[Absence of hydroxyindole O-methyltransferase, the terminal enzyme in melatonin synthesis, in the rat intestine].

The absence of hydroxinol-o-methyltrapherase, the terminal enzyme in the chain of melatonin biosynthesis in the gastrointestinal tract of rats was revealed by means of radioisotopic biochemical methods. A high endogenous methylation in the mucosa of the small intestine of rats with the participation of S-adenozylmethionine, differing from melatonin synthesis in the epiphysis, was revealed during this study.