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Reid P, Culling CFA. The Periodate Oxidation of Carbohydrates in Relation to the PAS Reaction. J Histotechnol 2013. [DOI: 10.1179/his.1980.3.3.82] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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Clamp JR, Creeth JM. Some non-mucin components of mucus and their possible biological roles. CIBA FOUNDATION SYMPOSIUM 2008; 109:121-36. [PMID: 6394241 DOI: 10.1002/9780470720905.ch9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Non-mucin components have essential roles in the protective functions of mucous secretions. Secretory IgA (SIgA) antibodies probably act by blocking the attachment of pathogenic microorganisms to mucosal cells. In addition SIgA1 may render bacteria more 'mucophilic', possibly by virtue of the 'mucus-like' stretch that the immunoglobulin molecule possesses. Lysozyme will attack cell walls of susceptible bacteria. As the enzyme associates strongly with mucus glycoproteins the mucus layer is provided with powerful bactericidal properties. Lactoferrin, normally unsaturated, sequesters any free iron in secretions, so exerting a bacteriostatic action on iron-requiring microorganisms. In addition it may protect mucus glycoproteins from iron-catalysed active oxygen species. This mucoprotective action would be overcome during infections. Attention is also directed towards a possible copper-mediated limited degradation by hydrogen peroxide. Surfactants and free lipid have long been recognized as components of normal bronchial mucus. For example, some lipid is tightly but non-covalently bound to a hydrophobic region of bronchial mucin. More intriguing is the presence of small amounts of covalently bound lipid in normal human gastric mucin. In addition, normal human gastric mucus contains significant amounts of a galactose-rich polysaccharide. The function of this is not known but it may act as a cross-linking strand in the mucus gel structure or as a renewable cell membrane component, perhaps interacting between glycocalyx and the mucus layer.
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Durant JA, Corrier DE, Stanker LH, Ricke SC. Expression of the hilA Salmonella typhimurium gene in a poultry Salm. enteritidis isolate in response to lactate and nutrients. J Appl Microbiol 2000; 89:63-9. [PMID: 10945780 DOI: 10.1046/j.1365-2672.2000.01089.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Pathogens express virulence genes in response to the combination of environmental conditions present in the host environment. The crop is the first gastrointestinal environment encountered in birds. However, feed withdrawal alters the crop environment resulting in an increased pH, and decreased concentrations of lactate, glucose and amino acids compared with unmoulted birds. Salmonella enteritidis infections increase significantly in hens that have been force moulted by feed withdrawal. The present study examined the effects of pH, carbohydrate sources, amino acids and lactate on expression of Salm. enteritidis virulence by measuring expression of hilA. The hilA gene encodes a transcriptional activator that regulates expression of Salmonella virulence genes in response to environmental stimuli. HilA expression was determined using a poultry isolate of Salm. enteritidis carrying a hilA-lacZY transcriptional fusion from Salm. typhimurium. The media used were Luria Bertani (LB) broth and LB broth diluted 1:5 (DLB). The expression of hilA was 2.9-fold higher in DLB broth compared with LB broth which suggested that there is a nutritional component to the regulation of hilA. Addition of 0.2% glucose, fructose or mannose to LB and DLB reduced hilA expression 1.5 to twofold. Addition of 0.2% Casaminoacids, arabinose, fucose, or lactose had little effect on hilA expression. Lactate (25 and 50 mmmol 1-1) reduced hilA expression at pH 6, 5 and 4, with the lowest expression occurring at pH 4. Based on these results it appears that the composition of the crop lumen could potentially influence Salm. enteritidis virulence expression.
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Affiliation(s)
- J A Durant
- Department of Poultry Science, Texas A and M University, College Station 77843-2472, USA
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Gum J, Hicks J, Lagace R, Byrd J, Toribara N, Siddiki B, Fearney F, Lamport D, Kim Y. Molecular cloning of rat intestinal mucin. Lack of conservation between mammalian species. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54629-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Reid PE, Park CM. Carbohydrate histochemistry of epithelial glycoproteins. PROGRESS IN HISTOCHEMISTRY AND CYTOCHEMISTRY 1990; 21:1-170. [PMID: 2267321 DOI: 10.1016/s0079-6336(11)80069-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- P E Reid
- Department of Pathology, Faculty of Medicine, University of British Columbia, Vancouver, Canada
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Abstract
The affinity of pig gastric mucus glycoprotein for counter ions of various valencies was examined. Ions of higher valency were bound with increasing avidity, but the degree of binding was apparently not influenced by the ionic radius. The affinity of the glycoprotein for the ions studied may be ranked: Fe3+ greater than Al3+ greater than Ca2+ greater than Cs+ congruent to Na+. The binding of calcium was inhibited by high ionic strength and was sensitive to the pH of the environment. Enzymatic removal of sialic acid slightly reduced the calcium binding capacity.
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Shub MD, Pang KY, Swann DA, Walker WA. Age-related changes in chemical composition and physical properties of mucus glycoproteins from rat small intestine. Biochem J 1983; 215:405-11. [PMID: 6651768 PMCID: PMC1152409 DOI: 10.1042/bj2150405] [Citation(s) in RCA: 78] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Mucus glycoproteins from newborn and adult rat small intestine were radiolabelled in vivo with Na2 35SO4 and isolated from mucosal homogenates by using Sepharose 4B column chromatography followed by CsCl-density-gradient centrifugation. Non-covalently bound proteins, lipids and nucleic acids were not detected in the purified glycoproteins. Amino acid, carbohydrate and sulphate compositions were similar to chemical compositions reported for other intestinal mucus glycoproteins, as were sedimentation properties. There were, however, important differences in the chemical and physical characteristics of the mucus glycoproteins from newborn and adult animals. The buoyant density in CsCl was higher for the glycoproteins from newborn rats (1.55 g/ml versus 1.47 g/ml). On sodium dodecyl sulphate/polyacrylamide/agarose-gel electrophoresis, the glycoprotein from newborn rats had a greater mobility than the adult-rat sample. Although both preparations had similar general amino acid compositions, variations were observed for individual amino acids. The total protein content was greater in the glycoprotein from newborn animals (27%, w/w, versus 18%, w/w). The molar ratio of carbohydrate to protein was less in the newborn, primarily owing to a decreased fucose and N-acetylgalactosamine content. Comparison of the molar ratio of fucose and sialic acid to galactose for both glycoproteins demonstrated a reciprocal relationship similar to that described by Dische [(1963) Ann. N.Y. Acad. Sci. 106, 259-270]. The sulphate content was greater in the glycoprotein from newborn rats (5.5%, w/w, versus 0.9%, w/w). Both had similar sedimentation coefficients in a dissociative solvent. These results suggest an age-related difference in the types of mucus glycoproteins synthesized by small intestine.
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Witas H, Sarosiek J, Aono M, Murty VL, Slomiany A, Slomiany BL. Lipids associated with rat small-intestinal mucus glycoprotein. Carbohydr Res 1983; 120:67-76. [PMID: 6627254 DOI: 10.1016/0008-6215(83)88007-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The lipid content and composition of rat small-intestinal mucus, and the purified mucus glycoprotein before and after Pronase digestion were investigated. The mucus, obtained by the instillation of intestine with 2M NaCl, was fractionated on Bio-Gel A-50 in the presence of 6M urea and the mucus glycoprotein free of noncovalently bound protein was isolated. A portion of the purified glycoprotein was subjected to Pronase digestion to yield glycopeptides. The native mucus, and the purified glycoprotein and glycopeptides were extracted with chloroform-methanol, and the lipids contained in the extracts were analyzed. The lipids accounted for 17.6 of the dry weight of mucus, 26.4 of the mucus glycoprotein, and 25.3% of the glycopeptides. In comparison to mucus, the lipids associated with mucus glycoprotein contained 1.9 times more phospholipids and 2.1 times more glycolipids, showed a 26% increase in neutral lipids, and were virtually free of glycosphingolipids. Treatment of the purified glycoprotein with Pronase led to a moderate (22.3%) loss in neutral lipids, 4.3-fold decrease in phospholipids, and 52.3% increase in glyceroglucolipids. The results indicate that while the interaction of mucus glycoprotein with phospholipids involves its Pronase-susceptible region, the interaction with glyceroglucolipids occurs in the glycosylated region of the glycoprotein that is resistant to proteolysis.
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11
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Parsons CM, Potter LM, Brown RD. Effects of dietary carbohydrate and of intestinal microflora on excretion of endogenous amino acids by poultry. Poult Sci 1983; 62:483-9. [PMID: 6302653 DOI: 10.3382/ps.0620483] [Citation(s) in RCA: 64] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The effects of dietary carbohydrate and of intestinal microflora on excretion of endogenous amino acids by poultry were investigated. Excretion of endogenous amino acids was compared among fasted roosters, intact roosters fed low- or high-fiber, N-free diets, and surgically-modified (SM) roosters fed a low-fiber, N-free diet. The low-fiber diet contained 50% corn starch, 45% glucose, and 5% cellulose, whereas the high-fiber diet contained 25% each of corn starch, glucose, and raw potato starch, 17.5% cellulose, and 7.5% pectin. Digesta were obtained from the terminal ileum of SM roosters to eliminate effects of the microflora in the large intestine and ceca. The roosters were force-fed 60 g of the appropriate diet (30 g at the initiation of the trial followed by an additional 30 g 6 hours later). Excreta or digesta and urine were collected quantitatively for 48 hr after the first force-feeding. Roosters fed the high-fiber diet excreted substantially more (P less than .05) amino acids than did fasted roosters or roosters fed a low-fiber diet. Excreta from roosters fed the high-fiber diet contained higher (P less than .05) levels of alanine and aspartic acid than excreta from fasted or digesta from SM roosters, indicating substantial microbial synthesis of amino acids in the gut. In contrast, amino acid composition of excreta from fasted and intact roosters fed the low-fiber diet was similar to that of digesta from SM roosters, suggesting less microbial influence. Excretion of glucosamine plus galactosamine by SM roosters was approximately twice that of intact roosters fed the same diet. Glycine was the most abundant amino acid in digesta of SM roosters. Results of this study indicate that dietary carbohydrate substantially affects excretion of endogenous amino acids by poultry and that fasted birds may not provide an accurate estimate of endogenous amino acid excretion for birds fed high-fiber feedstuffs in amino acid digestibility trials.
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Smits HL, van Kerkhof PJ, Kramer MF. Isolation and partial characterization of rat duodenal-gland (Brunner's-gland) mucus glycoprotein. Biochem J 1982; 203:779-85. [PMID: 7115315 PMCID: PMC1158296 DOI: 10.1042/bj2030779] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
A mucus glycoprotein was isolated from the duodenal glands of the rat and purified by repeated density-gradient centrifugation. The characterized glycoprotein is unique to the mucous cells of the duodenal glands and is not present in parts of the small intestine devoid of these glands. The chemical composition of the purified glycoprotein is characteristic for glycoproteins of the mucin-type. Its protein content is relatively high and amount to 35% by weight. No neuraminic acid and little sulphate (2%) is present. Evidence is presented that the native glycoprotein is built up from subunits held together via disulphide bridges in a non-glycosylated region of the protein core.
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Liau YH, Horowitz MI. Incorporation in vitro of [3H]glucosamine or [3H]glucose and [35S]SO42- into rat gastric mucosa. Presence of N-acetylhexosamine mono- and disulfates and galactose monosulfate in glycoprotein. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(18)34583-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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PARSONS C, POTTER L, BROWN R, WILKINS T, BLISS B. Microbial Contribution to Dry Matter and Amino Acid Content of Poultry Excreta. Poult Sci 1982. [DOI: 10.3382/ps.0610925] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Mantle M, Allen A. Isolation and characterization of the native glycoprotein from pig small-intestinal mucus. Biochem J 1981; 195:267-75. [PMID: 7306053 PMCID: PMC1162882 DOI: 10.1042/bj1950267] [Citation(s) in RCA: 109] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Glycoprotein from pig small-intestinal mucus was isolated free of non-covalently bound protein and nucleic acid with a yield of over 60%. No non-covalently bound protein could be detected by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis or by equilibrium centrifugation in a density gradient of CsCl with 4 M-guanidinium chloride. The intrinsic viscosity and reduced viscosity of the glycoprotein preparations rose with the removal of non-covalently bound protein and nucleic acid from the glycoprotein, evidence that non-covalently bound protein does not contribute to the rheological properties of the glycoprotein in the mucus. The pure glycoprotein, in contrast with impure preparations, gelled at the same concentration of glycoprotein as that present in the gel in vivo. The glycoprotein was a single component, as judged by gel filtration and analytical ultracentrifugation. The distribution of sedimentation coefficients was polydisperse but unimodal with an s025,w of 14.5S and a molecular weight of 1.72 X 10(6). The chemical composition of the glycoprotein was 77% carbohydrate and 21% protein, 52% of which was serine, threonine and proline. The glycoprotein had a strong negative charge and contained 3.1% and 18.3% by weight ester sulphate and sialic acid respectively. The molar proportion of N-acetylgalactosamine was nearly twice that of any of the other sugars present, the glycoprotein had A and H blood-group activity and the average maximum length of the carbohydrate chains was deduced to be six to eight sugar residues.
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LaMont JT, Ventola AS. Purification and composition of colonic epithelial mucin. BIOCHIMICA ET BIOPHYSICA ACTA 1980; 626:234-43. [PMID: 7459381 DOI: 10.1016/0005-2795(80)90214-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Colonic mucin was purified from homogenized scrapings of rat colonic epithelial cells using gel filtration and ion-exchange chromatography. High molecular weight water-soluble mucin was separated from low molecular weight proteins by gel exclusion chromatography on Sepharose 4B, and was further separated into two major mucin fractions and several non-mucin fractions on DEAE-cellulose. Fraction IV, the major mucin, was a sulphated glycoprotein with 62% carbohydrate by weight, and high concentrations of serine and threonine. A more acidic mucin, fraction V, had similar composition. Approx. 85% of the sialic acid of fractions IV and V were removed after incubation with Clostridium perfringens neuraminidase. Blood group A but not group H activity was present in fractions III, IV, and V. Ultracentrifugation experiments showed that fraction IV migrated as a single peak, whereas fraction V contained two components. Our study indicates that colonic mucin consists of at least two closely related acidic high molecular weight glycoproteins which can be separated from non-mucin contaminants by ion-exchange chromatography.
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17
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Slomiany B, Murty V, Slomiany A. Isolation and characterization of oligosaccharides from rat colonic mucus glycoprotein. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(18)43452-7] [Citation(s) in RCA: 83] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Marshall T, Allen A. The isolation and characterization of the high-molecular-weight glycoprotein from pig colonic mucus. Biochem J 1978; 173:569-78. [PMID: 697737 PMCID: PMC1185811 DOI: 10.1042/bj1730569] [Citation(s) in RCA: 78] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
1. A high-molecular-weight glycoprotein constitutes over 80% by weight of the total glycoprotein from water-soluble pig colonic mucus. 2. It was isolated from from nucleic acid and non-covalently bound protein by nuclease digestion followed by equilibrium centrifugation in a CsCl gradient. 3. The glycoprotein has the following composition by weight: fucose 10.4%; glucosamine 23.9%; galactosamine 8.3%; sialic acid 9.9%; galactose 20.8%; sulphate 3.0%; protein 13.3%; moisture about 10%. 4. The native glycoprotein has the high mol.wt. of 15 X 10(6). 5. Reduction of the native glycoprotein with 2-mercaptoethanol results in a glycoprotein of mol.wt. 6 X 10(6). 6. Pronase digestion removes 29% of the protein (3% of the glycoprotein) but none of the carbohydrate. 7. The molecular weight of the Pronase-digested glycoprotein is 1.5 X 10(6), which is halved to 0.76 X 10(6) on reduction with 2-mercaptoethanol. 8. The contribution of non-covalent interactions, disulphide bridges and the non-glycosylated peptide core to the quaternary structure of the glycoprotein are discussed and compared with the known structure of pig gastric glycoportein.
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Culling CF, Reid PE. The apparent failure of sodium borohydride reduction to block further PAS reactivity in rat epithelial mucins. THE HISTOCHEMICAL JOURNAL 1977; 9:781-5. [PMID: 924810 DOI: 10.1007/bf01003072] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Sections of rat small intestine were oxidized with 1% periodic acid for periods of 1, 2, 5, 10 and 30 min and were subsequently either (a) stained with Schiff reagent, or (b) reduced with sodium borohydride and then treated with either Schiff reagent alone or by the standard PAS procedure. It was found that whereas sodium borohydride reduction abolished all Schiff staining, initial periods of oxidation in excess of 10 min were necessary to abolish any subsequent PAS reactivity. The theoretical and practical significance of these data is discussed in relation to the recent publication of Bayliss & Adams (1976).
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Culling CF, Reid PE, Dunn WL, Clay MG. Histochemical comparison of the epithelial mucins in the ileum in Crohn's disease and in normal controls. J Clin Pathol 1977; 30:1063-7. [PMID: 73552 PMCID: PMC476652 DOI: 10.1136/jcp.30.11.1063] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
A comparison of routine and special histochemical methods that were applied to the epithelial mucins of small intestine from patients with Crohn's disease and from normal controls showed that the normal small intestine (ileum) goblet cells secrete a predominantly non-sulphated sialomucin and that, in contradistinction to the colon, the neuraminidase insensitivity of the sialic acids of the small intestine was not due to either O-acylation at C4 or an ester substituent at C1. Presumably this implies that the protection against enzyme attack afforded to the mucosa by the mucin coat in the small intestine utilises a different mechanism from that in the colon and that, although in many respects the small intestinal mucins in Crohn's disease, and in normal controls are similar, there is an increase in side-chain O-acylated sialic acids in such mucins in Crohn's disease. This difference has not been described before, probably because it can be seen only after staining such sections by the PAT/KOH/PAS and the PBT/KOH/PAS techniques.
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Forstner G, Sturgess J, Forstner J. Malfunction of intestinal mucus and mucus production. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1977; 89:349-69. [PMID: 930727 DOI: 10.1007/978-1-4613-4172-7_24] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Kim YS, Brophy EJ. Rat intestinal brush border membrane peptidases. I. Solubilization, purification, and physicochemical properties of two different forms of the enzyme. J Biol Chem 1976. [DOI: 10.1016/s0021-9258(17)33423-3] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Kim YS, Brophy EJ, Nicholson JA. Rat intestinal brush border membrane peptidases. II. Enzymatic properties, immunochemistry, and interactions with lectins of two different forms of the enzyme. J Biol Chem 1976. [DOI: 10.1016/s0021-9258(17)33424-5] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Martin A, Louisot P. Biosynthesis of glycoproteins in the intestinal Mucosa3-I. Soluble state of five glycosyl-transferases. ACTA ACUST UNITED AC 1976. [DOI: 10.1016/0020-711x(76)90052-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Huguet R, Solère M, Remy-Heintz N. [Isolation and composition of a glycoprotein from lamb gastric mucosa]. Biochimie 1975; 57:105-12. [PMID: 1148317 DOI: 10.1016/s0300-9084(75)80116-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A glycoprotein is isolated from lamb gastric mucosa. It is purified first by reduction with dithiothreitol and then by chromatography on CM-Sephadex followed by gelfiltration on Sephadex G-75. Its homogeneity is investigated by disc electrophoresis, immunoelectrophoresis, analytical ultracentrifugation and identification of the carboxy- and amino-terminal amino acids. This glycoprotein contains 56 p. cent carbohydrates, consisting of N-glycolyneuraminic acid, fucose, galactose, and hexosamines. Hexosamines and galactose are in equimolar ratio ; galactosamine and glucosamine in the ratio 1 :2. The amino acid composition shows that threonine, serine and proline account for half of the amino acid residues. The cysteine origin and function are discussed.
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Abstract
The effects of mucin on cholera toxin induced intestinal secretion was studied in the rat small intestine. Gastric mucin inhibited secretion when premixed with cholera toxin on an equal dry-weight basis. Neither salivary nor intestinal mucin inhibited the toxin's action in the intestine. Inhibition by gastric mucin was not reversed by a mucolytic agent or by hexoses or agents that bind hexoses. Plasma and serum did not inhibit the effects of cholera toxin in the intestine. Choleragen was labeled with (14)C and its binding to mucins and ganglioside was studied. Gastric mucin was shown to bind to choleragen, but less binding was observed when choleragen was dissociated into subunits by acid pH. Salivary and intestinal mucins bound intact choleragen but not the subunits at acid pH. Salivary mucin binding was reversed by N-acetyl neuraminic acid and neuraminidase. Ganglioside bound choleragen in both the intact and dissociated forms. Binding to the dissociated form was reversed by wheat germ agglutinin. Gastric mucin and ganglioside competed for binding to choleragen with the binding of intact choleragen greater for ganglioside and the affinity of the subunits greater for gastric mucin. Electrophoresis of labeled choleragen showed uniform labeling of the subunits dissociated by acid pH, but a major part of cholera toxin was found not to be labeled when fractionated with sodium dodecyl sulfate and 2-mercaptoethanol.
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Salter DN, Fulford RJ. The influence of the gut microflora on the digestion of dietary and endogenous proteins: studies of the amino acid composition of the excreta of germ-free and conventional chicks. Br J Nutr 1974; 32:625-37. [PMID: 4433506 DOI: 10.1079/bjn19740115] [Citation(s) in RCA: 45] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
1. To assess the part played by the microflora in the digestion of proteins, the amino acid composition of the excreta and the apparent and true digestibilities of individual amino acids were measured in germ-free (GF) and conventional (CV) chicks.2. Three diets were used: diet 1, nitrogen-free; diet 2,280 g protein/kg as (g/kg): casein 80, gelatin 100 and freeze-dried egg albumen 100 and diet 3,280 g protein/kg as diet 2 but with heat-damaged instead of freeze-dried egg albumen. Half of the GF and half of the CV chicks received the N-free diet in the first 7 d of test and the other half of each group received either diet 2 or diet 3. In the second 7 d test period those chicks which had been given the N-free diet received either diet 2 or diet 3 while those which had been given protein diets received the N-free diet. Total amino acids were measured in hydrolysates of the soluble and insoluble fractions of the excreta collected in the last 3 d of each test period.3. The amino acid composition of the soluble fraction of the excreta of chicks given either diet 2 or diet 3 differed markedly from that of chicks given the N-free diet. The amino acid composition of the insoluble fraction of the excreta of chicks given diet 2 was similar to that of chicks given the N-free diet, whereas that of chicks given diet 3 was markedly different and resembled egg albumen in composition.4. In the soluble fraction of excreta from CV chicks given diets 1 and 2 the proportions of threonine, serine and glucosamine were lower and those of methionine, leucine, isoleucine and phenylalanine were higher than in those from GF chicks, particularly on diet 1. In the insoluble fraction of excreta from CV chicks given these two diets, compared with GF chicks, there were lower proportions of serine and proline and higher proportions of cysteic acid and lysine, the latter particularly with diet 1.5. Lower proportions of threonine, serine and glucosamine were also observed in the soluble fractions of excreta from the CV chicks given diets 1 and 3, compared with GF chicks, whereas the proportion of glutamic acid was higher. With these two diets the insoluble fraction from CV chicks contained a higher proportion of alanine. In each instance the environmental effect was greater with diet 1.6. No effect of environment on either apparent or true digestibility of individual dietary protein amino acids was demonstrated, with the exception of threonine in diet 2, the true digestibility of which was higher in GF than in CV chicks.7. It was concluded that the gut microflora of the chick had little influence on the digestion of the proteins in the diets tested, but may serve an important role in the degradation of endogenous proteins and the recycling of N.
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Kleinman HK, Wolf G. Extraction and characterizaiton of a "native" vitamin A-sensitive glycoprotein from rat intestine. BIOCHIMICA ET BIOPHYSICA ACTA 1974; 359:90-100. [PMID: 4847578 DOI: 10.1016/0005-2795(74)90135-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Etzler ME. Use of plant agglutinins in characterization of glycoproteins and glycolipids from mammalian cells. Ann N Y Acad Sci 1974; 234:260-75. [PMID: 4607334 DOI: 10.1111/j.1749-6632.1974.tb53038.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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