Purification and some properties of tartrate-sensitive acid phosphatase from rabbit kidney cortex

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Abstract
Two forms of tartrate-sensitive acid phosphatases (EC 3.1.3.2) were purified from rabbit kidney cortex by a multiple-column-chromatography method. The basic form constituted 90% of the enzyme and migrated as a single band of protein on polyacrylamide-gel electrophoresis. The proteins contaminating the acidic form did not exceed 5% of the total protein. The specific activity towards p-nitrophenyl phosphate was 12 .mu.mol/min per mg for the basic form and 0.7 .mu.mol/min per mg for the acidic form. The basic form of the enzyme differs from the acidic form in its heat-stability, Km values, inhibition rates by tartrate and fluoride and substrate specificities. Relative to p-nitrophenyl phosphate hydrolysis rate, the acidic form hydrolyzed a variety of physiological monophosphate esters, whereas the basic form hydrolyzed only CMP and phosphoenolpyruvate. Bacterial neuraminidases had no effect on the activity and mobility of the acidic form on polyacrylamide-gel electrophoresis. Both forms have the same MW (101,000 .+-. 4000) and are probably composed of 2 identical subunits. The question of whether the 2 forms of the enzyme are different proteins or whether one is a modified form of the other is discussed.