Elementary steps of enzymatic oxidation of nifedipine catalyzed by horseradish peroxidase.

The elementary steps of the enzymatic oxidation of nifedipine (NF) catalyzed by horseradish peroxidase (HRP) have been described based on analysis of kinetic magnetic field effects (MFEs). It has been shown that the first step of the catalytic cycle is single electron transfer resulting in formation of NF*(+) radical cation and ferroperoxidase (Per(2+)). As a result, comparison with an earlier studied oxidation reaction of NADH catalyzed by HRP evidenced that the enzymatic oxidations of two substrates-native, NADH, and its synthetic analogue, NF-catalyzed by HRP in the absence of H(2)O(2) follow identical mechanisms.

Magnetic spin effects in enzymatic reactions: radical oxidation of NADH by horseradish peroxidase.

A description of the elementary steps of the horseradish peroxidase (HRP)-catalyzed oxidation of NADH is presented, along with a quantitative analysis of the magnetic-field dependence of the enzymatic reaction. In the absence of H(2)O(2), the catalytic cycle begins with single-electron transfer from NADH to native HRP to form the NADH(.+) radical cation and the ferroperoxidase intermediate (Per(2+)).