),beta-Ala(11),Phe(13),Nle(14)]BN(6-14), the data also suggest some interaction of a D-Tyr(6) residue (D-tyrosine at position 6). Finally, only slight rearrangements of these moieties on the substrates are observed with changes in electrode potential.

The vibrational and reorientational motions of H(2)O ligands and NO(3)(-) anions were investigated by Fourier transform middle-infrared Raman scattering (RS) spectroscopy and phonon density of states, calculated from incoherent inelastic neutron scattering, in the high- and low-temperature phases of [Ca(H(2)O)(4)](NO(3))(2). The theoretical IR and RS spectra were also calculated by means of the quantum chemistry method using density functional theory with PBE1PBE functional at 6-311++G(2d,2p) basis set level. The temperature dependences of the full width at half maximum values of nu(s)(H(2)O) bands in both the infrared absorption and the RS spectroscopy suggest that the observed phase transitions (at T(C1) and T(C2)) are not connected with a drastic change in the speed of H(2)O reorientational motions. However, similar Raman nu(4)(NO(3)(-)) band shape measurements as a function of temperature revealed the existence of a fast NO(3)(-) reorientation in phase I, which is abruptly slowed at the phase transition at T(C1). Activation energy values for the reorientational motions of H(2)O ligands and NO(3)(-) anions were calculated.

Here, we report a systematic surface-enhanced Raman spectroscopy (SERS) study of the structures of phosphonate derivatives of the N-heterocyclic aromatic compounds imidazole (ImMeP ([hydroxy(1H-imidazol-5-yl)methyl]phosphonic acid) and (ImMe)(2)P (bis[hydroxy-(1H-imidazol-4-yl)-methyl]phosphinic acid)), thiazole (BAThMeP (butylaminothiazol-2-yl-methyl)phosphonic acid) and BzAThMeP (benzylaminothiazol-2-yl-methyl)phosphonic acid)), and pyridine ((PyMe)(2)P (bis[(hydroxypyridin-3-yl-methyl)]phosphinic acid)) adsorbed on nanometer-sized colloidal particles. We compared these structures to those on a roughened silver electrode surface to determine the relationship between the adsorption strength and the geometry. For example, we showed that all of these biomolecules interact with the colloidal surface through aromatic rings. However, for BzAThMeP, a preferential interaction between the benzene ring and the colloidal silver surface is observed more so than that between the thiazole ring and this substrate. The PC(OH)C fragment does not take part in the adsorption process, and the phosphonate moiety of ImMeP and (ImMe)(2)P, being removed from the surface, only assists in this process.

The crystal structure of the Cu(II) complex with Vitamin B(13) (orotic acid), cis-[Cu(oro)(NH(3))(2)] has revealed the presence of unusual, noncovalent pi-type interaction between the chelated Cu(II) ion and the C horizontal lineC bond of the uracilate ring [Michalska et al. Polyhedron 2007, 26, 4303]. In this work, the origin and strength of this interaction is thoroughly investigated. Comprehensive studies of the molecular structures and vibrational spectra of the title complex have been performed by using the unrestricted density functional theory methods, B3LYP, and the newly developed M05-2X functional. Calculations at the UMP2 level were also carried out for comparison. A variety of basis sets have been employed in the DFT calculations, including aug-cc-pVTZ, D95V(d,p), SDD, and LanL2DZ. The (63)Cu/(65)Cu isotope substitution technique was applied to identify the copper-ligand vibrations in the infrared spectra. The clear-cut assignment of all the bands in the FT-IR and Raman spectra of the title complex has been made on the basis of the calculated potential energy distribution, PED. It is shown that an extremely intense band at 1210 cm(-1) in the Raman spectrum of cis-[Cu(oro)(NH(3))(2)] is diagnostic for the N-1 deprotonation of the uracilate ring and coordination to the copper(II) ion. The B3LYP functional performs better than M05-2X in predicting vibrational frequencies of this complex in the solid state. Intermolecular interactions in crystal were modeled by the supramolecular system consisting of cis-[Cu(oro)(NH(3))(2)], ethylene (above), and formaldehyde (below the copper coordination plane). The stable structure of this system has been predicted only by the M05-2X and MP2 methods, which include dispersion energy, whereas the B3LYP calculations failed in geometry optimization. The distance between the Cu atom and the C horizontal lineC bond, predicted by the M05-2X method (3.00 A) is similar to the van der Waals contacts between the stacking bases in DNA. The calculated interaction energy between the chelated Cu(II) complex and ethylene amounts to -7.33 kcal mol(-1), which is similar to that determined for stacked uracil dimer. It is concluded that the London dispersion energy plays a significant role in the noncovalent interaction between the chelated Cu(II) ion and the uracilate ring in the crystal of cis-[Cu(oro)(NH(3))(2)]. Many copper enzymes in their active sites contain the chelated Cu(II) ion and the aromatic groups (Phe, Tyr and Trp) as the potential binding sites; therefore, the noncovalent copper(II)-pi interaction can be very important for the structure and functioning of these enzymes.

Vibrational spectra of adenosine bearing benzo-15-crown ether moiety [N(6)-4'-(benzo-15-crown-5)-adenosine, AC] have been recorded in solid phase (FT-IR, FT-Raman) and in aqueous solution on the silver colloid surface (SERS). To interpret a very complex vibrational pattern of experimental data, geometrical parameters (molecular structure) as well as harmonic frequencies of the isolated molecule were calculated at the density functional theory level [B3LYP/6-31G(d)]. Assignment of the observed vibrational modes is discussed on the basis of the theoretical results obtained for N(6)-4'-(benzo-15-crown-5)-adenosine as well as its molecular isolated fragments, i.e. adenosine and benzo-15-crown ether. Our analysis of SERS spectrum indicates that adenine and benzo-15-crown ether take tilted orientation while the imino group and ribose adopt almost vertical position in respect to the metal surface. Moreover, calculated atomic charge distribution gives interesting insights into changes of electron density allocation in investigated fragments.

Hemoglobin (Hb) is an allosteric tetrameric protein made up of alphabeta heterodimers. The alpha and beta chains are similar, but are chemically and structurally distinct. To investigate dynamical differences between the chains, we have prepared tetramers in which the chains are isotopically distinguishable, via reconstitution with (15)N-heme. Ligand recombination and heme structural evolution, following HbCO dissociation, was monitored with chain selectivity by resonance Raman (RR) spectroscopy. For alpha but not for beta chains, the frequency of the nu(4) porphyrin breathing mode increased on the microsecond time scale. This increase is a manifestation of proximal tension in the Hb T-state, and its time course is parallel to the formation of T contacts, as determined previously by UVRR spectroscopy. Despite the localization of proximal constraint in the alpha chains, geminate recombination was found to be equally probable in the two chains, with yields of 39 +/- 2%. We discuss the possibility that this equivalence is coincidental, in the sense that it arises from the evolutionary pressure for cooperativity, or that it reflects mechanical coupling across the alphabeta interface, evidence for which has emerged from UVRR studies of site mutants.

We used surface-enhanced Raman scattering (SERS) to characterize the adsorption behavior of bombesin (BN) and five BN-related peptides, including phyllolitorin, [Leu(8)]phyllolitorin, neuromedin C (NMC), neuromedin B (NMB), and PG-L (Pseudophryne guntheri), in a silver colloidal solution. Our experiments show that the pyrrole coring of the Trp and aromatic ring of Phe of these peptides are preferentially adsorbed on silver nanoparticles. However, the geometry of the rings and the strength of the interactions with this surface vary among peptides. Additionally, these peptides are weakly coordinated to the colloidal silver surface through the CO fragment of a peptide bond, between Gln/Leu/His and Trp residues, and CNC and SC fragments. Also, using the recently reported SERS spectra of these peptides immobilized onto an electrochemically roughened silver electrode surface, we demonstrate substrate-induced changes in the adsorption behavior of these peptides. Comparative analysis indicates that the interactions between peptides and the enhancing surfaces depend strongly on the geometry of the Trp, CONH, and SC fragments of these biomolecules etched on the surfaces.

FT-IR and FT-RS spectra of three phosphonate tripeptides containing P-terminal L-Met-L-Ala [L-Gly-L-Met-L-Ala-PO3H2 (GMA), L-Leu-L-Met-L-Ala-PO3H2 ( LMA), and L-Phe-L-Met-L-Ala-PO3H2 (PMA)] were recorded and analyzed. Vibrational wavenumbers and intensities were calculated by density functional theory (DFT) at the B3LYP/6-311++G** level of theory and compared to these molecules in solid form. On the basis of this comparison, conclusions were drawn about the molecular structures. At the same time, the experimental data served as a test for the computational results. SERS spectra were recorded in a silver colloidal dispersion. Silver colloidal dispersions prepared by simple borohydride reduction of silver nitrate were used as substrates. A comparison is made between the SERS spectra and the spectra of the solid sample. Also, the capability of SERS for spectral fingerprinting of analytes with close structural properties using easily prepared substrates and relatively simple instrumentation is illustrated. By careful analysis, we obtained information on the orientation of these tripeptides and specific-competitive interactions of their functional groups with the silver surface. For example, all molecules are thought to adsorb on a silver surface via a P=O bond and a sulfur atom. In addition, the amide bond of GMA assists in the adsorption process, adopting a tilted orientation on the surface, with the N-H unit being closer to the surface than the C=O moiety. Conversely, the C=O unit of the LMA-CONH- bond lies closer to the silver surface than the N-H moiety. The -CH 3 group and P-O bond of LMA additionally interact with the silver surface, whereas for PMA the L-Phe lies almost flat on the colloidal silver surface.

Raman (RS) and surface-enhanced Raman scattering spectra (SERS) were measured for various length carboxyl terminal fragments (X-14 of amino acid sequence) of bombesin ( BN): BN13-14, BN12-14, BN11-14, BN10-14, BN9-14, and BN8-14 in silver colloidal solutions. Density functional theory (DFT) calculations of Raman wavenumbers and intensities with extended basis sets (B3LYP/6-31++G**) were performed with the aim of providing the definitive band allocations to the normal coordinates. The proposed band assignment is consistent with the assignment for similar compounds reported in the literature. The nonadsorbed and adsorbed molecular structures were deducted by detailed spectral analysis of the RS and SERS spectra, respectively. This analysis also allowed us to propose the particular surface geometry and orientation of these peptides on silver surface, and their specific interaction with the surface. For example, a SERS spectrum of BN8-14 indicates that the interaction of a thioether atom and Trp8 with the silver surface is favorable and may dictate the orientation and conformation of adsorbed peptide. One of the most prominent and common features in all of the fragments' SERS spectra is a approximately 692 cm (-1) band due to nu(C-S) accompanied by two or three bands of different C-S conformers for all, except BN8-14, which suggests that all of the above-mentioned compounds adsorb on the silver surface through the thioether atom and that the attachment of Trp8 produces limitation in a number of possible C-S conformers adopted on this surface. Our results also show clearly that His12 and CO do not interact with the colloid surface, which supports our earlier results.

An extensive analysis of the conformational space of tryptophan (Trp) was performed at the B3LYP/6-311++G(d,p) level and verified by comparison with the infrared spectra of the compound isolated in low-temperature argon and xenon matrixes. Different types of conformers have been unequivocally identified in the matrixes. Type I exhibits the trans arrangement of the carboxylic group and is stabilized by an O-H...N intramolecular H-bond. Types II and III have the carboxylic group in the cis conformation and feature N-H...O=C and N-H...O-C hydrogen bonds, respectively. Three individual conformers of type I were identified in the matrixes. Other conformational degrees of freedom are related with the Calpha-Cbeta-Cgamma=C and C1-Calpha-Cbeta-Cgamma angles (chi1 and chi2, respectively). In proteins, these two dihedral angles define the conformations of the amino acid residues. In monomeric Trp, chi1 adopts the "+" (ca. +90 degrees ) and "-" (ca. -90 degrees ) orientations, while average values of -67.4, 170.5, and 67.6 degrees ("a", "b", and "c", respectively) were found for chi2. Theoretical analysis revealed two important factors in stabilizing the structures of the Trp conformers: the H-bond type and electrostatic interactions. Classified by the H-bond type, the most stable are forms I, followed by II and III. Out of possible combinations of the chi1 and chi2 dihedral angles, "a+", "b+", and "c-" were theoretically found more stable than their "a-", "b-", and "c+" counterparts. Thus, the stabilizing effect of interactions involving the pyrrole ring (which are possible in Ia+, Ib+, and Ic- conformers) is considerably higher compared to those in which the phenyl ring is engaged (existing in the Ia-, Ib-, and Ic+ forms).

In an attempt to gain further insight into the nature of the low frequency vibrational modes of hemoglobin and its isolated subunits, a comprehensive study of several different isotopically labeled analogues has been undertaken and is reported herein. Specifically, the resonance Raman spectra, between 200 and 500 cm(-1), are reported for the deoxy and ligated (CO and O2) forms of the isolated alpha and beta subunits containing the natural abundance or various deuterated analogues of protoheme. The deuterated protoheme analogues studied include the 1,3,5,8-C2H3-protoheme (d12- protoheme), the 1,3-C2H3-protoheme (1,3-d6-protoheme), the 5,8-C2H3-protoheme (5,8-d6-protoheme), and the meso-C2H4-protoheme (d4-protoheme). The entire set of acquired spectra has been analyzed using a deconvolution procedure to help correlate the shifted modes with their counterparts in the spectra of the native forms. Interestingly, modes previously associated with so-called vinyl bending modes or propionate deformation modes are shown to be quite sensitive to deuteration of the peripheral methyl groups of the macrocycle, shifting by up to 12-15 cm(-1), revealing their complex nature. Of special interest is the fact that shifts observed for the 1,3-d6- and 5,8-d6-protoheme analogues confirm the fact that certain modes are associated with a given portion of the macrocycle; i.e., only certain modes shift upon deuteration of the 1 and 3 methyl groups, while others shift upon deuteration of the 5 and 8 methyl groups. Compared with the spectra previously reported for the corresponding myoglobin derivatives, the data reported here reveal the appearance of several additional features that imply splitting of modes associated with the propionate groups or that are indicative of greater distortion of the heme prosthetic groups., ((c) 2006 Wiley Periodicals, Inc.)

In this work, Raman spectroscopy (RS) was employed to characterize molecular structures of [Arg8]vasopressin (AVP) and its [Acc2,D-Arg8]AVP, [Acc3]AVP, and [Cpa1, Acc3]AVP analogues. The RS band assignments have been proposed. To determine the mechanism of adsorption of the above-mentioned compounds adsorbed on a colloidal silver surface, surface-enhanced Raman spectra (SERS) were measured. The SERS spectra were used to determine relative proximity of the adsorbed functional groups of [corrected] investigated peptides and their orientation on the silver surface. The AVP and [Acc3]AVP SERS spectra (Acc: 1-aminocyclohexane-1-carboxylic acid) show that the L-tyrosine (Tyr) lies far from the metal surface, whereas the [Cpa1,Acc3]AVP spectrum (Cpa: 1-mercaptocyclohexaneacetic acid) provides evidence that Tyr interacts with the silver surface. These results suggest that [corrected] the binding of the Tyr-ionized phenolic group might be responsible for the selectivity of the analogues. We show that the aromatic ring of L-phenylalanine (Phe) of AVP and [Acc2,D-Arg8]AVP interacts with the silver surface. The strength of this interaction is considerably weaker for [Acc2,D-Arg8]AVP than for AVP. This might be due either to a longer distance between the Phe ring and the silver surface, or to the almost perpendicular orientation of the Phe ring towards the surface. The carbonyl group of the L-glutamine [corrected] (Gln) or L-asparagine [corrected](Asn) of AVP, [Acc2,D-Arg8]AVP, and [Acc3]AVP is strongly bound to the silver surface. We have also found that all peptides adsorb on the silver surface via sulfur atoms of the disulfide bridge, adopting a "GGG" conformation, except [Cpa1,Acc3]AVP, which accepts a "TGG" geometry., (Copyright 2006 Wiley Periodicals, Inc.)

The conformational behavior and infrared spectrum of l-phenylalanine were studied by matrix-isolation infrared spectroscopy and DFT [B3LYP/6-311++G(d,p)] calculations. The fourteen most stable structures were predicted to differ in energy by less than 10 kJ mol(-1), eight of them with abundances higher than 5% at the temperature of evaporation of the compound (423 K). Experimental results suggest that six conformers contribute to the spectrum of the isolated compound, whereas two conformers (IIb(3) and IIIb(3)) relax in matrix to a more stable form (IIb(2)) due to low energy barriers for conformational isomerization (conformational cooling). The two lowest-energy conformers (Ib(1), Ia) differ only in the arrangement of the amino acid group relative to the phenyl ring; they exhibit a relatively strong stabilizing intramolecular hydrogen bond of the O-H...N type and the carboxylic group in the trans configuration (O=C-O-H dihedral angle ca. 180 degrees ). Type II conformers have a weaker H-bond of the N-H...O=C type, but they bear the more favorable cis arrangement of the carboxylic group. Being considerably more flexible, type II conformers are stabilized by entropy and the relative abundances of two conformers of this type (IIb(2) and IIc(1)) are shown to significantly increase with temperature due to entropic stabilization. At 423 K, these conformers are found to be the first and third most abundant species present in the conformational equilibrium, with relative populations of ca. 15% each, whereas their populations could be expected to be only ca. 5% if entropy effects were not taken into consideration. Indeed, phenylalanine can be considered a notable example of a molecule where entropy plays an essential role in determining the relative abundance of the possible low-energy conformational states and then, the thermodynamics of the compound, even at moderate temperatures. Upon UV irradiation (lambda > 235 nm) of the matrix-isolated compound, unimolecular photodecomposition of phenylalanine is observed with production of CO(2) and phenethylamine.

The 1H and 13C NMR spectra of 2-(hydroxyimino)propanohydroxamic acid (hpha) were measured in DMSO-d6 solution. The set of several monomeric structures along with the cluster of H-bonded hpha with three DMSO molecules were proposed to fit the experimental data. The calculated chemical shifts [B3LYP/6-311++G(d,p)] strongly suggested the formation of the cluster in which all the labile protons were H-bonded to the solvent molecules. The comparison between experimental and calculated Raman spectra of hpha in DMSO also suggested that in these conditions the investigated compound forms the proposed cluster rather than dimers. According to our calculations [B3LYP/6-31+G(d)] this cluster was energetically stabilized (84-106 kJ mol-1) compared to postulated dimeric structures. On the other hand, formation of dimers was proposed to be present for hpha in solid state. The comparison of the vibrational data (IR, RS) with the computed harmonic frequencies of three most probable dimers [B3LYP/6-31+G(d)] suggested that the dimer in which molecules adopted the zEe-keto form and were linked by two symmetric, almost linear H-bonds between the carbonyl oxygen atoms and the hydroxamic O-H protons was the predominant species of hpha in the solid state. Thus, the structures of hpha in solid state and DMSO solution appeared to be different.

Surface-enhanced Raman scattering (SERS) spectra were measured for monolayers of various amino acids: L-methionine (Met), L-cysteine (Cys), L-glycine (Gly), L-leucine (Leu), L-phenylalanine (Phe), and L-proline (Pro) and their homodipeptides (Met-Met, Cys-Cys, Gly-Gly, Leu-Leu, Phe-Phe, and Pro-Pro) deposited onto a colloidal gold surface. Orientation of amino acids and their homodipeptides, as well as specific-competitive interactions of their functional groups with the gold surface, were predicted by detailed spectral analysis of the obtained SERS spectra. The analysis performed allowed us to propose a particular surface geometry for each amino acid and homodipeptide on the gold surface. In addition, we compared the structures of these molecules adsorbed on colloidal gold and silver surfaces.

The IR absorption spectrum of salicylhydroxamic acid (sha) isolated in an argon matrix at 12-21 K has been recorded. Calculations of all the possible entgegen and zusammen keto conformers of sha have been performed at the B3LYP/6-311++G(d,p) level of theory. The computed energies, optimized structures, and relative abundances show that sha exists in the matrix as the z,z,z,z-conformer [relative to the C-O(-H), C-C(-N), C-N and N-O bonds, respectively] and is stabilized by two intramolecular H-bonds. Photofragmentation of the compound in matrix and methanol-water solution has been obtained by irradiation with visible and ultraviolet light. o-Hydroxyphenylisocyanate is the main photolysis product in an argon matrix, while salicylamide is the primary photolysis product in methanol-water solution.

Resonance Raman spectra are reported for a series of systematically deuterated analogues of myoglobin in its deoxy state as well as for its CO and O(2) adducts. Specifically, the myoglobin samples studied are those that have been reconstituted with deuterated protoheme analogues. These include the methine deuterated, protoheme-d4; analogue bearing C(2)H(3) groups at the 1, 3, 5, and 8 positions, protoheme-d12; the species bearing C(2)H(3) groups at the 1 and 3 positions only, 1,3-protoheme-d6; and the species bearing C(2)H(3) groups at the 5 and 8 positions only, 5,8-protoheme-d6. While the results are generally consistent with previously reported data for synthetic metalloporphyrin models and previous studies of labeled heme proteins, the high-quality low-frequency RR data reported here reveal several important aspects of these low-frequency modes. Of special interest is the fact that, using the two d6-protoheme analogues, it is shown that certain modes are apparently localized on particular pyrrole rings, while others are localized on different rings; i.e., several of these low-frequency modes are localized on one side of the heme.

We present a Raman and surface-enhanced Raman scattering (SERS) study of the following proteins containing S-S group(s): alpha chymotrypsin (alpha-CHT), insulin, lysozyme, oxytocin (OXT), Streptomyces subtilisin inhibitor (SSI), and trypsin inhibitor (STI). The SERS study is performed in order to understand the adsorption mechanism of the above-mentioned proteins on a colloidal silver surface. The SERS spectra presented here show bands associated mainly with aromatic amino acid vibrations. In addition, two distinct vibrations of the -C-S-S-C- fragment are observed in the Raman and SERS spectra, i.e., nu(SS) and nu(CS). The enhancement of the nu(SS) vibration in the SERS spectra yields evidence that the intact disulfide bridge(s) is (are) located near the silver surface. This finding is supported by the presence of the nu(CS) mode(s). The presence of nus(COO-) and nu(C-COO-) in the SERS spectra in the 1384-1399 cm(-1) and 909-939 cm(-1) regions, respectively, indicate that the negatively charged COO- groups (aspartic and glutamic acids) assist in the binding on the positively charged silver surface. The Raman amide I and III bands observed in the 1621-1633 and 1261-1289 cm(-1) ranges, respectively, indicate that the alpha-helical conformation is favored for binding to the surface over the random coil or beta-sheet conformations. In addition, the presence of the imino group of Trp and/or His indicates that these amino acid residues may also bind to the silver sol.

In this work, we corrected the resonance Raman (RR) results presented earlier for deoxy mesoheme IX-reconstituted hemoglobin (mesoHb) alpha and beta subunits implied that mesohemes in these subunits undergo substantial structural changes upon formation of a hemoglobin tetramer (Biochemistry 29 (1990) 5087). We show that these data were probably due to the improper handling of the deoxy mesoheme subunit preparation. Additionally, we discuss the RR spectra of deoxy, oxy, and CO species of mesoheme IX-reconstituted myoglobin (mesoMb) and alpha and beta deoxy meso hemoglobin subunits, including their analogues with deuterium-substituted mesoheme IX in all methyl groups (d(12)). Based on the obtained data, we propose a complete RR band assignment for all of the investigated molecules. The most pronounced changes are observed for the gamma(7) mode (out-of-plane movement of methane carbon atoms) associated with the interaction of the ethyl groups with the globin. We also show that in mesoheme IX-reconstituted proteins, the O(2) molecule binds stronger than in the case of native species. This is manifested by the up-shift of nu(Fe-O(2)).

Surface-enhanced Raman scattering spectra (SERS) were measured for various amino acids: L-methionine (Met), L-cysteine (Cys), Lglycine (Gly), L-leucine (Leu), L-phenylalanine (Phe), and L-proline (Pro) and their homodipeptides (Met-Met, Cys-Cys, Gly-Gly, LeuLeu, Phe-Phe, and Pro-Pro) in silver colloidal solutions. The geometry and orientation of the amino acids or dipeptides on the silver surface, and their specific interaction with the surface, were deducted by detailed spectral analysis of the SERS spectra. This analysis has allowed us to propose the particular surface geometry of amino acids or dipeptides and also implied that C-C bonds were almost parallel to the surface, as evidenced by the absence of marker bands in the skeletal C-C stretching region of the spectra. Additionally, using "time-dependent" SERS measurements we solved an existing controversy regarding the binding specificity of Gly-Gly on the silver surface.

Surface-enhanced Raman scattering (SERS) spectra of methionine (Met) containing dipeptides: Met-X and X-Met, where X is: L-glycine (Gly), L-leucine (Leu), L-proline (Pro), and L-phenylalanine (Phe) are reported. Using pre-aggregated Ag colloid we obtained high-quality SERS spectra of these compounds spontaneously adsorbed on colloidal silver. Additionally, we measured Raman spectra (RS) of these heterodipeptides in a solid state as well as in acidic and basic solutions. The RS and SERS spectra of Met-X and X-Met presented in this work appear to be different. One of the most prominent and common features in the SERS spectra of all these dipeptides is a band in the 660-690 cm(-1) range that is due to the C-S stretching, v(CS), vibration of Met. This suggests that all the abovementioned compounds adsorb on the silver surface through a thioether atom. On the other hand, the SERS spectra of X-Met show clearly that not only the S atom but also the carboxylate group interact with the colloid surface as manifested by the enhancement of bands in the 920-930 and 1380-1396 cm(-1) regions. These bands are ascribed to the v(C-COO(-)) and v(sym)(COO(-)) vibrations, respectively. Additionally, a SERS spectrum of Phe-Met indicates that the interaction of the thioether atom, amine group, and aromatic side chain with the silver surface is favorable and may dictate the orientation and conformation of adsorbed peptide.

1H and 13C NMR spectra of the oxocarboxylic acid oximes 2-hydroxyiminopropanoic acid (1), 2-(4-methylthiazol-2-yl)-2-(hydroxyimino)acetic acid (2) and 2-cyano-2-(hydroxyimino)acetic acid (3) were measured in DMSO-d6, D2O and acetone-d6 solutions. The data indicate the presence of hydrogen bonding in 1 and 2 and a strong electron-withdrawing effect due to the cyano group in 3. The effect of intra- and intermolecular hydrogen bonding on the hydrogen and carbon chemical shifts in these molecules was studied theoretically. Total energy calculations of the stability of various hydrogen-bonded species, in addition to equilibrium parameters and chemical shifts, were calculated using ab initio methods (RHF, MP2) and density functional theory (B3LYP), implemented in the Gaussian 98 software package. The gauge-including atomic orbital (GIAO) method was used to predict magnetic shielding constants. Chemical shift calculations for the most stable species agree fairly well with the observed data, especially for the hydroxyl protons. Substituents adjacent to the alpha-carbon show some influence of the oximic and carboxyl groups on the 13C chemical shifts, as expected for groups with different polar and anisotropic character., (Copyright 2003 John Wiley & Sons, Ltd.)

Potentiometric studies have shown that Ni(II) forms three pH-dependent complexes with famotidine (L), namely: [NiHL](3+), [NiL](2+) and [NiH(-2)L]. Two of them have been isolated from solution with a Ni/famotidine ratio of 1:1. At pH 6.0, a paramagnetic complex [NiL](2+) with octahedral geometry is formed in which, most likely thiazole N(9) and guanidine N(3) nitrogens are involved in the metal binding. Additionally, two water molecules and two perchlorate anions, ClO(4)(-), fulfil the coordination sphere. The second complex, [NiH(-2)L], that precipitates at pH 8 is diamagnetic and takes square-planar geometry in which four nitrogen donors: N(3), N(9), N(16) and N(20) coordinate to Ni(II). Potentiometric studies, mass spectrometry, FT-IR and Raman spectroscopy are employed to determine and discuss the structure of both complexes. Additionally, 1H, 13C and 15N NMR spectroscopy is used to confirm the binding site in a square-planar complex. The assignment of vibrational bands are made using ab initio HF/CEP-31G method.

Low frequency resonance Raman (RR) spectra are reported for deoxy hemoglobin (Hb), its isolated subunits, its analogue bearing methine-deuterated hemes in all four subunits (Hb-d(4)), and the hybrids bearing the deuterated heme in only one type of subunit, which are [alpha(d4)beta(h4)](2) and [alpha(h4)beta(d4)](2). Analyzed collectively, the spectra reveal subunit-specific modes that conclusively document subtle differences in structure for the heme prosthetic groups in the two types of subunits within the intact tetramer. Not surprisingly, the most significant spectral differences are observed in the gamma(7) mode that has a major contribution from out of plane bending of the methine carbons, a distortion that is believed to relieve strain in the high-spin heme prosthetic groups. The results provide convincing evidence for the utility of selectively labeled hemoglobin hybrids in unraveling the separate subunit contributions to the RR spectra of Hb and its various derivatives and for thereby detecting slight structural differences in the subunits.

Resonance Raman spectra are reported for both the heme domain and holoenzyme of cytochrome P450BM3 in the resting state and for the ferric NO, ferrous CO, and ferrous NO adducts in the absence and presence of the substrate, palmitate. Comparison of the spectrum of the palmitate-bound form of the heme domain with that of the holoenzyme indicates that the presence of the flavin reductase domain alters the structure of the heme domain in such a way that water accessibility to the distal pocket is greater for the holoenzyme, a result that is consistent with analogous studies of cytochrome P450cam. The data for the exogenous ligand adducts are compared to those previously reported for corresponding derivatives of cytochrome P450cam and document significant and important differences for the two proteins. Specifically, while the binding of substrate induces relatively dramatic changes in the nu(Fe-XY) modes of the ferrous CO, ferric NO, and ferrous NO derivatives of cytochrome P450cam, no significant changes are observed for the corresponding derivatives of cytochrome P450BM3 upon binding of palmitate. In fact, the spectral data for substrate-free cytochrome P450BM3 provide evidence for distortion of the Fe-XY fragment, even in the absence of substrate. This apparent distortion, which is nonexistent in the case of substrate-free cytochrome P450cam, is most reasonably attributed to interaction of the Fe-XY fragment with the F87 phenylalanine side chain. This residue is known to lie very close to the heme iron in the substrate-free derivative of cytochrome P450BM3 and has been suggested to prevent hydroxylation of the terminal, omega, position of long-chain fatty acids.

The low frequency resonance Raman spectra of the dioxygen adducts of myoglobin, hemoglobin, its isolated subunits, mesoheme-substituted hemoglobin, and several deuteriated heme derivatives are reported. The observed oxygen isotopic shifts are used to assign the iron-oxygen stretching (approximately 570 cm-1) and the heretofore unobserved delta (Fe-O-O) bending (approximately 420 cm-1) modes. Although the delta (Fe-O-O) is not enhanced in the case of oxymyoglobin, it is observed for all the hemoglobin derivatives, its exact frequency being relatively invariable among the derivatives. The lack of sensitivity to H2O/D2O buffer exchange is consistent with our previous interpretation of H2O/D2O-induced shifts of v(O-O) in the resonance Raman spectra of dioxygen adducts of cobalt-substituted heme proteins; namely, that those shifts are associated with alterations in vibrational coupling of v(O-O) with internal modes of proximal histidyl imidazole rather than to steric or electronic effects of H/D exchange at the active site. No evidence is obtained for enhancement of the v(Fe-N) stretching frequency of the linkage between the heme iron and the imidazole group of the proximal histidine.

The activity of acid phosphatase (E.C.3.1.3.2.), arylsulfatase (E.C.3.1.1.23.), beta-galactosidase (E.C.3.1.1.23.), and beta-acetylglucosaminidase (E.C.3.2.1.30.) in rat liver homogenates of 4.5 month-old male rats is presented in this paper. The degradation processes are observed in rat liver homogenate after incubation. The activity of acid phosphatase and beta-acetylglucosaminidase increases, the activity in one of beta-galactosidase is constant, and arylsulfatase decreases during the time of incubation. Furthermore, the maxima of the enzyme activities shift during the incubation in the time of a day. Gel filtration of acid phosphatase on the Sephadex G-150 Superfine and DEAE-cellulose columns determinate the mutual content of acid phosphatase subunits to isoenzymes I and II in various points of a day. The greatest content of acid phosphatase subunits versus both the isoenzymes content is at 02(24), and the greatest content of isoenzyme II versus the content of isoenzymes I appears at 07(12). From these data it is clear that the period of the isoenzyme II synthesis from the subunit amounts to 5 h, while 10 h are necessary to create the isoenzyme I originated from isoenzyme II. The comparison of acid phosphatase activity before and after the homogenate filtration on the Sephadex column indicates the increase of this enzyme activity after its separation from the other proteins and other components.