It is generally accepted that ancient organisms must have possessed small genomes producing fewer gene products than contemporary organisms. Since the evolution of high specificity is surely a demanding process, primitive enzymes are likely to have been broad-specificity catalysts, utilizing a family of related substrates and producing a family of related products (67). Events of gene duplicati...

-Tyrosinase, tryptophanase and cysteine desulfhydrase were shown to catalyze a variety of a,—elimination, s—replacement and the reverse of the ct,—elimination reactions of amino acids. The mechanism f or these reactions was studied using the general mechanism for pyridoxal— dependent reactions. The enzyme—bound n—amino acrylate is the key intermediate. Enzymatic methods for preparing L—tyrosine...