title: Kinetic properties and the effect of substrate analogues on 5'-methylthioadenosine nucleosidase from Escherichia coli.
abstract: 5'-Methylthioadenosine nucleosidase (EC 3.2.2-) from Escherichia coli has been purified 220-fold. A molecular weight of 31 000 for the enzyme was estimated from gel filtration on Sephadex G-150. The Km for 5'-methylthioadenosine was 3.1-10(-7) M. In addition to 5'-methylthioadenosine, the nucleoside analogues 5'-ethylthioadenosine, 5'-n-propylthioadenosine, and S-adenosyl-homocysteine also served as substrates for the enzyme. These substrate analogues acted as competitive inhibitors of the reaction with 5'-methylthioadenosine. The Ki values for 5'-ethylthioadenosine, 5'-n-propylthioadenosine, and S-adenosylhomocysteine were determined to be 1.3-10(-7) M, 4.6-10(-8) M, and 1.92-10(-7) M respectively.
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D008970:Molecular Weight; D009699:N-Glycosyl Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D009699:N-Glycosyl Hydrolases; D000241:Adenosine