Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.4.37 (CNPase)
 539 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Myelin purified from the central nervous system of Xenopus laevis contained the same major lipid and protein components as human myelin. However, some minor differences in the myelin proteins were noted. The Xenopus basic protein had a higher apparent mol wt. on sodium dodecyl sulfate gels than the corresponding mammalian protein. The absolute specific activity of 2',3'-cyclic nucleotide 3'-phosphohydrolase in the Xenopus myelin was considerably higher than in mammals. There were differences in the high mol wt. proteins, and the glycoproteins in Xenopus myelin were more heterogeneous than those in mammals. Peripheral myelin from Xenopus sciatic nerve was compared with that from the rat. The lipids in the two types of myelin were similar. There was a major glycoprotein in the Xenopus myelin corresponding to the P0 protein and a basic protein of slightly larger mol wt. than the P1 protein of rat myelin.
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PMID:A biochemical comparison of Xenopus laevis and mammalian myelin from the central and peripheral nervous systems. 21 Dec 3

In this report, we describe the fractionation of crude axolemmal fractions from rat lower brainstem into subfractions enriched in markers for either periaxolemmal myelin or axolemma. These subfractions were isolated on density gradients as bands layering on 0.8M and 1.0M sucrose. Both subfractions consisted of unilamellar vesicles. Relative to myelin purified from the same starting material, the 0.8M subfraction was enriched in MAG, CNPase, carbonic anhydrase and Na+, K+ ATPase but was extremely low in PLP and MBP. In addition, this fraction exhibited a protein profile distinct from myelin. The 1.0M fraction was also highly enriched in Na+, K+ ATPase and had an overall composition similar to the 0.8M subfraction. However, it differed from the 0.8M subfraction by being low in MAG, CNPase, and carbonic anhydrase, but enriched in voltage-dependent Na+ channel, axon-specific fodrin, and MAP-1B. Based on these characteristics we concluded that the 0.8M and 1.0M subfractions were highly enriched in periaxolemmal myelin and axolemmal membrane, respectively. Plasmolipin10 was unique with equally high levels in myelin and in the 0.8M and 1.0M subfractions. Both subfractions were enriched, relative to myelin, in the alpha subunit of the GTP binding protein, Go, and the alpha subunit common to all G proteins, GA/1. Electrophysiology with membrane subfractions fused to lipid bilayers showed that both membranes contained sets of K+ and Cl- channels, which based on channel sizes and open times, are largely distinct from one another.
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PMID:Isolation and characterization of periaxolemmal and axolemmal enriched membrane fractions from the rat central nervous system. 138 38

The neurochemical effects of maternally administered cadmium (50 ppm through drinking water from 0 day of pregnancy) on the whole brain of offsprings exposed during gestation were studied in 7, 14 and 21 days old rats. The developmental pattern of body weight, protein, DNA and RNA contents in brain were not affected in Cd exposed pups of any age group. Brain weights were significantly reduced in exposed pups of postnatal age of 7 and 14 days but were comparable to controls in 21 days old pups. The content of Cd increased significantly in the brain of gestationally exposed pups of 7 days and remained almost stationary throughout the experimental period. The activity of Acetylcholinesterase, Na+, K(+)-ATPase, CNPase, 5'-Nucleotidase in the brain increased significantly from 7 to 21 days of age in control animals. In experimental pups, the activity of most of the enzymes was almost comparable to controls at 7 days of age except succinate dehydrogenase, which was significantly inhibited at 7, 14 and 21 days compared to controls. The activity of other enzymes was also significantly inhibited in the brain of experimental pups compared to controls of 21 days of age indicating marked retardation in the development of these enzymes. However, these changes had no correlation with the accumulation of Cd in the brain. These studies indicate that in utero exposure to Cd may retard the development of certain neurochemicals which may have long term implications on the brain functions.
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PMID:Gestational cadmium exposure and brain development: a biochemical study. 188 99

In the presence of H2O2, solutions of Fe2+ were applied to brain homogenate and isolated myelin from adult SWV control mice and the shiverer dysmyelinating mutant mouse as a source of a reactive oxygen species (Fenton reaction). Under these conditions, lipid peroxidation was initiated and measured as thiobarbituric acid-reactive oxidation products (TBAR). This was accompanied by 85% inhibition of myelin-associated Na+,K(+)-ATPase and 25% inhibition of 5'-nucleotidase. In contrast, CNPase activity was not altered. Studies on the shiverer mutant brain revealed that in spite of hypomyelination and prevalence of premature, myelin-like membranes in the homogenate, the myelin-related enzymes reacted as normal enzymes to peroxidation. Differences in the resistance of Na+,K(+)-ATPase to peroxidation in the brain homogenate and myelin suggest that the myelin enzyme is extremely sensitive to reactive oxygen toxicity.
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PMID:Effect of lipid peroxidation on Na+,K(+)-ATPase, 5'-nucleotidase and CNPase in mouse brain myelin. 216 9

The in vitro effect of methylmercury (MM) on the enzymatic activities of brain cell specific marker enzymes, choline acetyltransferase (CAT), glutamic acid decarboxylase (GAD), 2',3'-cyclic nucleotide phosphohydrolase (CNP), glutamine synthetase (GS) and enolase was examined. The results demonstrate that at 100 microM MM, GS activity was not affected whereas a small decrease in the activity of both GAD (20%) and enolase (10%) was observed. CNP and CAT activity appeared to be more sensitive toward MM with 100 microM MM producing inhibition of 50% and 30%, respectively. The addition of sulfhydryl protecting reagents such as DTT or sodium thioglycolate can restore the enzyme activities to normal control levels despite prior exposure of the enzymes to MM.
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PMID:Studies of the in vitro effect of methylmercury chloride on rat brain neurotransmitter enzymes. 288 7

Oligodendrocytes generate myelin as extensions of the plasma membrane. Myelin has been well characterized, yet little is known concerning oligodendrocyte plasma membrane. We have developed a reproducible method for the isolation of an oligodendrocyte plasma membrane-rich fraction (F2.2). F2.2 has a 25-fold enrichment in K+-dependent p-nitrophenyl phosphatase, a plasma membrane marker. Impurities are composed of Golgi elements (8-12%), microsomes (4-6%), and lysosomal membranes (1-5%). Our starting material was oligodendrocytes kept in culture in a nonattached state for 3 to 5 d. After disrupting the cells and removing nuclei (P1), the supernatant (SP1) was fractionated on a self-generating 20% Percoll gradient into three bands: F1, F2, and F3. F1 had only 3% of the applied protein and was not characterized. F2, with 11% of the protein, was fivefold enriched in plasma membrane. F3 had 27% of initial protein; it consisted of a crude mitochondrial and lysosomal fraction. F2 was further purified by first washing it hypotonically, treating it with Mg2+, and then fractionating it on a Ficoll step gradient that yielded F2.2 at the interphase. Morphologically F2.2 comprises 1) membranous sheets, often with more than one membrane in close apposition; 2) membrane vesicles of various sizes and shapes frequently filled with amorphous material; 3) Golgi elements; and 4) unrecognizable profiles. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis protein profile of F2.2 reveals CNPase as a major component in agreement with the high CNPase specific activity (3,860 mumol/mgP/h) found in F2.2. Other significant polypeptides have Mr = 170,000, 135,000, 108,000, 80,000, 53,000, 38,500, 32,000, and 22,200.
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PMID:Plasma membrane of cultured oligodendrocytes: I. Isolation, purification, and initial characterization. 297 38

A rat brain P3 fraction enriched in ER derived microsomes was centrifuged through a 20-40% linear sucrose gradient in a Beckman Ti-14 Zonal rotor and 11 fractions were obtained. The distribution of marker enzyme activities and protein were determined in these 11 subfractions. NADPH-Cytochrome C reductase, choline phosphotransferase were employed for endoplasmic reticulum, Na+,K+-ATPase, 5'-nucleotidase, and acetylcholinesterase were employed for plasma membrane, 2',3'-cyclic nucleotide phosphohydrolase was employed for myelin. The bulk of the protein was recovered in the 24-34% sucrose fractions, Na+,K+-ATPase, 5'-nucleotidase, and acetylcholinesterase were in the 22-38% sucrose fractions while NADPH-cytochrome C reductase and CNPase were enriched in the 20-22% sucrose fractions. The ethanolamine and the serine base exchange activities had a bimodal distribution, with highest specific activities in sucrose fractions 32-34% and 20-24%. Choline base exchange activity was nearly undetectable in all the fractions. The specific activities of CDP-choline phosphotransferase, and phospholipid-N-methyltransferase were highest in the 20-22% sucrose fraction. Phospholipid-N-methyltransferase activity was significantly stimulated in the presence of exogenous phospholipid acceptors as phosphatidylethanolamine or phosphatidylmonomethylethanolamine or phosphatidyldimethylethanolamine, however, the greatest response was with phosphatidylmonomethylethanolamine. The rat brain P3 fraction yielded a population of a membrane at the light end of the sucrose gradient which has a buoyant density similar to myelin but seemed to be enriched with NADPH cytochrome C reductase and phospholipid modifying enzymes. This is in contrast to liver microsomes submitted to a similar fractionation.
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PMID:Distribution of selected phospholipid modifying enzymes in rat brain microsomal subfractions prepared by density gradient zonal rotor centrifugation. 298 22

Monoclonal antibody against 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP) was generated by fusing mouse myeloma cells with spleen cells from BALB/c mice immunized with delipidated white matter from rat corpus callosum. The antibody was characterized by solid-phase radioimmunoassay, immunoblot of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), immunoprecipitation from C6 glioma cells, and indirect immunofluorescence staining of monolayer cultures containing oligodendrocytes. The monoclonal antibody bound specifically to an intracellular antigen of oligodendrocytes, but not to Schwann cells, astrocytes, neurons, or fibroblast cytoplasm. The immunoblot of SDS-PAGE of CNS myelin showed that the antibody identified two protein bands at 48,000 and 50,000 molecular weight. These proteins were not identified in peripheral nervous system myelin. The monoclonal antibody immunoprecipitated CNP enzyme activity from extracts of C6 glioma cells. This monoclonal antibody should prove useful in further study of this myelin-specific enzyme in CNS myelin and in cells responsible for myelin production.
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PMID:A monoclonal antibody raised to corpus callosum extract reacts with 2',3'-cyclic nucleotide 3'-phosphohydrolase. 299 39

The relation of the polar head group composition of cellular phospholipids to a biochemical expression of oligodendroglial differentiation was studied in cultured C-6 glial cells. Induction of the oligodendroglial enzyme, 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP), was determined after alteration of the polar head group composition of phospholipids by exposure of the cells to choline analogues, especially N,N'-dimethylethanolamine. To accomplish the phospholipid alteration, cells were grown in the presence of the analogue in medium free of exogenous lipid, i.e., first for 24 h in 10% delipidated serum and then for 48 h in serum-free medium. The 48-h exposure to serum-free medium resulted in untreated C-6 cells in a several fold increase in CNP activity, but in cells treated with 2.5 mM N,N'-dimethylethanolamine, total inhibition of this induction was observed. A graded, concentration-dependent inhibitory effect of the analogue on the induction of CNP was defined. The effect of the analogue was relatively specific, e.g., the activity of another plasma membrane enzyme of C-6 cells, (Na+ + K+)-activated ATPase, was not affected. Morever, there was no evidence of a toxic effect of the analogue; thus, total protein synthesis and cell growth were not altered, and the induction of CNP in serum-free medium recurred after removal of the analogue. N,N'-Dimethylethanolamine was shown to be incorporated into cellular phospholipids, primarily at the expense of phosphatidylcholine. The data define an important role for the polar head group composition of membrane phospholipids in oligodendroglial differentiation in this model system.
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PMID:Relation of cellular phospholipid composition to oligodendroglial differentiation in C-6 glial cells. 300 Dec 26

Biochemical and morphological studies of myelin subfractions were undertaken on Lewis rats during the early stage of the development of experimental allergic encephalomyelitis (EAE). Myelin subfractions, obtained by sucrose density gradient centrifugation at 10 days post-induction, were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and assayed for 2':3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) activity. Aliquots were processed for electron microscopic analysis. When comparing the myelin subfractions of EAE-affected animals with those of controls, differences were observed only in the light fractions, i.e., a decrease in the specific activity of CNPase and in the percentage of basic proteins relative to the total proteins of the fraction. This decrease was also evident in the basic protein/proteolipid protein ratio which is frequently used in the literature. In addition, electron microscopic observations demonstrated strong differences in the morphology of the same fraction. These findings suggest that the light fraction is the most sensitive in the early stages of the disease and must play a key role in demyelinating processes.
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PMID:Biochemical changes in central nervous system membranes in experimental allergic encephalomyelitis. 301 92


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