title: 5-Methylthioribose kinase. A new enzyme involved in the formation of methionine from 5-methylthioribose.
abstract: The presence of a previously unidentified enzyme, tentatively designated 5-methylthioribose kinase, has been demonstrated in cell-free extracts of Enterobacter aerogenes. The enzyme catalyzes the ATP-dependent phosphorylation of 5-methylthioribose. ADP is one of the products of the reaction and, based on functional group analyses, the other product is 5-methylthioribose 1-phosphate. A 40-fold purified enzyme preparation has been obtained from a cell-free extract of E. aerogenes. Activity of the partially purified enzyme is totally dependent on the presence of a divalent cation and a sulfhydryl reagent. The substrate specificity of the enzyme is quite narrow, and the Km values for ATP and 5-methylthioribose are 7.4 X 10(-5) M and 8.1 X 10(-6) M, respectively. These results suggest that 5-methylthioribose kinase may be a primary enzyme involved in the recycling of the methylthio group of 5-methylthioribose back into methionine.
mesh_terms: D002413:Cations, Divalent; D004754:Enterobacter / Q000201:enzymology*; D004755:Enterobacteriaceae / Q000201:enzymology*; D007700:Kinetics; D008715:Methionine; D010770:Phosphotransferases / Q000302:isolation & purification / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor); D013865:Thioglycosides / Q000378:metabolism*
chemical_list: D002413:Cations, Divalent; D013865:Thioglycosides; C001955:5-methylthioribose; D008715:Methionine; D010770:Phosphotransferases; D017853:Phosphotransferases (Alcohol Group Acceptor); C021787:5-methylthioribose kinase