Abstract:

A class of mechanistic substrates has been applied for the mechanistic studies of aerobic and anaerobic enzymatic oxidations of hydrocarbons. Mechanistic studies of cytochrome P450 C-H bond hydroxylation reveal a radical mechanism and the possibility of a cationic intermediate deriving from an electron-transfer process by the originally formed radical intermediate. Mechanistic studies of T4MO (toluene 4-monooxygenase) by norcarane, 1,1-diethylpropane, 1,1-dimethylpropane reveal a similar conclusion as in P450s. These mechanistic probes have been further utilized in the studies of whole-cell cultures containing P450s and AlkB, which again demonstrate the same theory. Therefore, as a general rule, aerobic oxidations of hydrocarbons by biologically important systems are best described as a 'hydrogen abstraction and oxygen rebound' process.

These radical-clocks have been further utilized in the mechanistic studies of the classical Kharasch reaction and other biomimic important systems. Reaction mechanisms have been fully explored. The results demonstrate the accuracy and effectiveness of radical clocks.