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 sulfo xidize methyl S-benzyl-8-mercaptooctanoate as well as its naphthyl ana logue but the corresponding isomers where sulfur is bonded to the arom atic ring do not function as substrates. We have accounted for these r esults in terms of a conformational model. We have also accumulated so me evidence that suggests that dealkylation of these thia analogues do es not compete with sulfoxidation. Our recently discovered chiral shif t reagent (S)-(+)-alpha-methoxyphenylacetic acid (MPAA) can be used to determine the optical purity and absolute configuration of all sulfox ides prepared in this work.