Studies on human serum 5'-deoxy-5'-methylthioadenosine phosphorylase: molecular properties and clinical perspectives.

5? -Deoxy-5? -methylthioadenosine phosphorylase (MTAase) is the only enzyme responsible in eukaryotes for the removal of MTA, a natural sulfur nucleoside produced from S-adenosylmethionine (AdoMet) through several routes1, 2. The enzyme catalyzes the phosphorolytic breakdown of the N-C glycosidic bond of the thioether leading to adenine and 5-methylthioribose-1-phosphate (MTR-1-P)3, 4. The carbon skeleton of phosphorylated sugar (except C-1) is then recycled to methionine5 and the purine base is converted to adenosine 5 ?-monophosphate by adenine phosphoribosyltransferase1: MTAase, therefore, plays a key role in the control of both purine and amino acid pools.