Non-participation of Opal Suppressor Phosphoseryl-Transfer Ribonucleic Acid (tRNA) in Phosphoserine Aminotransferase catalysis

Abstract

The role of animal opal suppressor phosphoseryl-transfer ribonucleic acid (tRNA) as an intermediate in the metabolic pathway from 3- phosphoglycerate to glycine was studied. The labelled [³²P]phospho[³H]seryl-tRNA was prepared ahd used as a substrate in the reaction of bovine brain phosphoserine aminotransferase in the presence of α-ketoglutarare. On analysis of the reaction product, no 3-phosphohydroxypyruvate was found even though phosphohydroxypyruvate was obtained in the control experiment by use of phosphoserine and α-ketoglutarate. The aminotransferase did not react with phosphoserine methylester. These results show that the carboxyl residue on phosphoserine is essential for recognition by the aminotransfease. A role of phosphoseryl-tRNA as an intermediary metabolite from serine to phosphohydroxypyruvate is excluded.