The copper enzyme galactose oxidase (GOase, EC 1.1.3.9) catalyses the oxidation of D-galactose and other primary alcohols in air to the corresponding aldehydes and hydrogen peroxide. The current mechanistic hypothesis for this two-electron redox reaction involves a Cu(I)/Cu(II) couple and the reversible oxidation of a ligating phenolate (tyrosine residue of the Tyr272-Cys228 conjugate) to a phenoxyl radical. Our approaches to functional models for galactose oxidase comprise both the use of low-molecular-weight copper complexes of a Schiff-base and sulfonamide ligands, and the synthesis/screening of combinatorial libraries. With regard to the latter, we have synthesized (by the IRORI-directed synthesis approach) peptide libraries carrying either His or the redox-active amino acids Tyr, mod-Cys (a model for the Tyr272-Cys228 conjugate) or TOAC (a TEMPO-derived alpha-amino acid) at four variable positions. After incubation with copper ions, the catalytically active library members were identified by specially designed screening methods.

Novel steroids are obtained by reaction of 9,11-dehydro-dibenzylestradiol and dibenzylestradiol with phenyllithium in THF at room temperature.

Steroids Steroids U 0300Access to New Steroids via a (1,2) Wittig Rearrangement. -Novel steroids (II) and (IV) substituted by a hydroxylated arm at the 3-position are obtained by reaction of corresponding 3-benzylated estradiol derivatives with Ph-Li in THF. The reaction occurs probably according to a 1,2-Wittig rearrangement mechanism, that is hitherto not described for steroids. -(STEPHAN, E.; DOUSSET, M.; FOY, N.; JAOUEN, G.;