Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “HEXOSAMINES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,441 records · Page 80Linked to original sources
PubMed1991

Diagnostic methods for the determination of iduronic acid in oligosaccharides.

A high-performance liquid chromatography (HPLC) method with pulsed amperometric detection (PAD) was used for the determination of the acid hydrolysis products of L-iduronic acid containing oligosaccharides isolated from biological sources. This HPLC-PAD method was compared with gas chromatographic (GLC) methods. Since acid hydrolysis of oligosaccharides can produce a number of products, several uronic acid derivatives were prepared by chemical synthesis. These well characterized standards in conjunction with mass spectrometry allowed for the identification of most of the products of methanolysis or hydrolysis of glycosamino-glycans, which included chondroitin sulfates A and B (dermatan sulfate), heparin, and hyaluronic acid. (4 M) HCl in methanol 100 degrees C for 24 h was found to be optimum for GLC and 1 M aqueous HCl for 4 h at 100 degrees C for HPLC-PAD. All of the monosaccharides, hexosamines, and uronic acids could be separately identified in a single chromatographic step using either technique. Good resolution, high sensitivity (low microgram samples) and rapid analysis makes these methods particularly useful for the determination of small amounts of glycosaminoglycans and other glycoconjugates found in samples isolated from biological sources. These two techniques are specifically designed to allow the qualitative determination of the carbohydrate content and composition of samples whose carbohydrate composition and content is completely unknown.

Chondroitin Sulfates↗
PubMed1991

Quantitative determination of phenyl isothiocyanate-derivatized amino sugars and amino sugar alcohols by high-performance liquid chromatography.

Simple and rapid methods for the preparation of phenylthiocarbamyl (PTC) derivatives of amino sugars and amino sugar alcohols and their quantitative determination with high sensitivity (less than 10 pmol) by C18 reversed-phase high-performance liquid chromatography are described. Rapid sample preparation of the phenyl isothiocyanate (PITC)-derivatized amino sugars and amino sugar alcohols was achieved by a simple extraction of the reaction mixture with chloroform to remove the excess PITC and its adducts. Baseline separation of the PTC derivatives of amino sugars and amino sugar alcohols was obtained within 30 min, using a simple solvent system consisting of 0.2% each of n-butylamine, phosphoric acid, and tetrahydrofuran. The mobile phase containing n-butylamine, in conjunction with a C18 stationary phase, mimics the conditions for the separation of carbohydrates on an amino-bonded column. GlcNH2 and GalNH2 derived from the initial protein-sugar linkages were also separated from the amino acids for quantitative estimation of sugar chains in glycoproteins. Amino sugar alcohols gave single reaction products with PITC while the reaction with amino sugars was accompanied by the formation of secondary products. Apparently the secondary products were formed in an acid-catalyzed intramolecular cyclization of the PTC-hexosamines involving the aldehyde functional group. Conditions were developed to stop the transformations and maintain the stability of PTC derivatives for their convenient determination by HPLC.

Amino Sugars↗
PubMed1985

Structural elucidation of glycosaminoglycans through characterization of disaccharides obtained after fragmentation by hydrazine-nitrous acid treatment.

Hydrazinolysis of glycosaminoglycans to bring about N-deacetylation followed by nitrous acid treatment to effect deaminative cleavage at alternating hexosamine residues has been used to make possible identification and quantitation of disaccharide sequences and position of O-sulfate substitution in nanogram amounts of these polymers. After radiolabeling by NaB3H4 reduction the hydrazine-nitrous acid products were fractionated on Dowex 1 and further resolved by thin-layer chromatography into disaccharides terminating in either sulfated or unsulfated anhydromannitol or anhydrotalitol. Fragmentation of hyaluronic acid, keratan sulfate, chondroitin 4-sulfate, chondroitin 6-sulfate, dermatan sulfate, and heparin yielded a total of 14 disaccharides comprising the major sequences (greater than 1 mol%) occurring in mammalian glycosaminoglycans. Disaccharides representing the predominant variants of the chondroitin sulfates [GlcUA beta 1----3anhydrotalitol(4-SO4) and GlcUA beta 1----3anhydrotalitol(6-SO4)] as well as of dermatan sulfate chains [IdUA alpha 1----3anhydrotalitol(4-SO4) and GlcUA beta 1----3anhydrotalitol(4-SO4)] chains could readily be quantitated by this approach. In the case of heparin a comparison of the disaccharides produced by direct nitrous acid and hydrazine-nitrous acid treatments moreover provided an assessment of the distribution of N-sulfate groups. The characterization of the various disaccharides by Smith periodic acid degradation and glycosidase digestions was facilitated by the preparation and thin-layer chromatographic resolution of the complete series of monosulfated derivatives of anhydromannitol and anhydrotalitol; the sulfate esters were shown to be stable to both the hydrazine and nitrous acid treatments. The high sensitivity of the hydrazine-nitrous acid fragmentation procedure should prove useful in the structural elucidation of cell surface and basement membrane proteoglycans as well as other sulfated glycoconjugates which are present in small amounts.

Animals↗
PubMed1985

Purification and partial characterization of ceruloplasmin from chicken serum.

The preparation and properties of ceruloplasmin from chicken serum are described. Ethanol-CHCl3 was used to precipitate the crude protein, followed by adsorption and elution from DEAE-Sephadex. Further treatment with Sephadex G-200 and CM-Sephadex yielded an intensely blue protein judged 1572-fold purer than starting serum. epsilon-Aminocaproic acid (0.02 M) was present in all buffers and starting sera. Chicken ceruloplasmin appears to be a single polypeptide, apparent Mr 124,000, with an A610/A280 ratio of 0.07 and an absorption maximum at 602 nm. Hexose, hexosamine, and sialic acid accounted for 7.2% of the weight; copper represented 0.20%, which suggested four or five copper atoms per molecule. Chicken ceruloplasmin catalyzed the azide-sensitive oxidation of p-phenylenediamine (PPD) and N,N'-dimethyl-p-phenylenediamine (DPD), and showed ferroxidase activity similar to that of human ceruloplasmin. Its amino acid composition, although similar in many residues to human ceruloplasmin, was decidedly lower in methionine and tyrosine. The chicken protein had one-third the sialic acid content of human ceruloplasmin and showed immunochemical nonidentity with human ceruloplasmin.

Amino Acids↗
PubMed1988

Purification and partial characterization of goose ceruloplasmin.

The preparation and properties of ceruloplasmin from goose blood plasma are described. Ammonium sulfate was used to precipitate the crude protein followed by adsorption and elution from DEAE-Sephadex A-50. Further treatment with an ethanol-chloroform mixture and Sephadex G-200 yielded an intensely blue protein possessing a high degree of chemical purity and biological activity. Goose ceruloplasmin, existing in two forms, appears to be a single polypeptide, apparent Mr121,300, with an A610/A280 ratio of 0.07. Copper represented 0.32%, which corresponded to six atoms of copper per protein molecule. Although the amount of EPR-detectable copper was the same as in mammalian ceruloplasmins there were some differences in EPR parameters, mainly in A parallel. Goose ceruloplasmin's amino acid composition, although similar in many residues to human ceruloplasmin, was lower in tyrosine, cystine/cysteine, and acidic amino acids. Valine was found as the N-terminal amino acid. Hexose, hexosamine, sialic acid, and fucose accounted for 6.65% of the weight. Goose protein contained only half the sialic acid of human ceruloplasmin. Two values for Km using either p-phenylenediamine (0.64 and 0.053 mM) or o-dianisidine (0.76 and 0.15 mM) were evaluated from Lineweaver-Burk plots. EPR studies on reactions with water radiolysis products at cryogenic temperatures allowed us to discover that goose ceruloplasmin, like human and bovine ceruloplasmins, possesses superoxide dismutase activity.

Amino Acids↗
PubMed1989

Phosphorylation-dependent regulation of amidotransferase during the development of Blastocladiella emersonii.

The enzyme amidotransferase [2-amino-2-deoxy-D-glucose-6-phosphate ketol isomerase (amino-transferring); EC 2.6.1.16] catalyzes the first step in the hexosamine biosynthetic pathway. In Blastocladiella emersonii the sensitivity of the enzyme to the inhibitor uridine-5'-diphospho-N-acetylglucosamine (UDP-GlcNAc) is developmentally regulated. The inhibitable form of amidotransferase activity present in the zoospore is converted to a noninhibitable form during germination. The latter form is present throughout the growth phase and sensitivity to UDP-GlcNAc gradually returns to the zoospore level during sporulation [C.P. Selitrennikoff, N.E. Dalley, and D.R. Sonneborn (1980) Proc. Natl. Acad. Sci. USA 77, 5998-6002]. The following evidence suggests that a phosphorylation/dephosphorylation mechanism underlies this interconversion: (i) Both the vegetative and zoospore enzymes have the same molecular weight of 140,000, but the vegetative enzyme elutes significantly earlier on a DEAE-cellulose column than does the zoospore enzyme. (ii) The increased sensitivity to UDP-GlcNAc occurring in vivo and in vitro correlates with increased phosphorylation of a polypeptide of apparent Mr 76,000. This component copurifies with amidotransferase activity through ion-exchange chromatography and sucrose density gradient centrifugation. (iii) Desensitization and concurrent dephosphorylation of sensitive amidotransferase can be observed in vitro after treatment with a partially purified magnesium-dependent phosphoprotein phosphatase from zoospores.

Blastocladiella↗
PubMed1983

Composition of human palatine gland secretions and evidence for the presence of specific arylamidases.

After mechanically stimulating the surface of palatine mucosa of adult human subjects, 10-25 microliter of saliva secreted from the openings of the palatine glands were directly collected into graduated glass capillaries. The saliva samples contained large amounts of carbohydrates, sialic acids and hexosamines as a result of the high glycoprotein content of the secretions. The saliva did not show activity from amylase, peroxidase, lysozyme and other typical mixed saliva enzymes, but contained arylamidases at concentrations much higher than mixed saliva from the same subjects.

Adult↗
PubMed1979

Isolation and partial characterization of glycolipids and a carbohydrate from the secondary granules and plasma membrane of polymorphonuclear leukocytes.

Chloroform/methanol extracts of the secondary granule and plasma membrane fractions of polymorphonuclear leukocytes have been shown to contain both non-polar and polar carbohydrate-containing materials. The ratio of the polar to the non-polar material was much higher in the plasma membrane than the secondary granule fraction. The non-polar material contains at least two ceramide-like glycolipids and accounts for most of the broad band of periodic acid/Schiff-positive material which migrates at the dye front in sodium dodecyl sulfate electrophoretic gels of granule and plasma membrane extracts. The polar material appears to be a single substance containing no fatty acids or sialic acid and is composed of glucose, hexosamine and a carboxylic acid derivative of pentose. Expressed on a per mg of protein basis, the amount of carbohydrate associated with the polar material in the plasma membrane fraction was about five times that of the secondary granule fraction.

Animals↗
PubMed1980

Cell surface proteoglycans as a negative modulator in concanavalin A-mediated agglutination of hepatoma cells.

Proteoglycan (heparan sulfate-protein conjugate) was solubilized with 8 M urea from rat liver plasma membranes after enzymic (RNAase, neuraminidase) treatments and extensively purified by chromatography and gel filtration. The final products gave an average ratio of hexuronate to protein (weight) of approx. 1.5, contained hexosamine equimolar to hexuronate and were sensitive to beta-elimination (the molecular weight being reduced from 20 . 10(4) to 3 . 10(4) (gel filtration)). The proteoglycan fraction, when added to trypsinized and untrypsinized ascites hepatoma (AH-130F(N)) cells, inhibited the concanavalin A-mediated agglutination of the cells. However, the alkali-treated proteoglycan (beta-elimination) or acid mucopolysaccharide fraction prepared from liver plasma membranes by papain digestion were less effective, and a reference preparation of heparan sulfate was almost ineffective. It was confirmed that significant amounts of proteoglycan labelled with 35SO4(2-) were firmly bound to or taken up by the trypsinized ascites hepatoma cells. These results together with the sensitization of lectin-mediated agglutination by mild protease treatment of cells suggest that cell surface proteoglycans may act as a negative modulator in the lectin-mediated agglutination of cells.

Animals↗
PubMed1980

Hydrodynamic properties of solubilized (Na+ + K+)-ATPase from rectal glands of Squalus acanthias.

(1) (Na+ + K+)-ATPas from the rectal glands of Squalus acanthias, solubilized in octaethylene glycol dodecyl monoether (2 mg detergent/mg protein), retains its activity for days when stored at 0 degrees C both with and without 20% glycerol. Glycerol protects partially against inactivation at higher temperatures. (2) Solubilization leads to a decrease in the amount of lipids bound per mg protein. 50 mol phospholipids and 40 mol cholesterol are bound per 265 000 g protein. 90% of the phospholipid is phosphatidylcholine (72%) and phosphatidylethanolamine (18%) and there is about 1 mol acidic phospholipid per 265 000 g. In addition, the protein has about 27 000 g carbohydrate as hexose, hexosamine and sialic acid bound per 265 000 g. (3) The calculation of the molecular weight from an In C vs. r2 plot obtained by sedimentation equilibrium centrifugaton in the presence of 560 microM detergent gives a molecular weight of the protein part of the active solubilized enzyme of 265 000 using the measured values for bound detergent, lipid (phospholipid + cholesterol) and carbohydrate. The sedimentation coefficient (S20,w) is 10.1 S, giving a Stokes' radius of 77 A. (4) An increase in detergent concentration to 56 mM dissociates the 10.1 S particle into particles with a sedimentation coefficient of 5.8 S and a molecular weight of 139 000 (Stokes' radius, 66 A). In the presence of this detergent concentration the enzyme is inactive. (5) The molecular weights of the soijm dodecyl sulphate-solubilized, isolated alpha- and beta-chains are found to be 106 000 and 40 000, respectively. (6) It is concluded that the active solubilized enzyme is an (alpha beta)2 structure and that it dissociates into an enzymatically inactive alpha beta structure when the detergent-to-protein ratio is increased.

Animals↗
PubMed1981

Steps in the biosynthesis of mosquito cell membrane glycoproteins and the effects of tunicamycin.

A cultured cell line of the mosquito, Aedes aegypti, is sensitive to tunicamycin as expected from the ability of crude membrane preparations to catalyse the formation of N-acetylglucosamine-linked dolichyl pyrophosphate. Formation of dolichylphosphomannose was also detected and this reaction was totally insensitive to tunicamycin. Incorporation of radioactive mannose into total acid-precipitable glycoproteins was inhibited greater than 90% in whole cells by tunicamycin, while the incorporation of leucine and glucosamine was less affected. Separation of the radioactive hexosamines from acid hydrolysates of cells incubated with [14C]glucosamine and tunicamycin showed predominant labelling of galactosamine, whereas in control cells not treated with the drug both glucosamine and galactosamine were labelled equally. Evidently, mosquito cells synthesise N-glycosidically linked carbohydrate chains assembled through tunicamycin-sensitive steps involving dolichyl pyrophospho-oligosaccharides, and O-glycosidically linked chains rich in N-acetylgalactosamine, the assembly of which is unaffected by tunicamycin. These results support structural evidence (Butters, T.D. and Hughes, R.C. (1981) Biochim. Biophys. Acta 640, 655-671) for the presence of high mannose N-glycans and N-acetylgalactosamine-rich O-glycans in mosquito cell glycoproteins. The absence of complex N-glycans was confirmed by the demonstration of negligible activities of N-acetylglucosaminyl-, galactosyl- and sialyltransferases responsible for assembly of the terminal sequences of N-glycans of mature mammalian glycoproteins.

Aedes↗
PubMed1981

Microvillus membrane vesicles from pig small intestine. Purity and lipid composition.

Microvillus membrane vesicles from pig small intestine were isolated by a method based on hypotonic lysis, Mg2+-aggregation of contaminants and differential centrifugation. The purity of the membrane vesicles were established by measuring the activity of marker enzymes and the RNA and DNA content. The membranes were found free of contamination by other subcellular membrane fragments, except for a minor contamination with basolateral plasma membranes. The lipid composition was established and, based on weight percentage, the membrane contained neutral lipids, phospholipids, neutral glycolipids and gangliosides in the weight ratio of 18 : 50 : 29 : 2%. The amount of individual phospholipids and glycolipids were quantitated. Phosphatidylethanolamine, -choline, -serine, -inositol and sphingomyelin made up 17, 17, 6, 5 and 5%, respectively of the total lipid. The major glycolipids were two monohexosylceramides containing glucose and galactose as the carbohydrate component, a dihexosylceramide containing galactose as the only carbohydrate component and two pentahexosylceramides containing fucose, galactose, glucose and hexosamine (either N-acetylglucosamine or N-acetylgalactosamine) in the molar ratio of 1 : 2 : 1 : 1.

Alkaline Phosphatase↗
PubMed1981

Isolation, characterization and chemical composition of the membrane from sheep platelets.

A procedure of the isolation of platelets from the blood of adult sheep (Ovis aries L. var domestica) is reported. This procedure is based on differential centrifugation and a specific lysis for elimination of erythrocytes. We have obtained platelets with a purity at least 99% and a relative high yield (2.3 +/- 0.4 g wet/l whole blood identical to 235 +/- 40 mg platelet proteins/l whole blood). After disruption, homogenisation and ultracentrifugation onto a discontinuous sucrose gradient (1.6 M, 1.1 M, 1.0 M and 0.6 M sucrose), four fractions were obtained. We have separated, for the first time, a particulate preparation enriched in the whole sheep plasma membrane. This fraction was characterized by: (i) the typical membrane morphology as shown by electron micrographs; (ii) the highest activities in membrane marker enzymes such as bis(p-nitrophenyl)phosphate phosphodiesterase (EC 3.1.16.1) and 5'-dTMP-p-nitrophenyl ester phosphodiesterase (EC 3.1.3.35), and the relatively low activity for marker enzymes associated to other subcellular fractions; (iii) the highest sialic acid, cholesterol and phospholipid concentrations. The chemical composition of the platelet membrane isolated is: total proteins, 49%; lipids, 47%; carbohydrates, congruent to 3.4% (the content of hexoses is twice as high as that of hexosamines and sialic acid). The similarities and differences of this preparation with others from several sources are discussed.

Animals↗
PubMed1978

Purification and comparative properties of the glycoprotein nicotinamide adenine dinucleotide glycohydrolase from rat liver microsomal and plasma membranes.

NAD glycohydrolase, or NADase (NAD+ glycohydrolase, EC 3.2.2.5) was solubilized with porcine pancreatic lipase from isolated fractions of microsomes and plasma membranes obtained from rat livers. The enzyme from each organelle was further purified by DEAE-cellulose chromatography, gel filtration and isoelectric focusing. The solubilized, partially purified enzymes had similar molecular weights, pH-activity profiles and Km values. Marked charge heterogeneity was observed for the microsomal enzyme on isoelectric focusing between pH 6 and 8 with maximum activity focusing at pH 8.0. Plasma membrane NADase displayed a single peak at pH 6.7. Treatment of the partially purified microsomal or plasma membrane enzyme with neuraminidase resulted in a single peak of activity on isoelectric focusing (pH 3.5--10) with a pI of 9.2. Polyacrylamide gel electrophoresis of either NADase revealed a periodate-Schiff positive band which was coincident with enzyme activity. Compositional analyses of the microsomal enzyme focusing at pH 8.0 confirmed the presence of hexoses, hexosamines and sialic acid. Differences in carbohydrate composition might be important in determining the subcellular distribution of this enzyme.

Animals↗
PubMed1978

Some physicochemical and structural properties of two beta-fucosidases from Achatina balteata.

Some properties of two beta-fucosidases from the digestive juice of a giant snail Achatina balteata were studied. Their amino acid composition was similar and both enzymes were shown to be rich in acidic and aromatic residues. Alanine was the single N-terminal residue in the two molecules. The enzymes appeared to be devoid of sialic acid but to contain galactose, glucose, mannose, fucose and hexosamines. The total sugar content was higher in beta-fucosidase I (21.6% w/w) than in beta-fucosidase II (12.7% w/w). Gel filtration and ultracentrifugation assays were consistent with an apparent molecular weight higher than 300 000 for beta-fucosidase I and of about 110 000 for beta-fucosidase II. On SDS polyacrylamide gel electrophoresis, beta-fucosidase I dissociated into two subunits (mol. wt. 190 000 and 170 000), whereas beta-fucosidase II showed a single band with a mol. w. of about 110 000. On the basis of these studies, it is concluded that the two forms are not structurally related proteins.

Amino Acids↗
PubMed1979

Purification and some properties of liver and brain beta-N-acetyl-hexosaminidase S.

beta-N-Acetyl-hexosaminidase S (2-acetamido-2-deoxy-beta-hexoside acetamido-deoxyhexohydrolase, EC 3.2.1.52) was purified from liver and brain of a patient deceased of type O GM2 gangliosidosis (Sandhoff's disease). Brain beta-N-acetyl-hexosaminidase S was further purified by preparative polyacrylamide gel electrophoresis. The pH optimum of the purified liver and brain enzyme was 5.0 and Km values were 0.8--0.9 mM and 0.3--0.4 mM with 4-methylumbelliferyl-beta-D-N-acetylglucosamine and beta-D-N-acetylgalactosaminide derivatives, respectively. beta-N-Acetyl-hexosaminidase S was thermolabile losing most of its activity after 50 min at 50 degrees C. The apparent molecular weights of the purified liver and brain enzymes were 154 000 and 152 000, respectively. Hexosamines activated beta-N-acetyl-hexosaminidase S whereas the isoenzyme A and B were inhibited. The glycoprotein nature of beta-N-acetyl-hexosaminidase S was suggested by its affinity towards Concanavalin A-Sepharose.

Binding Sites↗
PubMed1976

The glycosphingolipids of rat sublingual and submaxillary glands.

1. Glycosphingolipids have been isolated from rat sublingual and submaxillary glands by the procedure involving lipid extraction, column fractionation and thin-layer chromatography. 2. The major neutral glycosphingolipids in rat sublingual and submaxillary glands were monohexosylceramide, dihexosylceramide, tetrahexosylceramide and pentahexosylceramide. Both types of glands exhibited a low content of trihexosylceramide. The fucose-containing glycosphingolipids were not found. 3. The acidic glycosphingolipids in rat sublingual and submaxillary glands were composed of monohexose sulfatide, dihexose sulfatide and monosialo-and disialogangliosides of hematoside series. In addition, small quantities of gangliosides containing hexosamines were also present. 4. The distribution of acidic and neutral glycosphingolipids was similar in the sublingual and submaxillary glands, except for the tetrahexosylceramide and sultatides. Sublingual glands contained 1.5 and 3.0 times as much tetrahexosylceramide and sulfatides, respectively, as did submaxillary glands. 5. The glycosphingolipids of submaxillary and sublingual glands showed large similarity in fatty acid composition. The fatty acid composition of gangliosides resembled each other, but differed remarkably from those of sulfatides and neutral glycosphingolipids in the docosanoate content.

Animals↗
PubMed1986

Isolation and characterization of lecithin-cholesterol acyltransferase from hog plasma.

Lecithin-cholesterol acyltransferase (EC 2.3.1.43) was purified from hog plasma by a highly efficient procedure. The final enzyme preparation was purified 30,000-fold over the starting material and was homogeneous as indicated by polyacrylamide gel electrophoreses in the presence of both SDS and urea. The purified hog lecithin-cholesterol acyltransferase had an apparent molecular weight of 66 000 on SDS-polyacrylamide gel electrophoresis and HPLC and was found to contain about 21.4% (w/w) carbohydrate-hexose, 11.3%; hexosamine, 1.9%; sialic acid, 8.2%. The amino acid composition analysis showed that hog lecithin-cholesterol acyltransferase contains four half cystines per mol; two cysteines were titrated at neutral pH with 5,5'-dithiobis(2-nitrobenzoic acid). Nearly all the phenolic groups were unavailable to the solvent at neutral pH, while they become exposed at around pH 11. Hog lecithin-cholesterol acyltransferase was found to be associated with HDL in the plasma and it prefers HDL as a substrate. The physicochemical properties of hog lecithin-cholesterol acyltransferase were generally similar to those of the human and the rat enzyme.

Amino Acids↗