SEPARATION OF TISSUE AND SERUM ACID-PHOSPHATASE ISOENZYMES BY ION-EXCHANGE COLUMN CHROMATOGRAPHY

Abstract

A simple, rapid ion-exchange column-chromatographic technique for separating the acid phosphatase (EC 3.1.3.2) isoenzymes in human serum and tissue is described. Extracts of platelets, spleen, liver, erythrocytes and prostate were used to determine optimum conditions for separating these isoenzymes. Samples layered on mini-columns of DEAE-Sephadex A-50 were eluted stepwise with NaCl (100, 200 and 300 mmol/l, buffered with tris(hydroxymethyl)aminomethane). Activity in column effluents was measured with p-nitrophenol phosphate as substrate, and their isoenzyme content was assessed by electrophoresis on polyacrylamide gel. Comparison of activity patterns so derived for various tissues revealed prostatic tissue to be a rich source of acid phosphatase isoenzyme 2 activity. Evaluation of sera from 6 patients with prostatic cancer revealed isoenzyme patterns with prominent amounts of isoenzyme 2 (3.8-27.6 U[units]/l). Sera from 10 healthy laboratory technicians contained isoenzyme 2 in the range of 0.3-0.5 U/l. Samples from 2 patients with abnormally high activity owing to nonprostatic conditions (Gaucher''s disease and carcinoma of lung) exhibited < 2 U of isoenzyme 2/l and acid phosphatase isoenzymes 3-5 that were 50- to 100-fold the normal range. Quantification of isoenzyme 2 by DEAE-Sephadex column chromatography as described appears to provide a more sensitive and specific approach to diagnosis of prostatic cancer.