Conversion of 2-Hydroxy-4-(Methylthio)butanoic Acid to L-Methionine in the Chick: A Stereospecific Pathway

摘要: Conversion of 2-hydroxy-4-(methylthio)butanoic acid (HMB) to L-methionine (L-Met) was studied by using chick liver homogenates. The first step found be stereospecific with different enzymes for the D- and L-isomers HMB. L-HMB substrate L-2-hydroxy oxidase, a peroxide-producing flavo-enzyme in peroxisomes kidney. enzyme D-HMB, identified as mitochondrial D-2-hydroxy dehydrogenase, had not been previously described chick. This every tissue tested including intestinal mucosa skeletal muscle. Thus, D-HMB could used any organ protein synthesis, like L-Met itself. These results provide biochemical explanation equimolar incorporation HMB DL-methionine (DL-Met) into hepatocyte that two can simultaneously convert both isomers while only one enzyme, D-2-amino converts D-Met L-Met.