USE OF AROMATIC THIA FATTY-ACIDS AS ACTIVE-SITE MAPPING AGENTS FOR A YEAST DELTA(9) DESATURASE

The Delta(9) desaturating system of Saccharomyces cerevisiae can sulfoxidize methyl S-benzyl-8-mercaptooctanoate as well as its naphthyl analogue but the corresponding isomers where sulfur is bonded to the aromatic ring do not function as substrates. We have accounted for these results in terms of a conformational model. We have also accumulated some evidence that suggests that dealkylation of these thia analogues does not compete with sulfoxidation. Our recently discovered chiral shift reagent (S)-(+)-alpha-methoxyphenylacetic acid (MPAA) can be used to determine the optical purity and absolute configuration of all sulfoxides prepared in this work.