Add time:07/13/2019         Source:sciencedirect.com

Publisher SummaryThis chapter describes methods for preparation of S-adenosyl-methionine and corresponding derivatives. Like the mammalian liver, growing or metabolizing yeast synthesizes the corresponding S-adenosyl derivatives from methionine or ethionine in amounts ranging from 7 to 20 μmoles per gram of yeast, depending on the strain of yeast employed. The phosphotungstate of the S-adenosyl derivative, soluble in aqueous acetone, is decomposed with tetraethyl ammonium bromide or iodide, a step which completely removes the phosphotungstic acid. The bromide salt of the S-adenosyl derivative, after the adjustment of the pH to 5.8 with ammonia, is precipitated from methanolic solution with ethanol, washed with ethanol to remove all traces of tetraethyl ammonium bromide and NH4Br, then with ether, and dried in vacuo. The advantages of this procedure are that the salts of the S-adenosyl derivatives of methionine or ethionine can be prepared in any desired quantity in crystalline form, and that the salts are stable for indefinite periods when stored in vacuo over silica gel in the cold. The synthesis of S-adenosyl-L-methionine from S-adenosyl-L-homocysteine by methylation is also described in the chapter.

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