Side chain hydroxilation of aromatic compounds by fungi. Part 5. Exploring the Benzyclic Hydroxylase of Mortiella isabellina

The active site topography of the hydroxylase enzyme of Mortierella isabellina ATCC 42613, which carries out the benzylic hydroxylation of toluene, ethylbenzene, and related compounds, has been explored. Operating in a whole cell biotransformation mode, this enzyme shows selectivity in substrate processing based on the nature, position and size of substituent side chains close to the site of hydroxylation. The result of determination of the yield and stereochemistry of hydroxylation of over twenty substrates and potential substrates, together with previously reported data, have been used to propose an active site model for the benzylic hydroxylase enzyme.