The kinetic characteristics of K228G mutant horse liver alcohol dehydrogenase

The kinetic constants and the reaction mechanism of the K228G mutant horse liver alcohol dehydrogenase isoenzyme E (HLADH-E) were compared to the wild -type enzyme. All the Km and Ki constants of the mutant enzyme for NAD(+), ethanol, acetaldehyde and NADH were larger than those of the wild-type enzy me. The dissociation constants for the NADH and NAD(+) (K-iq and K-ia) were greatly increased by 130- and 460-fold, respectively. The product inhibiti on patterns suggested that the reaction mechanism of the mutant enzyme was changed to Random Bi Bi. These results could attribute to the increase in t he dissociation rate of coenzyme with the substitution at Lys-228 residue.