Alkaline phosphatase and an acid arylamidase as marker enzymes for normal and transformed WI-38 cells.

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Abstract
A survey of eleven enzyme activity levels in normal and SV40 transformed (VA-13) WI-38 cells revealed that the transformed cell enzymes differed by a quantitative and qualitative change of alkaline phosphatase and a quantitative loss of an arylamidase. Alkaline phosphatase activity was found to be elevated in the transformed cells at confluency but not in log phase cultures. This elevated activity was heat stable, L-homoarginine resistant and L-phenylalanine sensitive and is probably the term placental isoenzyme. In nontransformed WI-38 cells, the alkaline phosphatase was heat labile, L-homoarginine sensitive and L-phenylalanine resistant and so is probably the liver isoenzyme. While the arylamidase activity from both normal and transformed WI-38 cells had identical pH optima and Km values, the activity was approximately 20 times higher in confluent WI-38 cells than in confluent VA-13 cells. Cytochemical staining techniques for both activities are described that permit identification of fluorescent product within the cells, analysis of activity levels, and separation of cells with high and low activities. Mixtures of WI-38 cells and VA-13 cells separated by flow cytometry on the basis of arylamidase activity were subsequently evaluated for alkaline phosphatase isoenzyme and found to have been simultaneously separated into heat labile and heat stable samples.