METHIONINE-ACTIVATING ENZYME IN STARFISH FOLLICLE CELLS

In starfish follicle cells 1-methyladenine is produced under the influence of a gonad-stimulating hormonal peptide (GSS). Since such production of the substance is enhanced by the addition of L-methionine or S-adenosylmethionine in vitro, the presence of methionine-activating enzyme in the follicle cells of the starfish, Asterina pectinifera, was investigated. To detect enzyme activity, the enzyme was partially purified from the supernatant of the follicle-cell homogenate by precipitation with ammonium sulfate followed by gel-filtration on a Sephadex G-150 column. Using such a preparation of the enzyme, the production of S-adenosylmethionine from L-methionine and adenosine triphosphate was clearly demonstrated by thin-layer chromatography. GSS was found to exert no effect on the activity of the methionine-activating enzyme. The hormonal peptide, GSS, is therefore considered to take part in some reaction other than this step in the formation of 1-methyladenine.