S-Adenosylmethionine

S-Adenosyl-Lmethionine (SAM) is an important molecule in normal cell functi on and survival. SAM is utilized by three key metabolic pathways: transmeth ylation; transsulfuration; and polyamine synthesis. In transmethylation rea ctions, the methyl group of SAM is donated to a large variety of acceptor s ubstrates including DNA, phospholipids and proteins. Thus, interference of these reactions can affect a wide spectrum of processes ranging from gene e xpression to membrane fluidity. In transsulfuration, the sulfur atom of the SAM is converted via a series of enzymatic steps to cysteine. a precursor of taurine and glutathione, a major cellular antioxidant. Polyamines are re quired for normal cell growth. Given the importance of SAM in tissue functi on, it is not surprising that this molecule is being investigated as a poss ible therapeutic agent for the treatment of various clinical disorders., (C ) 2000 Elsevier Science Ltd. All rights reserved.