Isolation and purification of placental type alkaline phosphatase from a seminoma

An alkaline phosphatase (EC 3.1.3.1) of the placental type was isolated from a seminoma type of human testicular cancer tissue and was purified to homogeneity by sulfate-mediated chromatography on a column of Cibacron Blue Sepharose 4B. The purified enzyme had a specific activity of 40.6 kU per gram of protein and was obtained in a yield of 37%. The purification procedure used was simple and economical, and may be used to purify alkaline phosphatase isoenzymes from other cancer tissues. This is the first report of the purification of the enzyme in seminoma. Inhibition studies suggest that this enzyme is a Nagao variant rather than the Regan type reported in several cancer tissues.