Serine Transhydroxymethylase Activity in Vertebrate Retina

Abstract
The presence of serine transhydroxymethylase (STHM; EC 2.1.2.1) in crude homogenates of rat, guinea pig and goat retina has been demonstrated. There was a variation in the levels of retinal STHM activity in the three species. Substantial STHM activity was found in all the three retinal preparations in the absence of pyridoxal‐5‐phosphate in the incubation medium. There was direct correlation (r= 0.995; p < 0.001) between the STHM activity and the glycine content in rat telencephalon, midbrain, medulla‐pons, spinal cord and retina. These findings suggest that STHM is probably an important enzyme for the synthesis of neural glycine in the vertebrate retina.