Purification and characterisation of the placental-like alkaline phosphatase from ovarian epithelial tumours.

The placental alkaline phosphatase was purified by immunoaffinity chromatography from ovarian epithelial tumours to homogeneity. Up to 40% of the catalytical phosphatase activity in these tumours was derived from this placental type alkaline phosphatase (PLAP). The purified enzyme were similar to those of PLAP, whereas the PLAP-like isozyme was more heat-stable and resistant to 8 M urea than PLAP. The amino terminal sequence of the PLAP-like enzyme demonstrated heterogeneity at position three in the N-terminal end compared with PLAP. Phenyl-Sepharose affinity chromatography and different lectin chromatographies demonstrated the tumour-derived enzyme to be microheterogeneous, both with regard to concanavalin A binding and hydrophobicity properties.