The Phosphatases of Human Erythrocytes

By HELEN QUINCY WOODARD, PH.D. V ARIOUS investigatorst5 have reported that erythrocytes exhibit phosphatase activity at pH values between 4 and 6, and some believe that this is due to two acid phosphatases with maximum activities at about pH 4.2. and .6. Reports on alkaline phosphatase activity have been less numerous.’ ‘ 6 , 7 In the course of an investigation of the glycerophosphatase activity of human erythrocytes the present author encountered difficulties with the experimental method which led to the discovery that erythrocytes contain a labile phosphorus compound which decomposes spontaneously as soon as the cells are hemolyzed. The decomposition is probably enzymatic, but, as its exact nature is not yet clear, it is here described only by the general term ‘ ‘autolysis. ‘ ‘ It is probable that some of the variations in phosphatase activity reported by previous authors were, in reality, due to vanations in the degree of autolysis which takes place under different experimental conditions . For instance, Be6 found considerable alkaline glycerophosphatase activity, but little alkaline phenylphosphatase activity. Since phenyl phosphatase is determined by measuring the amount of phenol liberated, the findings would not be confused by the presence of phosphate liberated by autolysis, as they would in the determination of glycerophosphatase. In the present report some of the properties of the autolytic process are described, and evidence is presented which suggests that the amount of the substance which undergoes autolysis may be increased in certain diseases.