Periplasmic nonspecific acid phosphatase II from Salmonella typhimurium LT2. Crystallization, detergent reactivation, and phosphotransferase activity

The periplasmic nonspecific acid phosphatase II from Salmonella typhimurium was purified to homogeneity from a mutant strain that overproduces the enzyme (Uerkvitz, W., and Beck, C.F. (1981) J. Biol. Chem. 256, 382-389). It was shown that the enzyme transfers phosphate groups from organic phosphoric acid esters (donors) to water as well as to the 2'-, 3'-, or 5'-hydroxyls of nucleosides, nucleotides, and other compounds with free hydroxyl groups (acceptors). The enzyme was crystallized in two forms by precipitation with polyethylene glycol. Needles were formed in buffer containing Mg2+, whereas thin rectangular plates appeared in the presence of the non-ionic detergent n-octyl glucoside. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis under partially or completely denaturating conditions revealed that the native enzyme is a tetramer consisting of identical 24-kDa monomers. Owing to surface inactivation, polyethylene glycol, non-ionic, or Zwitterionic detergents are indispensable for enzyme stability. The detergents are able to reactivate inactivated enzyme when present near or above their critical micelle concentration.