Cobalt-requiring 5′-deoxy-5′-methylthioadenosine nucleosidase from soybean (Glycine max) cotyledon

5′-Deoxy-5′-methylthioadenosine nucleosidase (MTA nucleosidase, EC 3.2.2.9) was purified from soybean (Glycine max) cotyledon. The nucleosidase was a trimer consisting of three identical subunits with a molecular mass of 59.5 kDa. The nucleosidase was a cobalt-requiring enzyme for its catalytic function. The enzymatic activity increased in a dose-dependent manner in the presence of cobalt. Cobalt was bound to the nucleosidase with a stoichiometry of 1 equivalent of cobalt/subunit. A thiol group-specific reagent reduced the enzymatic activity. Four cysteinyl residues of each subunit are considered to play an important role in binding cobalt.