The stability and hydrolysis of S-adenosylmethionine; isolation of S-ribosylmethionine.

Recent improvements in the methods for biosynthesis and isolation of S-adenosylmethionine (1, 2) have stimulated extensive experimentation with this compound. Detailed information upon its stability under various conditions is a prerequisite to microbiological, nutritional, and enzymatic research involving this substance. Not only is it desirable to have an estimate of the residual amount of X-adenosylmethionine at any given time during an experiment, but in many instances it is necessary also to know what fragments may accrue. Erroneous results may be surmised, especially in microbiological studies with mutants, if the response to hydrolytic products is mistaken for an effect of the parent substance. Experiments were carried out, therefore, on the stability of X-adenosylmethionine under the conditions of biological experimentation. Our study soon revealed that several hydrolytic processes occur simultaneously. To gain insight into the conditions which favor individual reactions, extremes of pH and temperature were included in this investigation. The latter phase of our work revealed conditions for splitting methionine from the molecule and for hydrolysis to adenine and a hitherto unknown fragment, S-ribosylmethionine. Directions for preparation and a description of some of the properties of this new compound are given. Our data extend the earlier observations of Cantoni, (3) and of Baddiley, Cantoni, and Jamieson (3, 4) on the hydrolysis of S-adenosylmethionine; they observed the formation of adenine by acid hydrolysis and of methylthioadenosine and homoserine by heating in neutral solution.