Purification of human prostatic acid phosphatase by affinity chromatography and isoelectric focusing. Part I

The main isoenzyme of human prostatic acid phosphatases was purified by affinity chromatography on L(+)-tartrate linked to agarose and by isoelectric focusing. The enzyme was a single protein when examined by polyacrylamide gel electrophoreses, either as a native protein or in the presence of sodium dodecyl sulfate. The analytical recovery of enzyme activity was 19%. The specific activity was 40 18 mumol/(min X mg) for hydrolysis of 5.5 mmol/liter p-nitrophenyl phosphate at pH 4.8 and 37 degrees C. The purification factor was as great as 1900. The molecular weight of the enzyme as measured by gel filtration was 109 000 and by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate 54 000, indicating that the enzyme had been isolated in the dimer form. By this method we have achieved the best purification of human prostatic acid phosphatase so far.