Cytosol 5'-nucleotidase from Artemia embryos. Purification and properties.

Cytosol 5'-nucleotidase (EC 3.1.3.5) has been purified near homogeneity from Artemia embryos. The enzyme cleaves preferentially IMP and GMP, and to a lesser extent other 5'-mononucleotides. The substrate-velocity plot was hyperbolic with GMP and sigmoidal with AMP. The hydrolysis of GMP is stimulated both by ATP and beta, gamma-methyleneadenosine 5'-triphosphate with the same activation constant of around 0.6 mM. Both nucleotides decreased S0.5 without affecting V. The molecular mass of the native purified enzyme was 165 kDa, and one major band of 42 kDa was detected after sodium dodecyl sulphate polyacrylamide gel electrophoresis.