PYROCATECHOLPHTHALEIN AS A SUBSTRATE FOR CATECHOLO-METHYLTRANSFERASE

Abstract

The incubation of pyrocatecholphthalein with S-adenosylmethionine in the presence of catechol O-methyltransferase produces a compound which can be colored by the addition of borate buffer, pH 10, and read at 595 mμ. The increase in color intensity is linear in relation to both time and enzyme concentration.Thin-layer chromatography indicates the production of two colored substances during incubation. If S-adenosylmethionine-methyl-14C is used as methyl donor, it can be shown that the colored substances are also labeled with methyl-14C. Synthetically prepared guaiacolphthalein migrates in the same way and exhibits the same visible spectrum. It is believed that the second spot is the phthalein derivative with one catechol and one guaiacol ring.The enzymatic methylation of catecholphthalein can be used as a rapid method for the determination of catechol O-methyltransferase.