5′‐Methylthioadenosine Nucleosidase
Open Access
- 1 February 1981
- journal article
- research article
- Published by Wiley in European Journal of Biochemistry
- Vol. 114 (2) , 293-299
- https://doi.org/10.1111/j.1432-1033.1981.tb05148.x
Abstract
5′-Methylthioadenosine nucleosidase (EC 3.2.2.9), the enzyme which catalyzes hydrolytic cleavage of 5′-methylthioadenosine with the formation of adenine and 5′-methylthioribose, has been purified to homogeneity from Lupinus luteus seeds. The nucleosidase has a native molecular weight of 62000 and consists of two identical subunits, as judged by gel filtration and dodecylsulfate/polyacrylamide gel electrophoresis. The nucleosidase exhibits highest specificity towards the natural substrate with a Km of 4.1 × 10−7 M for 5′-methylthioadenosine. It does not cleave adenine from S-adenosylhomocysteine. Among the synthetic analogs of 5′-methylthioadenosinc tested, eleven compounds appear to be able to substitute as substrates. Furthermore, the enzyme can liberate hypoxanthinine from six inosyl (deaminated) derivatives obtained by enzymatic deamination of 5′-methylthioadenosine and its synthetic analogs. The Km for 5′-methylthioinosine is 55 μM, and the maximal velocity about 50-times lower than for 5′-methylthioadenosine. The reaction catalyzed by the nueleosidase can be inhibited by adenine (Ki= 11 μM), 3-deazaadenine (Ki= 19 μM), and 9-erythro(2-hydroxyl-3-nonyl)adenine (Ki= 37 μM).This publication has 48 references indexed in Scilit:
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