Glycerophosphates prostatic

In 1924, Martland et al. (1) reported on phosphatase activity in red blood cells. Roche later differentiated between the phosphatase of the red cells with pH optimum 6.0-6.2 and the phosphatase from white cells with optimum 8.8-9.0. Roche also showed that a-glycerophosphate was split more rapidly than -glycerophosphate by red cell extracts while the reverse was true of acid phosphatase activity in plasma (2). While studying the source of acid phosphatase activity in male urine, Kutscher and Wolberg discovered the very high activity of acid phosphatase in human prostate (3). This tissue was shown by Woodard to have one-thousand times the activity of extracts from bone, liver, and kidney (3a). Igarashi and Hollander crystallized the acid phosphatase of rat liver and showed that under certain conditions allosteric control of the activity could be demonstrated (4). 

Fig. 1. Prostatic acid phosphatase activity as a function of pH ( ) phenyl phosphate (O) p-nitrophenyl phosphate and (A) /8-glycerophosphate. Buffers Ac, acetate Cit, citrate and tris. From Nigam et al. (88).

Fia. 7. Inhibition of prostatic acid phosphatase by D-(+)-tartaric acid. The reaction mixtures all contained equivalent amounts of the enzyme preparation, the indicated concentration of substrate (pH 5.0), 0.05 iff acetate buffer (pH 5.0), and tartaric acid (pH 5.0) total volume, 4.5 ml. Each point represents average values of determinations made with 5 X 10-5 iff and 10 X 10"5 iff tartaric acid except in the case of /3-glycerophosphate for which 1 X 10 iff and 2 X 10 iff tartaric acid was used. From Kilsheimer and Axelrod (4 ). 

Relative Rates of Hydrolysis of a- and /3-Glycerophosphates and Phenyl Phosphate by the Acid Phosphatases of the Prostate and Red Cells 1... 

The question may arise as to which is the preferred method. In the author s experience, and this will be documented more completely later, the use of the substrate, sodium (S-glycerophosphate, as in the Bodansky procedure (B18, 32), is more specific for elevations of serum acid phosphatase activity due to prostatic carcinoma. However, the use of other substrates, such as sodium phenyl phosphate in the Gutman method (GIO, G14), may elicit alterations of activity in the serum that reflect diseases in other tissues. 

Study of the distribution of acid phosphatase in different tissues is burdened by indications that there are several acid phosphatases. Even the older literature indicated the nonidentity of acid phosphatases of different origin. In 1934, Davies (D4) showed that the acid phosphatase in the red cell hydrolyzed a-glycerophosphate more readily than )8-glycerophosphate, whereas the reverse was true for the acid phosphatase from spleen. Kutscher and Wolbergs (K12) found that prostatic acid phosphatase was inactivated irreversibly by various narcotics, including alcohols. 

The relative rates of hydrolysis of several substrates were determined at 37°C and pH 5.0 and expressed as milligrams of phosphorus liberated in 30 minutes per 100 ml of a diluted enzyme preparation. For 0.02 Af yS-glycerophosphate in the absence of any added Mg these rates were 0.2 for erythrocytic phosphatase and 29 for prostatic phosphatase. The corresponding rates were 11 and 28 with 0.02 M a-glycerophosphate as substrate, and 55 and 53 with 0.005 M phenyl phosphate as substrate. The presence of Mg activated the rates of hydrolysis to only a small degree. Thus, it may be seen that the use of /8-glycerophosphate as substrate distinguished sharply between the erythrocytic and prostatic phosphatases. 

Reaction velocities were determined at various concentrations of a-glycerophosphate and of phenyl phosphate at pH 5.5 and 37° with 0.1 M acetate as buffer and 0.001 M EDTA. A Lineweaver-Burk plot yielded a value of 7 mM for the Michaelis constant with a-glycerophos-phate as substrate and 0.9 mM with phenyl phosphate as buffer. It will be recalled that the corresponding values for human prostatic phosphatase were 3.1 mM and 0.15 mM according to Tsuboi and Hudson (T3). Nigam et al. (N3) had obtained a value of 0.75 mM for phenyl phosphate. In view of the experimental errors inherently involved in the determination of Michaelis constants leading frequently to coefiBcients... 

In addition to the studies cited above, there are several others showing that phenyl phosphate is much more readily hydrolyzed than j3-glycerophosphate by acid phosphatase from human erythrocytes, whereas no such marked difference exists with respect to human prostatic phosphatase (B2, Tl, T3). Unfortunately, there do not appear to be any systematic investigations of the substrate-velocity relationship for the acid phosphatases of other human tissues. In general, the available data would indicate that /3-glycerophosphate is a more specific substrate than phenyl phosphate for the detection and assay of acid phosphatase coming from the prostate. 

There are a number of findings, the relation of which to the disease has not been established. A ten-fold elevation of serum acid phosphatase has been observed in a three year-old patient by Hastrup and Videbaek (1954). Since this enzyme differed from prostatic phosphatase by exhibiting a lower activity towards beta-glycerophosphate, it was similar to the acid phosphatase which is found elevated in Gaucher s disease and there is reason to doubt the diagnosis of NPD in this case. Elevation of serum acid phosphatase activity in NPD has not been found by other observers for instance the relevant values were normal on 11 occasions in six patients studied by Crocker and Farber (1958). 

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