On the mechanism of hydrolysis of hydantoins by d-hydantoinase from Vigna angularis: inhibition studies

• Published in: Journal of molecular catalysis. B, Enzymatic Vol. 21; no. 3; pp. 107 - 111
• Main Authors: Arcuri, M.B, Sabino, S.J, Antunes, O.A.C, Oestreicher, E.G
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.01.2003; Elsevier Science
• Subjects: Biocatalysis; Bioconversions. Hemisynthesis; Biological and medical sciences; Biotechnology; d-Amino acids; d-Hydantoinase; Fundamental and applied biological sciences. Psychology; Methods. Procedures. Technologies; N-Carbamoyl- d-phenylglycine; Vigna angularis; Biocatalysis; Vigna angularis; d-Hydantoinase; d-Amino acids; N-Carbamoyl- d-phenylglycine; D-Hydantoinase; Enzyme; Dihydropyrimidinase; Hydantoins; D-Amino acids; Hydrolysis; N-Calbamoyl-n-phenylglycine; Leguminosae; Dicotyledones; Angiospermae; Hydrolases; Spermatophyta; Inhibition
• DOI: 10.1016/S1381-1177(02)00084-X
• ISSN: 1381-1177

Inhibition studies were performed with d-hydantoinase from Vigna angularis. These studies were based on the fact that 5,5-di-substituted hydantoins are not recognizable substrates for the enzyme. Rac-5-methyl-5-phenylhydantoin was shown to be an efficient competitive inhibitor of this d-hydantoinase ( K i=1.28 mM). ( R)-5-mono-substituted hydantoins were identified as the proper substrates of the enzyme. It is proposed that this reaction is constituted by a prior fast racemization step that provides the necessary and constant feeding of ( R)-5-mono-substituted isomer and a latter ( R)-specific enzymatic hydrolysis. The enzyme must present a hydrophobic environment in the pro- R face and a basic residue in the pro- S face. The feedstock configuration, its molecular volume and the presence of hydrogen in position 5 of the hydantoin are the main factors responsible for the substrate specificity showed by this enzyme.