Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.27.4 (ribonuclease)
6,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Expression of aquaporin-8 mRNA has previously been shown in hepatocytes, pancreatic acinar cells, colon epithelial cells and seminiferous tubules of the testis in the rat by in situ hybridization technique. However, immunolocalization of this water channel has not yet been demonstrated. In the present study, the localization of immunoreactive aquaporin-8 and expression of the mRNA were examined in rat organs (cerebrum, cerebellum, eye, salivary gland, heart, lung, liver, pancreas, esophagus, stomach, jejunum, ileum, colon, testis, ovary, kidney, spleen and lymphnode) by immunohistochemistry using an antibody against aquaporin-8 and ribonuclease protection assay. Aquaporin-8 was distinctly immunolocalized on the apical membranes of pancreatic acinar cells and mucosal epithelium of the colon and jejunum. In the liver, the bile canalicular membrane of hepatocytes was immunostained. In the testis, immunoreactive aquaporin-8 was demonstrated on the luminal side of the seminiferous tubules. At high magnification, the peroxidase reaction products appeared on the ramified cytoplasmic membrane of Sertoli cells surrounding the residual bodies or spermatogenic cells. Specificity of the antibody was verified by Western blot analysis showing a minor approximately 28 kDa band (deduced deglycosylated form of aquaporin-8) and a major approximately 30 kDa band (glycosylated form) in these organs. The intensity of aquaporin-8 immunoreactivity was approximately comparable to that of aquaporin-8 mRNA expression in the liver, pancreas, colon, jejunum and testis. The aquaporin-8 mRNA expression in the hepatocytes was presumed to be closely associated with the structure of bile canaliculi since the message was detected in hepatocytes immediately after isolation from the liver but not in cells following cultivation for three days. The localization of immunoreactive aquaporin-8 indicated functions for this water channel in the secretion of bile and pancreatic juice, and the secretion or absorption of water in the colon and jejunum, and the maturation or liberation of spermatogenic cells in the testis.
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PMID:Immunolocalization of aquaporin-8 in rat digestive organs and testis. 1143 86

Eosinophils were separated from other types of cells in horse blood or rat peritoneal fluid by centrifugation in concentrated albumin solutions. Eosinophils did not appear to be damaged by this separation procedure. A technique was also devised for isolation of cytoplasmic granules from eosinophils, thus allowing studies on enzyme content of the granules. Granules from both horse and rat eosinophils contained a number of hydrolytic enzymes, similar in variety and in concentration to those previously found in granules of rabbit polymorphonuclear leucocytes. Eosinophil granules differed from those of the rabbit granulocyte in their high content of peroxidase and the absence of lysozyme and phagocytin. On disruption of eosinophil granules by repeated freezing and thawing in saline, cathepsin, ribonuclease, arylsulfatase and beta glucuronidase were released into solution, but phosphatases were partially and peroxidase completely bound to the insoluble granule residue. Peroxidase could be extracted from the granule residue with weak acid. Eosinophil granules thus are lysosome-like structures.
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PMID:ISOLATION OF GRANULES FROM EOSINOPHIL LEUCOCYTES AND STUDY OF THEIR ENZYME CONTENT. 1407 91

Vacuoles were isolated from suspension cultures of sugarcane (Saccharum sp.) cells by centrifugation of protoplasts at high g force against a 12% (w/v) Ficoll solution. Distribution of marker enzymes and Concanavalin A binding showed an 11% contamination of the vacuole preparation by cytoplasmic components, mitochondria, and endoplasmic reticulum, and 18% contamination by plasma membrane. Acid phosphatase, carboxypeptidase, protease, peroxidase, and ribonuclease activities were enriched in isolated vacuoles. Carboxypeptidase was tonoplast-bound, whereas the other enzymes were soluble. Sucrose, reducing sugars, and free amino acids were measured in protoplasts and vacuoles during growth of cells in suspension culture. Sucrose and reducing sugar content of vacuoles increased as the culture aged, while free amino acids decreased sharply.
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PMID:Vacuoles from Sugarcane Suspension Cultures : I. ISOLATION AND PARTIAL CHARACTERIZATION. 1666 93

To elucidate the deleterious effects of excess lead on radish (Raphanus sativus) cv. Jaunpuri plants were grown in refined sand in complete nutrient solution for 30 days. On the 31st day lead nitrate was superimposed at 0.1 and 0.5mM to radish for 65 days. A set of plants in complete nutrient solution was maintained as control for the same period without lead. Excess Pb at 0.5mM showed growth depression with interveinal chlorosis on young leaves at apex. Excess Pb reduced the fresh and dry weight pronouncedly at d 65. Lead accumulation reduced the concentration of chlorophyll, iron, sulphur (in tops), Hill reaction activity and catalase activity whereas increased the concentration of phosphorus, sulphur (in roots) and activity of peroxidase, acid phosphatase and ribonuclease in leaves of radish.
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PMID:Excess lead alters growth, metabolism and translocation of certain nutrients in radish. 1792 49

Despite the therapeutic potential of tempol (4-hydroxy-2,2,6,6-tetra-methyl-1-piperidinyloxy) and related nitroxides as antioxidants, their effects on peroxidase-mediated protein tyrosine nitration remain unexplored. This posttranslational protein modification is a biomarker of nitric oxide-derived oxidants, and, relevantly, it parallels tissue injury in animal models of inflammation and is attenuated by tempol treatment. Here, we examine tempol effects on ribonuclease (RNase) nitration mediated by myeloperoxidase (MPO), a mammalian enzyme that plays a central role in various inflammatory processes. Some experiments were also performed with horseradish peroxidase (HRP). We show that tempol efficiently inhibits peroxidase-mediated RNase nitration. For instance, 10 muM tempol was able to inhibit by 90% the yield of 290 muM 3-nitrotyrosine produced from 370 muM RNase. The effect of tempol was not completely catalytic because part of it was consumed by recombination with RNase-tyrosyl radicals. The second-order rate constant of the reaction of tempol with MPO compound I and II were determined by stopped-flow kinetics as 3.3 x 10(6) and 2.6 x 10(4) M(-1) s(-1), respectively (pH 7.4, 25 degrees C); the corresponding HRP constants were orders of magnitude smaller. Time-dependent hydrogen peroxide and nitrite consumption and oxygen production in the incubations were quantified experimentally and modeled by kinetic simulations. The results indicate that tempol inhibits peroxidase-mediated RNase nitration mainly because of its reaction with nitrogen dioxide to produce the oxammonium cation, which, in turn, recycles back to tempol by reacting with hydrogen peroxide and superoxide radical to produce oxygen and regenerate nitrite. The implications for nitroxide antioxidant mechanisms are discussed.
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PMID:Inhibition of myeloperoxidase-mediated protein nitration by tempol: Kinetics, mechanism, and implications. 1849 4

Structural characterization of a glycopeptide is not easily attained through collision-induced dissociation (CID), due to the extensive fragmentation of glycan moieties and minimal fragmentation of peptide backbones. In this study, we have exploited the potential of electron-transfer dissociation (ETD) as a complementary approach for peptide fragmentation. Model glycoproteins, including ribonuclease B, fetuin, horseradish peroxidase, and haptoglobin, were used here. In ETD, radical anions transfer an electron to the peptide backbone and induce cleavage of the N-Calpha bond. The glycan moiety is retained on the peptide backbone, being largely unaffected by the ETD process. Accordingly, ETD allows not only the identification of the amino acid sequence of a glycopeptide, but also the unambiguous assignment of its glycosylation site. When data acquired from both fragmentation techniques are combined, it is possible to characterize comprehensively the entire glycopeptide. This is being achieved with a mass spectrometer capable of alternating between CID and ETD on-the-fly during an LC/MS/MS analysis. This is demonstrated here with several tryptic glycopeptides.
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PMID:Characterization of glycopeptides by combining collision-induced dissociation and electron-transfer dissociation mass spectrometry data. 1906 42

A simple, sensitive, and rapid quantitative LC-MS/MS assay was designed for the simultaneous quantification of free and glycoprotein bound monosaccharides using a multiple reaction monitoring (MRM) approach. This study represents the first example of using LC-MS/MS methods to simultaneously quantify all common glycoprotein monosaccharides, including neutral and acidic monosaccharides. Sialic acids and reduced forms of neutral monosaccharides are efficiently separated using a porous graphitized carbon column. Neutral monosaccharide molecules are detected as their alditol acetate anion adducts [M + CH(3)CO(2)](-) using electrospray ionization in negative ion MRM mode, while sialic acids are detected as deprotonated ions [M - H](-). The new method exhibits very high sensitivity to carbohydrates with limits of detection as low as 1 pg for glucose, galactose, and mannose, and below 10 pg for other monosaccharides. The linearity of the described approach spans over three orders of magnitudes (pg to ng). The method effectively quantified monosaccharides originating from as little as 1 microg of fetuin, ribonuclease B, peroxidase, and alpha(1)-acid glycoprotein human (AGP) with results consistent with literature values and with independent CE-LIF measurements. The method is robust, rapid, and highly sensitive. It does not require derivatization or postcolumn addition of reagents.
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PMID:Multiple-reaction monitoring liquid chromatography mass spectrometry for monosaccharide compositional analysis of glycoproteins. 1931 80

Due to widespread industrial use, chromium (Cr) is considered a hazardous environmental pollutant. It is known to inhibit plant growth and development. The present study provides the evidence of the phytotoxicity of this metal on the pea (Pisum sativum L. cv Azad) plants. The plants of pea (Pisum sativum L.) were grown in refined sand under different concentrations i.e. 0.05, 0.1, 0.2, 0.3 and 0.4 mM of Cr (VI) in order to study the effect on growth and yield, photosynthetic pigments, relative water content, non-reducing sugar and protein with activity of certain enzymes like catalase, peroxidase, starch phosphorylase and ribonuclease. The analysis of the results showed that photosynthetic pigments (68.68%), relative water contents (62.77%), non-reducing sugar (66.66%) and protein (81.57%) were decrease along with reduction in plant height (52.69%) and leaf area (50.81%) of the pea plants. However, in response to various concentration of Cr exposed plants showed significant induction of reducing and total sugars with enzymes like catalase, starch phosphorylase and ribonuclease. The translocation of Cr in various part of pea plant have been found in order of root> stem> leaves>seeds which ranged between 34.8 to 217.3 mg g(-1) d.wt. (dry weight) in roots, 6.5 to 173.13 mg g(-1) d.wt. in shoot, 4.2 to 74.43 mg g(-1) d.wt. in leaves and 0.94 to 8.64 mg g(-1) d.wt. in seeds, that is also reflected by the transfer factor of Cr from refined sand to tested species.
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PMID:Chromium (VI) induced phytotoxicity and oxidative stress in pea (Pisum sativum L.): biochemical changes and translocation of essential nutrients. 2012 Apr 64

Free radicals generated during peroxidase-catalyzed oxidation of two xenobiotics, carcinogenic Sudan I and an anticancer agent ellipticine, easily attack unmodified proteins but not glycoproteins. A significant inverse correlation between the extent of glycosylation of proteins and the degree of binding of Sudan I or ellipticine radicals to these proteins was observed, whereby the protection only occurs if oligosaccharides are covalently bound to the proteins. No influence of any other variables was found and further confirmed by experiments with proteins containing identical polypeptide chains differing only by the absence (ribonuclease A) or the presence (ribonuclease B) of a single oligosaccharide. The free radicals that are subject of this study did not react with the oligosaccharides because higher levels of the corresponding dimers, reaction products of the radicals, were found in presence of highly glycosylated proteins. The results indicate that carbohydrates protect polypeptides against modification by free radicals derived from toxic xenobiotics and provide passive shielding of the protein moiety.
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PMID:Glycosylation protects proteins against free radicals generated from toxic xenobiotics. 2061 8

We have developed a novel system for coupling reverse-phase (RP) and hydrophilic interaction liquid chromatography (HILIC) online in a micro-flow scheme. In this approach, the inherent solvent incompatibility between RP and HILIC is overcome through the use of constant-pressure online solvent mixing, which allows our system to perform efficient separations of both hydrophilic and hydrophobic compounds for mass spectrometry-based proteomics applications. When analyzing the tryptic digests of bovine serum albumin, ribonuclease B, and horseradish peroxidase, we observed near-identical coverage of peptides and glycopeptides when using online RP-HILIC--with only a single sample injection event--as we did from two separate RP and HILIC analyses. The coupled system was also capable of concurrently characterizing the peptide and glycan portions of deglycosylated glycoproteins from one injection event, as confirmed, for example, through our detection of 23 novel glycans from turkey ovalbumin. Finally, we validated the applicability of using RP-HILIC for the analysis of highly complex biological samples (mouse chondrocyte lysate, deglycosylated human serum). The enhanced coverage and efficiency of online RP-HILIC makes it a viable technique for the comprehensive separation of components displaying dramatically different hydrophobicities, such as peptides, glycopeptides, and glycans.
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PMID:Online coupling of reverse-phase and hydrophilic interaction liquid chromatography for protein and glycoprotein characterization. 2063 60


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