The brain glycine is almost exclusively derived from serine via serine-hydroxymethyltransferase. 17 males schizophrenic inpatients and 10 males healthy volunteers were submitted to the serine tolerance test. 2. Plasma serine and glycine concentration were evaluated before and after 1, 2, 3, 4 hours of an oral load with L-serine to test the interconversion between the two amino acids. 3. The authors did not find any significant difference between schizophrenic patients and control group and concluded that the enzyme serine-hydroxymethyltransferase is not deficient in the conversion of serine to glycine in schizophrenic patients as suggested by other authors.
