Kinetic Studies on the Interaction of D-Amino Acid Oxidase with Benzoate ando-Aminobenzoate

摘要

Kinetic studies on the interaction of D-amino acid oxidase D-amino acid: O2oxido-reductase (deaminating), EC 1. 4. 3. 3 with inhibitors, benzoate ando-aminobenzoate, which are considered to be substrate-substitutes of this enzyme, were performed by -using a stopped-flow spectrophotometric technique at pH8.2 and 15°C. The time course of the spectral change upon mixing the enzyme with either of the inhibitors is biphasic. The rapid change, which amounts to 93of the total change, is followed by a slow small one, which indicates the unhomogeneity of the uncomplexed enzyme. The application of the relaxation method to the rapid phase of the reaction revealed the two-step mechanism for the enzyme-inhibitor binding as follows,E+1==(EI)1==i(EI)2where the first step, E+I;=(EI)1is much faster than the second step, (EI)1==(EI)2, the spectral change occurring in the latter step