Isolation and characterization of two immunochemically distinct alkaline phosphatases from Pseudomonas aeruginosa

We have isolated two alkaline phosphatases (H-AP and L-AP, for high and low molecular mass, respectively) from Pseudomonas aeruginosa PA01. These two enzymes were found to differ in mobility on sodium dodecyl sulphate polyacrylamide gels (H-AP, M(r) = 51,000 and L-AP, M(r) = 39,500), amino-terminal amino acid sequence and did not cross-react. Both enzymes were active as phosphomonoesterases while only L-AP demonstrated any phosphodiesterase activity. Both enzymes were purified from P. aeruginosa grown in phosphate limiting conditions using the same protocol and were identified in both periplasmic and extracellular locations. A low level of H-AP was produced constitutively whereas L-AP was produced only after induction by reduced phosphate concentration in the growth medium. An L-AP-like enzyme has been previously described, however, this is the first report of a second P. aeruginosa alkaline phosphatase.