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The effects of isotopic substitution of tryptophan and solvent on the kinetics of indole elimination reactions of Trpase, were examined.

Research was conducted to investigate the impact of the mutation of Ser39 to threonine on the enantiospecificity and regiospecificity of secondary alcohol dehydrogenases (SADH) from Thermoanaerobacter ethanolicus. This is the first experiment demonstrating a single mutation that results in significant effects on the enantiospecificity of an enzyme. Results indicate that (S)-2 butanol specificity decreased while (R)-2-pentanol specificity was enhanced due to mutation.

The synthesis of S-aryl-L-cysteine S,S-dioxides, a new class of the potent inhibitor of kynureninase, is examined using the comparative molecular field analysis method. Results show that the binding affinities of this kynureninase inhibitor are increased by the presence of any sulfone or ortho amino groups of compounds. These findings confirm the intermediacy of a gem-diol or gem-diolate anion in kynureninase reaction mechanisms.

The pressure-jump and temperature-jump techniques were used to determine the kinetics of relaxation of Trp synthase in the presence of monovalent cations, [Na.sup.+] and N[H.sup.4.sup.+], and [Na.sup.+] together with an allosteric ligand, benzimidazole (BZI).

Research into the role of active site water in the stereospecificity of enzymatic reactions is presented.