Acid phosphatase marker enzyme

Acid phosphatases are enzymes that have been studied extensively due to the fact that their dysregulation is associated with pathophysiological conditions. This characteristic has been exploited for the development of diagnostic and therapeutic methods. As an example, prostatic acid phosphatase was the first marker for metastatic prostate cancer diagnosis and the dysregulation of tartrate resistant acid phosphatase is associated with abnormal bone resorption linked to osteoporosis. 

The lysosomes are the cell s stomach, serving to break down various cell components. For this purpose, they contain some 40 different types of hydrolases, which are capable of breaking down every type of macromolecule. The marker enzyme of lysosomes is acid phosphatase. The pH optimum of lysosomal enzymes is adjusted to the acid pH value and is also in the range of pH 5. At neutral pH, as in the cytoplasm, lysosomal enzymes only have low levels of activity. This appears to be a mechanism for protecting the cells from digesting themselves in case lysosomal enzymes enter the cytoplasm at any time. In plants and fungi, the cell vacuoles (see p. 43) have the function of lysosomes. 

Fig. 12. Diagram of elution pattern of red cell acid phosphatase and various markers on Biogel P 60. The position of the various protein markers was determined both by optical density determination and by starch gel electrophoresis of the individual fractions (83). The experiment was carried out using a polyacrylamide gel (Biogel P 60, 50-150 mesh exclusion limit >60,000 Bio-Rad Laboratories, California) in 0.05 M tris buffer, pH 8.0, containing 0.08% (v/v) Tween 80 and 0.1% (v/v) 2-mercaptoethanol to stabilize the enzyme. Column 60 X 4 cm. Flow rate 20 ml/hr, 4 ml fractions. (A) OD at 280 nm, ( ) OD at 540 nm, ( ) LDH assay with p-nitrophenyl phosphate for AcP. From Hopkinson and Harris (85).

Figure 9-14. Frequency distribution of various marker enzymes for lysosomes (acid phosphatase, cathepsin, etc.), peroxisomes (urate oxidase) and mitochondria (cytochrome oxidase). Mitochondrial fraction from rat liver centrifuged in a linear gradient of 0.25 to 0.5M sucrose. [From H. Beaufay et al., Biochem. /., 73 628 (1959).]...

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... 

Bone specific acid phosphatase A lysosomal enzyme of osteoclasts Urine Markers All of these are collagen breakdown products... 

The lysosomal acid phosphatase enzyme played a key role in the discovery of lysosomes by de Duve in 1963 and is widely used as a lysosomal marker. This enzyme shows a high degree of sequence similarity (ca. 49 % identity) with prostatic acid phosphatase [9] and both are inhibited by L-(+)-tartrate ion [10]. 

Since disturbed acid phosphatase activity has been associated with pathological conditions, the research has focused on the development of diagnostic methods for detection of activity as a marker for the onset of the disease, and in some extent to the development of inhibitors rather than activators to treat those conditions in which the increase in enzyme activity has a direct effect on the evolution of the disease. In particular, only the development of bisphospho-nate derivatives as inhibitors for tartrate-resistant acid phosphatase found their way to the market for treatment of osteoporosis [41], Typical inhibition of phosphatase activity includes anionic species such as L-(+)-tartrate, phosphate, vanadate, molybdate, and fluoride and neutral molecules such as formaldehyde. Vanadate ion,, is a competitive unspecific inhibitor for acid phosphatases by forming transition state analogs. Other oxoanions such as molybdate and tungstate also show inhibitory effects on... 

Tumour markers fall into one of several groups they may be homiones. e.g. human chorionic gonadotrophin (HCG) secreted by choriocarcinoma or enzymes, e.g. prostatic acid phosphatase in prostate carcinoma or tumour antigens. e.g. carcinoembryonic antigen (CEA) in colorectal carcinoma. 

However, the acid phosphatase activity of rat iiver lysosomes has recently been resolved into at least two enzymes [531]. Acid phosphatase is used in subcellular fractionation studies as a marker enzyme for lysosomes. Both acid phosphatase [E.C. 3.1.3.2] and alkaline phosphatase [E.C. 3.1.3.1] activities should not be confused with other specific phosphatases with high specificity requirements for substrate, e.g. glucose-6-phos-phatase, fructose-l,6-diphosphatase, phosphatidate phosphatase. Several assay procedures are available, u.v. estimation can be achieved using phosphoenolpyruvate as a substrate and lactate dehydrogenase in an indicator reaction [539]. Colorimetric assays can be based upon the liberation of phenol from phenylphosphate [540], upon the Uberation of phosphate from sodium /3-glycerophosphate [541], upon the hydrolysis of sodium phenolphthalein phosphate [542], or upon the hydrolysis of p-nitrophenyl phosphate [543]. 

Bioluminescent Enzyme Immune Assay (BLEIA), where the enzyme is the marker for the antigen of the immune reaction, which results in light emission. Markers are enzymes that are conjugated to bacterial luciferase, such as peroxidases, acid phosphatases and dehydrogenases. 

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