Liver acids

Prostate, red cell, and liver acid phosphatase will be discussed in detail because considerable data are available for these enzymes. 

In formalin-fixed rat liver, acid phosphatase activity is localized in peribiliary granules in the hepatic cells and in the Kupffer cells. The... 

Brightwell and Tappel (90) purified rat liver acid phosphatase from a lysosomal fraction by DEAE and CM-cellulose chromatography. Table XX (90) shows the specificity of the lysosomal enzyme. 

Mouse liver acid phosphatase is localized in the Kupffer cells in contrast to the alkaline phosphatase activity which is largely confined to the endothelial linings of the sinusoids. Under the conditions in which the activity of the reticuloendothelial system is enhanced, both enzymic activities are increased (97, 98). 

MacDonald (99) showed that mouse liver acid phosphatase required active sulfhydryl groups for activity and that malonate buffer, pH 5.9, was useful for the assay of this enzyme because it stabilized the enzyme during the period of the assay. 

Liver acid phosphatase has been of particular interest since the demonstration by de Duve (D7, D8, D9, DIO) that acid phosphatase and other hydrolytic enzymes were enclosed in an intracellular structure, the lysosome, of the liver and played an important role in the intra-... 

The liver acid phosphatase III thus isolated had a molecular weight of 14,000 daltons as determined by filtration through a column of Sephadex G-75 that had been calibrated with markers of known molecular weiglit, and a molecular weight of 16,500 daltons on the basis of sedimentation equilibrium analysis. With p-nitrophenyl phosphate as substrate, the pH optimum was 5.5 and the Michaelis constant was 0.75 mM. The stability of the enzyme at 25° was dependent on pH and... 

Acid CEH has an optimum pH of 4.5 and is located within lysosomes (Fig. 1). Like many lipolytic enzymes, it is water soluble whereas its substrate is not. For this reason, devising a reliable assay method is difficult, and results should be viewed with caution [26,35]. Recently developed conditions foimd to yield satisfactory linearity with both time of incubation and enzyme concentration are 12.7 jitM cholesteryl oleate, dispersed in 1.27 mM egg PC 50 mM acetate buffer 2.0 mM sodium taurocholate 0.005% digitonin pH 3.9 [36]. In aortic cells these conditions gave an apparent of 1.5 /iM for cholesteryl oleate. It should be noted, however, that the nature, physical form, and molecular organization of the CE and associated molecules can have a critical effect on the activity of any preparation of CEH [37]. Rat liver acid CEH, for example, shows K s of 15.3, 14.3, and 7.3 jaM for cholesteryl oleate when the latter is present in vesicles, micelles, and emulsions, respectively [35]. 

N3-Phosphohistidine has been isolated from an alkaline hydrolysate of liver acid phosphatase (73) while N phosphohistidine has been isolated from prostate, placenta, and wheat germ acid phosphatases (74, 75). ]V3-Phosphohistidine is found in histone H4 (IV, F2al) (76). Phosphohistidines, substituted on either ring nitrogen atom, and c-N-phospholysine were isolated from a purified citrate cleavage enzyme (77). There is a good possibility that certain acidic nuclear proteins may contain e-iV-phospholysine and w-N-phosphoarginine (78). e-N-Phospholysine is present in histone I (FI) (78a). Phosphothreonine is found in certain proteins of which phosvitin is an example (79,80). 

Affinity chromatography of human liver acid /3-D-galactosidase Purification of /J-D-galactosidase from rat mammary gland... 

Affinity chromatography of acid ribonuclease 268 from He La cell lysosomes demonstration that the enzyme is a glycoprotein Purification of human liver acid a-D- 148... 

Affinity chromatography of human liver acid hydrolases... 

The isozymes of mammalian synthetase and the bacterial enzyme show similarities in subunit weight. TheE. coli enzyme was found to be a monomer of 56,000 daltons (37), and the rat liver acidic isozyme and the Novikofif ascites enzyme (45) have a molecular weight of 55,000-60,000. The A. vinelandii enzyme is a native dimer of 110,000 daltons (14) and the rat skeletal and Yoshida sarcoma enzymes are dimers of... 

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