Metal ion independent non-enzymic transamination between pyridoxal and amino acid esters

Abstract

In the absence of metal ions, a non-enzymic transamination reaction occurs, at 100° and pH 5.0, between pyridoxal and esters of leucine, alanine and glutamic acid. Pyridoxamine and keto acid esters appear to be formed, but the latter compounds are easily hydrolyzed to free keto acids. The reaction of pyridoxal with leucine isobutyl ester takes place readily at pH 5.0 to 7.0. The mechanism of this enzymic transamination is discussed in terms of the general mechanism proposed by Metzler et al. for pyridoxal-catalyzed reactions of amino acids.