Abstract

Catechol-O-methyltransferase, histamine-N-methyltransferase and a methanol-forming enzyme were identified in the red blood cells of humans and a variety of mammalian species. The properties of the transferase enzymes are described with respect to distribution in blood, co-factor requirements, products formed, species distribution and substrate specificity. The presence of the transferase enzyme in an easily accessible tissue in man makes possible a study of changes in these enzymes in different physiologic states, drug treatments and diseases.