Quinone Tanning in the Animal Kingdom

Abstract

THE communication under the above title by Brown¹ prompts us to record that we have been engaged on the same problem from the chemical point of view during the past few years. Our approach was based on the assumption that combined tyrosine (in a protein) could be oxidized to combined 3 : 4-dihydroxyphenylalanine (I) [R = CH₂.CH(NH.COR′). CO.NHR′, where R′ is part of the protein residue], which might then undergo oxidation in either of two ways, namely: (i) direct hydroxylation of the benzene nucleus in the 6-position to give (II), (ii) oxidative elimination of R to produce hydroxyquinol (1 : 2 : 4-trihydroxybenzene) (III). In either case, a 1 : 2 : 4-trihydroxybenzene derivative would be produced.