Effects of normal and their branched alcohols with structurally minimal variation on kinetic parameters in thermolysin-catalyzed peptide hydrolysis and synthesis of N-(benzyloxycarbonyl)-L-phenylalanyl-L-phenylalanine and its methyl ester.

Article abstract of DOI:10.1271/bbb.59.535

When higher alcoholic solvents were added to the reaction medium, and the enhancement of the enzyme activity, followed by its reduction then inactivation, were observed in thermolysin-catalyzed peptide hydrolysis and synthesis. The organic solvent content used was less than the saturating concentration in the buffer (i.e., water-organic one-phase system). The kinetic parameters, Km and kcat, at the alcoholic concentration giving maximal enzyme activity in these reactions changed linearly with increasing logP values of the alcohols and consequently kcat/Km as well. When the branched isomers of alcohols with structurally minimal variation of which logP was equivalent theoretically, were used as annexments, the kinetic parameters were also changed. The results, especially the changes of Km for each organic solvent, suggested that each alcohol should act at the active site of the enzyme in its own effective mode.