Hyperglycinemia. V. The Miscible Pool and Turnover Rate of Glycine and the Formation of Serine*

Abstract
The metabolism of glycine was studied by using glycine-2-H3 in a patient with idiopathic hyperglycinemia and in 4 controls. The glycine pool in the patient was approximately twice as large as in the controls. Since the rates at which these pools turned over was similar, the total turnover in the patient was twice as great in g of glycine/day as in the controls. Among the amino acids beside glycine, only serine was labeled. Its formation from glycine was markedly less efficient in the patient. These data suggest that there is a fundamental abnormality in hyperglycinemia in the conversion of glycine to serine.