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The hydrogen bond between the NH amide group of glycine141 and substrate carbonyl are essential for polarization of the enone fragments and activity of enoyl-CoA hydratase as shown by analysis of the hexadienoyl-CoA-mutant enzyme complex. Substitution of glycine141 with proline reduces the activity and eliminates substrate analogue polarization.

Research has been conducted on the dimethyl sulfoxide reductase from Rhodobacter capsulatus. The structure of the molybdenum cofactor in this reductase has been investigated via Raman spectroscopy.

Results point out that there is a selective polarization of 2,4-Hexadienoyl-coenzyme A active site upon binding to oxidized and reduced medium-chain acyl-CoA dehydrogenase from pig kidney. Data indicate that midpoint potential of the above complex is dependent on pH with a pKa around 9.2.

Research has been conducted on the green fluorescent protein chromophore. The examination of the Raman spectra that has been obtained using 752 nm excitation is discussed.

The vibrational Raman optical activity (ROA) spectra of three single-stranded and two double-stranded polyribonucleotides that follow the A-type conformation was examined. The three distinct regions of the ROA spectra consist of information on various stereochemical elements of nucleic acid structure. This analysis reveals that the central sources of the chirality of the polyribonucleotides contribute greatly to the creation of ROA signals in the independent well-defined spectral regions.

Glycosidic link influences the vibrational Raman optical spectra (ROA) disaccharides and ROA is used for the stereochemical analysis of disaccharides. ROA is suited for oligo- and polysaccharide analysis, which cannot be analyzed by existing physical methods due to flexible glycosidic links. ROA spectra has four regions, each giving complementary information. With this technique, 'map' for carbohydrates with D-glucose residues are assigned.

The structural changes in the nicotinamide ring of NADH when it binds to InhA- enoyl reductase during the catalytic reduction of trans-2-enoyl-ACPs in Mycobacterium tuberculosis are studied using Raman spectroscopy. The mutation of F149- an active site residue in the close proximity of NADP shows that the catalytic activity of the enzyme is dependent on the structure of the cofactor.

Raman and UV-visible absorption spectroscopy is used to investigate the binding of the inhibitor 8 nitroxanthine to urate oxidase. The results suggest that binding to the urate oxidase active site does induce procatalytic changes in the electronic structure of the ligand.

The interaction of hexadienoyl-CoA (HD-CoA), a product analogue, with recombinant pig medium-chain acyl-CoA dehydrogenase (pMCAD) is studied using (super 13)C NMR and (super 1)H-(super 13)C HSQC spectroscopy. Upon binding to oxidized pMCAD, the chemical shifts of the C1, C2 and C3 and C3 HD carbons are shifted upfield by 12.8, 2.1, and 13.8 ppm, respectively.

A study was conducted, using wavelength and time-resolved pump-probe and pump-dump-probe spectroscopy, to investigate the excited and ground-state photoinduced dynamics of the green fluorescent protein (GFP) chromophore and 4'-hydroxybenzylidene-2,3-dimethylimidazolinone (HBDI). The result identifies two pathways such as a 1-photon excited-state twisting, and a 2-photon ionized process.

The role of the oxyanion hole in Mechanistic studies on the medium-chain enzyme (MCAD) catalysis is been elaborated using a combination of kinetic, Raman spectroscopy, and redox combination of measurements. Numerous studies and their respective results concerned with the same are mentioned.

Steady state absorption, fluorescence, and raman spectroscopies are used to investigate the response of wild-type green fluorescent protein (GFP) to UV and visible light. It is reported that the rate of light-driven decarboxylation reaction strongly depends on the excitation wavelength, decreasing in the order 254 nm > 280 nm > 476 nm.

Research has been conducted on antibacterial additive triclosan. Results demonstrate that triclosan is a binding inhibitor of Escherichia coli FabI, and that it binds to E.NAD (super)+ form of the wild-type mutant.

The first definitive assignments of the vibrational spectra of a model green fluorescent protein (GFP) chromophore is presented by using isotope labeling, which is useful for establishing the nature of the changes in the vibrational spectrum because of the protein environment. The observation reveals that these changes can be related to the structure of the chromophore within the protein and linked to the absorption and emission spectra observed for GFPs.

H-bonding in alcohols was examined in the context of the C alpha-H bond strength.

The role of the oxyanion hole in the reaction catalyzed by pig medium-chain acyl-CoA dehydrogenase (pMCAD) has been investigated using enzyme reconstituted with 2'-deoxy-FAD. The k[sub cat] (18.8 ± 0.5 s[sup -1]) and K[sub m] (2.5 ± 0.4 µM) values for the oxidation of n-octanoyl-CoA (C[sub 8]-CoA) by WT pMCAD recombinantly expressed in Escherichia coli are similar to those of native pMCAD isolated from pig kidney. In agreement with previous studies [Engst et al. (1999) Biochemistry 38, 257-267], reconstitution of the WT enzyme with 2'-deoxy-FAD causes a large (400-fold) decrease in k[sub cat] but has little effect on K[sub m]. To investigate the molecular basis for the alterations in activity resulting from changes in hydrogen bonding between the substrate and the enzyme's oxyanion hole, the structure of the product analogue hexadienoyl-CoA (HD-CoA) bound to the 2'-deoxy-FAD-reconstituted enzyme has been probed by Raman spectroscopy. Importantly, while WT pMCAD causes a 27 cm[sup -1] decrease in the vibrational frequency of the HD enone band, from 1595 to 1568 cm[sup -1], the enone band is only shifted 10 cm[sup -1] upon binding HD-CoA to 2'-deoxy-FAD pMCAD. Thus, removal of the 2'-ribityl hydroxyl group results in a substantial reduction in the ability of the enzyme to polarize the ground state of the ES complex. On the basis of an analysis of a similar system, it is estimated that ground state destabilization is reduced by up to 17 kJ mol[sup -1], while the activation energy for the reaction is raised 15 kJ mol[sup -1]. In addition, removal of the 2'-ribityl hydroxyl reduces the redox potential shift that is induced by HD-CoA binding from 18 to 11 kJ mol[sup -1]. Consequently, while ligand polarization caused by hydrogen bonding in the oxyanion hole is intimately linked to substrate turnover, additional factors must be responsible for ligand-induced changes in redox potential. Finally, while replacement of the catalytic base E376 with Gln abolishes the ability of the enzyme to catalyze substrate oxidation and to catalyze the exchange of the C[sub 8]-CoA α-protons with solvent deuterium, the 2'-deoxy-FAD-reconstituted enzyme catalyzes α-proton exchange at a rate (k[sub exc]) of 0.085 s[sup -1], which is only 4-fold slower than k[sub exc] for WT pMCAD (0.35 s[sup -1]). Thus, either the oxyanion hole plays only a minor role in stabilizing the transition state for α-proton exchange, in contrast to its role in substrate oxidation, or the value of k[sub exc] for WT pMCAD reflects a process such as exchange of the E376 COOH proton with solvent. [ABSTRACT FROM AUTHOR]