INACTIVATION OF SEROTONIN BY SIJLFOTRANSFERASE SYSTEM

¹ Departments of Biochemistry and Pharmacology, School of Dentistry, Aichi-Gakuin University, Nagoya, Japan and institute of Biochemistry, Faculty of Medicine, University of Nagoya, Nagoya, Japan

Inactivation of serotonin due to its enzymic O-sulfation was demonstrated by testing its biologic activity with the preparation of isolated dog aorta or rabbit aorta. The change in tension of the aorta caused by serotonin was found to be decreased in proportion to the time of incubation of serotonin with the sulfating system, which was composed of a highly purified sulfotransferase and 3'-phosphoadenosine 5'-phosphosulfate generating enzymes. Authentic serotonin O-sulfate had no stimulating effect upon contraction of aorta at the concentration of 1 x 10^-6 M, though intense stimulation was produced by the same concentration of serotonin. The investigation on distribution of the sulfotransferase in tissues and organs revealed that the liver, lung, kidney, brain, heart and spleen, which contain serotonin, had the enzymic activity.