Distribution of Acid Phosphatase

The acid phosphatase appeared to be associated in the saclike structure with other hydrolytic enzymes, such as 3-glucuronidase and cathepsin, which also acted optimally at acid pH levels. Further studies were undertaken to isolate this structure (A13, G2). By means of a differential centrifugation procedure which will be described in detail later, de Duve and his associates (D9, DIO) determined the intracellular distribution of total and free acid phosphatase activity and of other enzymes as well. The mean values, expressed as percent of total acid phosphatase activity, were nuclear, 3.6 mitochondrial, 24.1 light mitochondrial, 40.7 microsomal, 20.1 final supernatant, 13.3. 

Using electron microscopy, Novikoff et al. (N6) found that rat liver fractions rich in these lysosomal enzymes, particularly acid phosphatase, showed the presence of mitochondria but had a predominance of single-membrane-limited bodies which were generally electron dense. Fractions with a low acid phosphatase activity rarely showed dense bodies. This observation provided some correlation between the biochemical concept of lysosomes and the existence of a structural unit within the cell (S28). 

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Distribution of Acid Phosphatase Components in the Tissues of 14 Different Individuals0 6... 

De Jong, D.W. (1965). Histochemical demonstration of extracellular distribution of acid phosphatase in onion roots. Phyton 22, 141-6. 

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. 

An approximate idea of the distribution of acid phosphatase activity in human tissues, regardless of the nature of the acid phosphatase, may be obtained from the studies of Reis (R2) on 5 -nucleotidase and other phosphomonoesterases. He prepared aqeuous homogenates of postmortem tissue in the proportion of 20 parts of water to one of tissue, allowed these to autolyze for 2 days at room temperature, centrifuged the material, and employed the supernatant fluid. The assay mixture consisted of 0.4 ml of a suitable buffer, 0.1 ml of 0.005 Af phenyl phosphate as substrate, and 0.1 ml of tissue extract. The enzyme activity was expressed as micrograms of phosphorus hydrolyzed per hour per milligram of wet... 

Of several methods that are potentially available for determining the intracellular distribution of acid phosphatase and other enzymes, the chief ones currently in use are ultracentrifugal separation and histochem-ical examination. Each of these has its disadvantages and advantages, some of which have already been indicated. At this point we will consider the quantitative ultracentrifugal methods. 

Intracellular Distribution of Acid Phosphatase in Other Tissues... 

Attempts to determine the intracellular distribution of acid phosphatase in the prostate must take into account the presence of this enzyme in the extracellular secretion. Employing centrifugal methods, Siebert et al. (S20) found that of the total acid phosphatase present in bull prostate homogenate, 0.7% was in the nuclear fraction, 41% in the mitochondrial fraction which presumably included the lysosomal component, and 84% in the microsomal and supernatant components. The finding that the sum of these activities exceeded that in the homogenate was considered to represent removal of inhibitors during separation of the fractions. 

The intracellular distribution of acid phosphatase in the ventral prostate of the rat has also been investigated by Bertini and Brandes (B15). Groups of male rats of two weight levels, 350 20 g and 180 10 g... 

The character of the intracellular distribution of acid phosphatase in the testis appears to differ from that in the kidney or liver, where a major portion of the enzyme is in the lysosomal fraction. Although the finding in the testis may represent a difference in cellular organization, the possibility also exists that the acid phosphatase may be less firmly bound to the lysosomal structure in the testis than in the liver and may be more readily solubilized during the process of homogenization. 

Kl. Kalina, M., and Bubis, J. J., Histochemical studies on the distribution of acid phosphatase in neurones of sensory ganglia light and electron microscopy. Histo-chemie 14, 103-112 (1968). 

R9. Russo, J., Subcellular distribution of acid phosphatase in the mouse testis. Ada Physiol. Lat. Amer. 20, 78-80 (1970). 

Fig. 4. EflFects of Triton WRl 339 injection on the equilibrium density of rat-liver lysosomes in a sucrose gradient as ascertained by the distribution of acid phosphatase and acid deoxyribonuclease. Solid line control animaL Broken line Triton WRl 339 treated animal. (After Wattiaux, Wibo and Baudhuin, 1963 and Wattiaux, 1%6.)...

Fig. S. Distribution, of acid phosphatase and giucose-6-phosphataae activity in sub-fractions of homogenate frctn human liver shown in relation to the capacity of Uie subfractions for stimulating m.ierosoraal synthesis of tauro- and glyeocholie acids. C— , Synthesis-increasing capacity, m/jmoles conjugates/mg protein from the respective fractions added to basal quantity of microsome protein. ---- , Acid phosphatase activity. Glucose-S hosphataae activity. N, nuclear fraction ...

Comparative distribution of acid phosphatase, nonspecific esterase and /3-glucuronidase in the placenta and fetal membranes (Christie, 1968) and some aspects of protea.se and /3-glucuronidase in the placental formation in rats have been reported by Autuori (1967). 

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