The presented metabolic schemes demonstrate the interrelationships between S-adenosylmethionine and the final products of its enzymic splitting: the methyl group, homocysteine, and the usually omitted adenosine. Manifold concerted interactions and recyclations of those substances are graphically arranged to show their influence on the mutual co-ordination of transmethylation, sulphur and purine metabolisms, respiration, and energy generation. Loci of the inevitable participation of folates, cobalamins and pyridoxine are indicated. Deviations in those metabolic domains are shown to favour possible development of complementary symptoms of the syndrome of hyperhomocysteinaemia, now recognized as one of the important causative factors in atheroma formation, vascular obstruction, and heart disease. Dynamic relations between the citrate, purine and urea metabolic cycles through the dissociates of S-adenosylmethionine illustrate also the opposite functions of homocysteine and nitric oxide in regulation of cell metabolism.

        Key words: S-adenosylmethionine, folates, purine nucleotides, thiolic substances, hyperhomocysteinaemia.