Manganese-dependent Production, and Properties, of 5'-Nucleotidase by Alkalophilic Bacillus No. A-59

Abstract

Alkalophilic Bacillus No. A-59 produced 5'-nucleotidase (EC 3.1.3.5) extracellularly when Mn²⁺ was added to the growth medium. The enzyme formation was negligible in the medium without the addition of Mn²⁺ and the optimum Mn²⁺ concentration for the enzyme production was 10 mM. The 5'-nucleotidase was purified and its molecular weight was determined to be 78, 000 by gel filtration. The optimum pH for its activity was 9.0 - 9.5. The enzyme was stable in the pH range of 8.5 to 9.5, and up to 40°C. A substrate specificity study revealed that the enzyme hydrolyzed 5'-AMP strongly, several 5'-XMPs and ADP weakly, but not 3'-XMP, 2'-XMP, ATP or p-nitrophenyl phosphate. The Km value for 5'-AMP was 1.5 mM. The maximum enzyme activity was obtained without divalent cations. The enzyme was inhibited by borate and arsenite ions, but not by 2mM EDTA.