5 -Nucleotidase distribution

The biosynthesis of adenosine is theoretically controlled by several processes namely (1) the biosynthesis of adenosine from AMP by 5 -nucleotidase [EC 3.1.3.5], (2) from S-adenosyl homocysteine by S-adenosyl homocystine hydrolase [EC 3.3.1.1], (3) the metabolism of adenosine to AMP by adenosine kinase [EC 2.7.1.20], and (4) to inosine by adenosine deaminase (ADA) [EC 3.5.4.2], Interestingly, both 5 -nucleotidase and ADA activities were found to be highest in the leptomeninges of rat brain in contrast, the adenosine kinase activity was widely distributed throughout the brain parenchyma, which has negligible ADA activity... 

Ford JH, Evans J. 1985. Distribution of 5 -nucleotidase in the tissues of sheep and the effect of kidney and liver lesions on the activity of enzyme in plasma and urine. Res Vet Sci 39 103-109. 

Nucleotidase (5 -ribonucleotide phosphohydrolase, EC 3.1.3.5) is widely distributed in nature and a voluminous literature has appeared in the past decade on the enzyme from vertebrate tissues, seminal fluid, snake venoms, yeasts, and bacteria. Studies regarding the discovery and early investigations of the enzyme have been reviewed by Heppel (1) and... 

After purine nucleotides have been converted to the corresponding nucleosides by 5 -nucleotidases and by phosphatases, inosine and guanosine are readily cleaved to the nucleobase and ribose-1-phosphate by the widely distributed purine nucleoside phosphorylase. The corresponding deoxynucleosides yield deoxyribose- 1-phosphate and base with the phosphorylase from most sources. Adenosine and deoxyadenosine are not attacked by the phosphorylase of mammalian tissue, but much AMP is converted to IMP by an aminohydrolase (deaminase), which is very active in muscle and other tissues (fig. 23.20). An inherited deficiency of purine nucleoside phosphorylase is associated with a deficiency in the cellular type of immunity. 

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... 

Often there is no good clinical test available to determine the exact type of hepatic lesion, short of liver biopsy. There are certain patterns of enzyme elevation that have been identified and can be helpful (Table 38-3). ° The specificity of any serum enzyme depends on the distribution of that enzyme in the body. Alkaline phosphatase is found in the bile duct epithelium, bone, and intestinal and kidney cells. 5-Nucleotidase is more specific for hepatic disease than alkaline phosphatase, because most of the body s store of 5 -nucleotidase is in the liver. Glutamate dehydrogenase is a good indicator of centrolobular necrosis because it is found primarily in centrolobular mitochondria. Most hepatic cells have extremely high concentrations of transaminases. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are commonly measured. Because of their high concentrations and easy liberation from the hepato-cyte cytoplasm, AST and ALT are very sensitive indicators of necrotic lesions within the liver. After an acute hepatic lesion is established, it may take weeks for these concentrations to return to normal. ... 

The possibility that zonally distributed differenees in size and connections of the Purkinje cells are correlated with specific chemical properties of these cells was first raised by Marani (Marani and Voogd, 1977 Marani, 1981, 1982a Marani, 1986) on the basis of the distribution of 5 -nucleotidase and acetyleholinesterase in the molecular layer and by Chan-Palay (1984) who reported a restricted distribution of certain peptides in subsets of Purkinje cells. More recently a complete pattern of alternating zones of immunoreactive and non-immunoreactive Purkinje cells was described by Hawkes and Leclerc (1986, 1987) with a Purkinje cell-specific antibody (anti Zebrin-I) in the rat and by Brochu et al. (1990) with anti-Zebrin II in the rat and other species (see Section... 

The distribution of the Zebrin-positive Purkinje cells was very similar to the distribution of the enzyme 5 -nucleotidase in the molecular layer of certain rodents (Eisenman and Hawkes, 1989). 

The distribution of 5 -nucleotidase (5 -N) (Section 3.5.) in alternate longitudinal bands of high and low enzyme activity in the molecular layer of the cerebellar cortex of the mouse (Scott, 1963,1964,1965,1967) was the first evidence for the biochemical compart-mentalization of the cerebellar cortex. The pattern of 5 -N-positive and -negative zones is complete in the sense that it is present in all the lobules of vermis and hemisphere and unequivocal, because, in the mouse at least, the bands are clearly delineated (Marani, 1986). The 5 -N band pattern is very similar, if not identical, to the more recently described distribution of Purkinje cells in the rat, reacting with Purkinje cell-specific monoclonal antibodies to Zebrin-I (mabQl 13) (Eisenman and Hawkes, 1989). 

Fig. 131. Reconstructions of the zonal distribution of 5 -nucleotidase (5 -N) in the molecular layer of the cerebellum of the mouse. Numbers without prefix indicate the nomenclature for the 5 -N-positive bands of Marani (1982) P-numbers on the left side refer to the nomenclature for corresponding Zebrin I-positive bands of Hawkes and Leclerc (1987). ANT = anterior lobe FLO = flocculus PFL = paraflocculus II-X = lobules...

The epitopes recognized by Hawkes family of monoclonal antibodies known as the anti-Zebrins are localized on Purkinje cells (see Section 3.1.8.). Zonal patterns that are identical or very similar to Zebrin I and II have been described for the distribution of 5 -nucleotidase (see above), the p75 low affinity nerve growth factor receptor protein in the rat (Section 3.1.10., Fig. 38), protein kinase C delta (Fig. 133) (see Section 3.1.5.) and the B30 antibody of Stainier and Gilbert (1989) (see Section 3.1.8.). Immunoreactiv-ity in mouse Purkinje cells for an antibody against HNK is partially congruent with the Zebrin negative Purkinje cells, but Zebrin+/HNK-l- Purkinje cells also exist (Hawkes, 1992 Eisenman and Hawkes, 1993). The similarity between the Zebrin pattern and the transient zonal patterns in the development of the Purkinje cell specific marker L7 is discussed in Section 6.2. 

The numbering of 5 -nucleotidase-positive bands according to Marani (1986) and Hawkes and Leclerc s (1987) numbering system for the Zebrin-positive bands can be compared in Fig. 131 of the distribution of 5 -N in mouse cerebellum. 

A major drawback of many studies of the chemical neuroanatomy is that they were conducted in only one species, the rat. There is extensive evidence for species differences in the distribution of the synthetizing enzyme of acetylcholine (ChAT), muscarinic cholinergic receptors and acetylcholinesterase (see Section 3.10.), and there is reason to assume that a similar interspecies variability exists for other transmitter systems. The expression of Zebrin by certain subpopulations of Purkinje cells, and the zonal patterns in the distribution of 5 -nucleotidase, only occur in certain species. It is a fortunate coincidence for the experimental neuroscientist that the Zebrin zonal pattern is expressed in rats, but in other species like the cat or macaque monkeys all Purkinje cells are Zebrin-immunoreactive. Many species-differences in the chemical neuroanatomy of the cerebellum may be due to the selectivity of the antibodies employed in the im-munocytochemical techniques, but other differences may be real and may reflect true variations in structure or in the transmission and second messenger systems of the cerebellum. 

Eisenman EM, Hawkes R (1989) 5 -Nucleotidase and the MabQl 13 antigen share a common distribution in the cerebellar cortex of the mouse. Neuroscience, 31, 231-237. 

Fastbom J, Pazos A. Palacios JM (1987) The distribution of adenosine A1 receptors and 5 -nucleotidase in the brain of some commonly used experimental animals. Neuroscience, 22, 813-826. 

Marani E (1977) The subcellular distribution of 5 -nucleotidase activity in mouse cerebellum. Exp. Neurol, 57, 1042-1048. 

Phillips E, Newsholme EA (1979) Maximum activities, properties and distribution of 5 -nucleotidase, adenosine kinase and adenosine deaminase in rat and human brain. J. Neurochem., 33, 553-558. 

Figure 17 Facing page) Comparison of the subceUular distribution of HPMA copolymer-galactosamine (58) and cationic HPMA copolymers containing pendant side-chains terminating in oxyethy-trimethylammonium chloride (56), structure in panel (a). The profiles shown in panels (b) and (c) show rat liver fractionation using a percoll gradient at various times after iv administration of the conjugates. Panel (b) shows the distribution of I-labeled cationic HPMA copolymers at -e-10 min, -d- 20 min and -c- 60 min. Aiyl sul-fatase distribution (lysosomes) is shown in -f-. Panel (c) shows the distribution of I-labeled HPMA copolymer-galactosamine in this case, -g-10 min, -f- 20 min and -c- 60 min. Arylsulfatase distribution (lysosomes) is shown in -a- and 5 -nucleotidase (plasma membrane) in -C-.

The epidermis is an epithelium consisting of inner viable epidermis, a living hydrophilic layer, and outer nonviable epidermis, a hydrophobic layer made from dead cells. It is differentiated into stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale In the direction of dermis (Fig. 16.2). The viable epidermal layer has a thickness of about 0.02 to 0.2 mm. It is composed of many layers of keratinocytes, a widespread distribution of melanocytes, Langerhans cells, dendritic T cells, epidermotropic lymphocytes and Merkel cells, and a number of catabolic enzymes such as esterases, proteases, phosphatases, nucleotidases and lipases [Walters and Roberts, 2002 Barry, 2001). The outer and nonviable epidermis, namely, stratum corneum, is about 10 to 20 pm thick [Gregor and Ulrich, 2010). The stratum corneum Is deemed to be the major obstacle of drug permeation. 

The widely distributed and relatively nonspecific acid and alkaline phosphatases can convert nucleoside monophosphates to nucleosides, regardless of the base or of the position of the phosphate (2, 3, or 5 ). Rat liver lysosomes contain an acid nucleotidase which is not specific regarding the position of the phosphate, but which hydrolyzes adenine nucleotides faster than those of other bases (6) it is different from the nonspecific lysosomal sugar phosphatase. Some plants also contain a specific 3 -nucleotidase. 

Torrance, J. D., and Whittaker, D., 1979, Distribution of erythrocyte nucleotides in pyrimidine 5 -nucleotidase deficiency, Brit. J. Haematol., 43 423. 

Nucleotidases are phosphatases active against nucleotides, and such activity is widely distributed in nature. Among mammalian tissues one may mention alkaline intestinal phosphatase,acid prostatic phosphatase, and alkaline bone phosphatase. None of these preparations are specific for nucleotides, although extracts of prostate dephosphorylate nucleotides at a much faster rate than other esters. Enzymes which act only on nucleotides may occur in these tissues but their existence has not been proved. Several specific nucleotidases will now be discussed. 

The following three characteristic mammalian liver and kidney enzymes are absent from muscle catalase, xanthine oxidase, and D-amino oxidase. The distribution of many other enzymes in mammals is limited to particular organs. Thus arginase occurs only in the liver, alkaline phosphatase in the intestinal mucosa, acid phosphatase in kidney, spleen, and prostate, 5-nucleotidase in the testis, and a-mannosidase in the epididymis (see Table 4.6). The blood is disproportionately rich in carbonic anhydrase, and the pancreas in ribonuclease. Glutamine synthetase, which condenses... 

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