Purification and properties of the adenosine deaminase from the midgut gland of a marine bivalved mollusc, Atrina spp.
1. The adenosine deaminase has an approximate molecular weight of 130,000-140,000 and the composition of two polypeptide units (mol. wt about 68,000) is suggested, by means of SDS disc electrophoresis. 2. Both the alpha (Vm/Km) and beta (Vm) parameters were varied with pH and temperature. RSS (relative substrate specificity) adenosine and deoxyadenosine values for alpha and beta were 1.2 and 1.1, respectively. 3. Adenine, 2'-, 3', 5'-AMP, 5'-deoxyAMP, ADP and ATP were not deaminated by the enzyme. 4. Inhibition by Mg2+ was found in reaction with adenosine at pH 8 but not with deoxyadenosine at the same pH. Mn2+, which did not affect the reaction rate at pH 4 and 5, showed competitive inhibitory effects at pH 6, 7 and 8.
D000243:Adenosine Deaminase / Q000302:isolation & purification* / Q000378:metabolism; D000818:Animals; D002850:Chromatography, Gel; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D008974:Mollusca / Q000201:enzymology*; D009700:Nucleoside Deaminases / Q000302:isolation & purification*; D013696:Temperature
D008345:Manganese; D009700:Nucleoside Deaminases; D000243:Adenosine Deaminase; D008274:Magnesium