THE FORMATION OF S-ADENOSYLMETHIONINE IN YEAST

Abstract

In a recent series of investigations on biological methyl group transfer, Cantoni and his coworkers (1, 2) have prepared S-adenosylmethionine from adenosine triphosphate and methionine by incubation in the presence of liver enzymes; from their work it appears that adenosylmethionine acts as a methyl donor in several enzymatic reactions in which this function formerly had been attributed to methionine.In a simultaneous series of papers the metabolic relation between methionine and methylthioadenosine in yeast has been studied; the formation of a thionium compound, adenosylmethionine, and its decomposition to methylthioadenosine and homoserine were suggested as an explanation of the isolation of the nucleoside from yeast which had been cultivated in a medium containing methionine (3,4).Data in the present report substantiate the concept of formation of a thionium compound from methionine in yeast and show its identity with S-adenosylmethionine.The high yield of methylthioadenosine from yeast indicated that the precursor, S-adenosylmethionine, may be obtainable from this source in a similar concentration.This was borne out by our experiments, and it would appear that yeast from cultures suitably supplemented with organic sulfur compounds is the source of choice for isolation of S-adenosylmethionine.Directions for the analysis of this compound are given, and some of its properties are described.