Polyamine oxidase activity in human pregnancy serum.

The existence of a spermine oxidizing enzyme was established in human pregnancy serum by a radiochemical method, and a cross-sectional study of its quantitative profile between 10 and 40 weeks gestation was undertaken. Though there was a wide scatter of values, the rise in the average activity was continuous and highly significant. The flavoprotein inhibitor, quinacrin, inhibited the enzyme activity, while the pyridoxal phosphate inhibitor, isoniazid, had no significant inhibitory effect suggesting that the enzyme is of tissue origin. The possible role of polyamines and their oxidation in physiological immunoregulation is discussed.