Collect. Czech. Chem. Commun. 1987, 52, 1872-1877

Effect of modification of certain amino acid residues on enzyme activity of D-3-hydroxybutyrate dehydrogenase from bacterium Paracoccus denitrificans

Jan Kovář and Ivana Matysková

Department of Biochemistry, Faculty of Natural Sciences, J. E. Purkyně University, Kotlářská 2, 611 37 Brno


We examined the effect of several modifying reagents on the activity of the title enzyme. The results show that one histidine residue participates in the interaction of the enzyme with the substrate; one cysteine residue binds near to the nicotine amide moiety of the coenzyme molecule and its role is to induce conformational changes leading to the formation of enzyme aggregates with an increased catalytic power. The enzyme does not contain essential tyrosine and tryptophan residues. The results of the experiments with the modification of additional amino acid residues permit us to make preliminary conclusions only based on the knowledge of the protective effect of the individual ligands: One arginine residue may be involved in the binding of the coenzyme, the residues of lysine and serine may be localized in the substrate binding site.