Studies of the Regan alkaline phosphatase isoenzyme in plasma from a lung-carcinoma patient.

We compared an alkaline phosphatase (EC 3.1.3.1) isoenzyme from a plasma sample of a patient with carcinoma of the lung, who was suspected of having the Regan-type isoenzyme, with placental serum alkaline phosphatase and with tissue preparations from placenta, liver, bone, and intestine. The placental and Regan phosphatases responded similarly to heat treatment and modification by various inhibitors, except that the Regan isoenzyme was more resistant to EDTA inactivation than was the placental serum alkaline phosphatase, but more sensitive than placental tissue alkaline phosphatase. Isoelectric focusing and Cellogel electrophoresis showed the Regan isoenzyme to have a mobility similar to that of the placental type. We conclude that the isoenzyme was of the Regan type and support the contention that the placental and Regan isoenzymes are products of the same structural gene, with small differences due to post-genetic modification.