Erythrocyte enzymes

Red blood cells also contain sufficient acid phenylphospha-tase for mild hemolysis to cause false elevations. Therefore, inhibitors such as ethanol, formaldehyde, copper sulfate> and 1-tartrate have been used to inhibit selectively the enzyme of one or more tissues and enhance the specificity of the test (101). Ethanol is unsuitable because it inhibits the enzyme from erythrocytes and prostate simultaneously, and because it yields serum activities which correlate poorly with prostatic disease. Formaldehyde inhibits the erythrocytic enzyme and has been said to yield clinically satisfactory results. The copoper resistant acid phosphatase of serum is elevated by metastatic carcinoma of the breast, as well as by other metastatic cancers, and is also elevated by a wide variety of non-cancerous diseases. 

Establish the validity of using two specific erythrocyte enzyme measurements as sensitive indicators of very low body burdens of lead and other heavy metals... 

Paglia DE, Valentine WN, Dahigren JG. 1975. Effects of low-level lead exposure on pyrimidine 5 -nucleotidase and other erythrocyte enzymes Possible role of pyrimidine 5 -nucleotidase in the pathogenesis of lead-induced anemia. J Clin Invest 56 1164-1169. 

A.A. Khan, M.M. Schuler, and R.W. Coppock, Inhibitory effects of various sulfur compounds on the activity of bovine erythrocyte enzymes. J. Toxicol. Environ. Health 22, 481-490 (1987). 

R. van Wijk and W. W. van Solinge, The energy less red blood cell is lost Erythrocyte enzyme abnormalities of glycolysis. Blood 106(13), 4034 4042 (2005). 

Thus a distinction was provided between simple esterases, such as fiver esterase, which catalysed the hydrolysis of simple aliphatic esters but were ineffective towards choline esters. The term 1 cholinesterase was extended to other enzymes, present in blood sera and erythrocytes of other animals, including man, and in nervous tissue, which catalysed the hydrolysis of acetylcholine. It was assumed that only one enzyme was involved until Alles and Hawes2 found that the enzyme present in human erythrocytes readily catalysed the hydrolysis of acetylcholine, but was inactive towards butyrylcholine. Human-serum enzyme, on the other hand, hydrolyses butyrylcholine more rapidly than acetylcholine. The erythrocyte enzyme is sometimes called true cholinesterase, whereas the serum enzyme is sometimes called pseudo-cholinesterase. Stedman,3 however, prefers the names a-cholinesterase for the enzyme more active towards acetylcholine, and / -cholinesterase for the one preferentially hydrolysing butyrylcholine. Enzymes of the first type play a fundamental part in acetylcholine metabolism in vivo. The function of the second type in vivo is obscure. Not everyone agrees with the designation suggested by Stedman. It must also be stressed that enzymes of one type from different species are not always identical in every respect.4 Furthermore,... 

Because of the possibility of hemolytic anemia caused by immature erythrocyte enzyme systems (glutathione instability), the drug is contraindicated in pregnant patients P.1001... 

Erythrocyte enzymes Glucose-6-phosphate dehydroge nase (G-6-PD) 250-5000 units/10 cells 250-5000 mcunits/cell... 

Besley GTN (1987) Phosphorylase b kinase deficiency in glycogenosis type VIII differentiation of different phenotypes and heterozygotes by erythrocyte enzyme assay. J Inherit Metab Dis 10 115-118... 

Narisawa K, Arai N, Hayakawa H, Tada (1981) Diagnosis of dihydropteridine reductase deficiency by erythrocyte enzyme assay. Pediatrics 68 591-592... 

Efficacy Autologous HSC gene therapy and non- myeloablative conditioning in two conditioning in two ADA-SCID patients In both patients, the number of PBLs, serum IgM, IgA and IgG levels, mRNA expression of the ADA vector, intracellular ADA enzymatic activity in PBLs, and erythrocyte enzyme activity indicated a reconstitution of -cell functions, as well as an amelioration of the metabolic pattern. 515130... 

Milk contains trace amounts of SOD which has been isolated and characterized it appears to be identical to the bovine erythrocyte enzyme. SOD inhibits lipid oxidation in model systems. The level of SOD in milk parallels that of XO (but at a lower level), suggesting that SOD may be excreted in milk in an attempt to offset the pro-oxidant effect of XO. However, the level of SOD in milk is probably insufficient to explain observed differences in the oxidative stability of milk. The possibility of using exogenous SOD to retard or inhibit lipid oxidation in dairy products has been considered. 

Heavy metals stimulate or inhibit a wide variety of enzyme systems (16, 71, 72), sometimes for protracted periods (71, 73). These effects may be so sensitive as to precede overt toxicity as in the case of lead-induced inhibition of 8 ALA dehydrase activity with consequential interference of heme and porphyrin synthesis (15, 16). Urinary excretion of 8 ALA is also a sensitive indicator of lead absorption (74). Another erythrocytic enzyme, glucose-6-phosphatase, when present in abnormally low amounts, may increase susceptibility to lead intoxication (75), and for this reason, screens to detect such affected persons in lead-related injuries have been suggested (76). Biochemical bases for trace element toxicity have been described for the heavy metals (16), selenium (77), fluoride (78), and cobalt (79). Heavy metal metabolic injury, in addition to producing primary toxicity, can adversely alter drug detoxification mechanisms (80, 81), with possible secondary consequences for that portion of the population on medication. 

Inhibition of the chicken breast enzyme by rabbit antisera for chicken breast enzyme the lack of effect on the chicken brain, heart, or erythrocyte enzyme and the differences in substrate specificity exhibited by the brain and breast muscle enzyme are consistent with at least two isozymes of chicken 5 -AMP aminohydrolase (123). Isozymic patterns, while perhaps implied by differences in certain kinetic pa-... 

In the absence of activators AMP aminohydrolase from brain (149), erythrocytes (143, 150), muscle (145), and liver (128) gave sigmoid curves for velocity vs. AMP concentration which were hyperbolic after the addition of monovalent cations, adenine nucleotides, or a combination of monovalent cations and adenine nucleotides. For the rabbit muscle enzyme (145), addition of K+, ADP, or ATP produced normal hyperbolic saturation curves for AMP as represented by a change in the Hill slope nH from 2.2 to 1.1 Fmax remained the same. The soluble erythrocyte enzyme and the calf brain enzyme required the presence of both monovalent cations and ATP before saturation curves became hyperbolic. In contrast, the bound human erythrocyte membrane enzyme did not exhibit sigmoid saturation curves and K+ activation was not affected by ATP (142). 

An alkaline pyrophosphatase from rat liver cytoplasm has been partially purified and characterized (24) the corresponding enzyme from mice is inhibited by Mg J+-ADP and free PPj, and free Mg2+ has been implicated as an allosteric activator (23). Partial heat inactivation results in loss of the apparent allosteric effects. Rat liver mitochondrial pyrophosphatase, which is inhibited by adenine nucleotides (36), appears to be bound to the inside of the inner mitochondrial membrane (37). This enzyme, after solubilization, has been separated into two fractions which have somewhat different specificity (24, 38). A pyrophosphatase strongly simulated by sulfhydryl reagents (39) has been partially purified from brain tissue (40). The mono-magnesium PPj complex appears to be the true substrate for this enzyme (41). Pynes and Younathan have purified a pyrophosphatase 1800-fold from human erythrocytes (43). The properties of this enzyme are strikingly similar to those of the yeast enzyme the major difference appears to be the more rigid substrate specificity of the erythrocyte enzyme in the presence of Znz. ... 

OPs have been in use for several decades as important chemicals for the control of crop pests. With their chemical and biochemical reactions, OPs have been well established as extremely poisonous chemicals. This classification is due to the inhibition of the marker enzyme ChE, which is produced in the liver. Blood enzymes provide an estimate of tissue enzyme activity. After acute exposure to OPs or a nerve agent, the erythrocyte enzyme activity most closely reflects the activity of the tissue enzyme. Once the OPs inhibit the tissue enzyme, it cannot hydrolyze ACh, and the accumulation stimulates the affected organ. Based on the manner of exposure (dose and duration) to different OPs, a series of toxicity signs and symptoms set in the organism, leading to death. These are important aspects to be closely monitored among pest control operators and occupational workers exposed to OPs. 

In the pyrimidines, a mammalian erythrocyte enzyme, pyrimidine phosphoribosyltransferase, converts uracil, orotic acid, and thymine into nucleotides as follows ... 

Bayar Sumer (1995) investigated the effect of some local anesthetics on methemoglobin levels and erythrocyte enzymes. 

Anderson KE (1978) Effects of antihypertensive drugs on hepatic heme biosynthesis, and evaluation of ferrochelatase inhibitors to simplify testing of drugs for heme pathway induction. Biochem Biophys Acta 543 313-327 Bayar C, Sumer N (1995) The effect of some local anesthetics on methemoglobin levels and erythrocyte enzymes. Turk J Med Sci 26 439-443... 

Today, biochemical deficiency of riboflavin is accepted in the absence of clinical signs of deficiency. Biochemical signs of deficiency include change in the amount of the vitamin which is excreted in the urine, or change in the level of activity of a red blood cell (erythrocyte) enzyme, which is known as the erythrocyte glutathione reductase. Requirements for the vitamin are defined as that amount which will prevent both clinical and biochemical signs of deficiency. 

The three enzymes are quite specific for their respective pyridine nucleotide substrates. Under conditions normally used for assay, lipoamide dehydrogenase is less than % as active with NADPH as with NADH IS) and thioredoxin reductase is less than 1% as active with NADH as with NADPH 36, Sff). Lipoamide dehydrogenase can transfer electrons to a number of NAD analogs 37). Yeast glutathione reductase is quite specific for NADPH 60), but the erythrocyte enzyme is 20% as active with NADH as with NADPH under the conditions of the standard assay 30,40,61). 

The yeast enzyme, like the erythrocyte enzyme, is inhibited by NADP and the inhibition is competitive with NADPH 252-254). The inhibition is rather weak, the inhibition constant being at least 10-fold higher than the K,n for NADPH. On the basis of these studies a mixed mechanism... 

Kinetic constants for the yeast enzyme are remarkably like those for the erythrocyte enzyme Fmax = 16,000 moles NADPH per min per mole of FAD, K (NADPH) - 3.8 /JW and, K (GSSG) = 55 Specific anion effects on the yeast enzyme have been interpreted to indicate two anion binding sites near the active site (257). 

Adsorption of the eel enzyme to the affinity column was quantitative and approx. 80% of the activity was recovered after elution with the inhibitor tensilon. Specific activity of the enzyme which migrated on disk electrophoresis as a single band was 16 000 units/mg. Results with the erythrocyte enzyme were equally good, with a 2500-fold purification achieved. 

Type II reactions are mimicked by the haemolysis induced by drugs (some antimalarials, sulpho-namides and oxidising agents) and food (broad beans) in subjects with inherited abnormahties of erythrocyte enzymes or haemoglobin (see p. 123). 

It is of interest that within several years after the observations of Hopkinson et al. (H13), other human erythrocytic enzymes such as phosphoglucomutase, glucose 6-phosphate dehydrogenase, phosphogluco-nate dehydrogenase, adenylate kinase, peptidase, and adenosine deaminase were explored intensively with respect to their polymorphism (H2, HU). However, we shall concern ourselves here only with acid phosphatase. 

Hll. Hopkinson, D. A., Genetically determined polymorphisms of erythrocyte enzymes in man. Advan. Clin. Chem. 10, 21-80 (1968). 

Genetically Determined Polymorphisms of Erythrocyte Enzymes in Man D. A. Hopkinson... 

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