[Guanidinoacetate-N-methyltransferase in epiphysis of mammals: stimulating effect of norepinephrine in vitro].

The activity of the enzyme of creatine biosynthesis, S-adenosylmethionine: guanidineacetate-N-methyltransferase (E. C. 2.1.1.2) is discovered in rat and bovine epiphysis homogenates. The enzyme activity was highest in epiphysis of immature and young rats and then decreased linearly with the animal age. No reliable activity of the enzyme was found in adult rats (200-300 g). Incubation of rat and bovine epiphysis with norepinephrine (10(-5)-10(-6) M) in the presence of S-adenosylmethionine and guanidineacetic acid resulted in the increase of the creatine synthesis rate.