The mechanism of sulphide oxidation by <i>Mortierella</i><i>isabellina</i> NRRL 1757

Abstract

A series of aryl substituted phenyl and benzyl methyl sulphides has been oxidized to the corresponding sulphoxides by Mortierellaisabellina NRRL 1757. The oxygen atom introduced during this enzymic oxidation is derived from the atmosphere and not from water. The rates of oxidation have been determined by uv analysis, and correlated with the Hammett p sigma constants for the phenyl methyl sulphide series. The value of ρ = −0.67 so obtained is interpreted in terms of a mechanism of oxidation at sulphur involving an electrophilic attack on the sulphide sulphur by the enzymic activated iron–oxygen complex, followed by conversion of the resulting sulphur cation to sulphoxide.