STABILITY OF GLYCOSIDIC BOND OF S-ADENOSYLSULFONIUM COMPOUNDS TOWARD ACID

The acid hydrolysis of the biological sulfonium compound S-adenosylmethionine [S-(5′-deoxyadenosine-5′)-methionine] was studied and compared with that of S-adenosylhomocysteine [S-(5′-deoxyadenosine-5′)-homocysteine]. In 1 n HCl at 100 °, the sulfonium compound was found about two orders of magnitude more stable than the thioether. The sulfonium group accounts for the stabilization of the glycosidic bond of S-adenosylmethionine in acid, while S-adenosylhomocysteine resembles other purine ribosides in its facile acid hydrolysis. Attempts to isolate the pentose from S-adenosylmethionine were unsuccessful, but methionine could be isolated in nearly quantitative yield by hydrolysis for 4 hr in 6 n HCl at 100 °. The great difference in the acid stability of the sulfonium compound and the thioether permits the destruction of the latter in 1.5 n perchloric acid cell extracts by heating for 5 min at 100 ° which causes only 5% loss of S-adenosylmethionine. The procedure facilitates the analysis and isolation of S-adenosylmethionine. © 1969.