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:3.2.1.23 (beta-galactosidase)
14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The biosynthesis of galactosyl-beta 1,3-N-acetylglucosamine has been demonstrated using membrane preparations from pig trachea. Unlike the UDP-galactose:2-acetamido-2-deoxy-D-glucose 4 beta-galactosyltransferase, which is inhibited by high levels of N-acetylglucosamine, the UDP-galactose:N-acetylglucosamine 3 beta-galactosyltransferase shows no inhibition at 200 mM N-acetylglucosamine. About 80% of the total disaccharide synthesized at 200 mM N-acetylglucosamine was base-labile suggesting the 1,3-linkage, alpha-Lactalbumin inhibits galactose incorporation into galactosyl-beta 1,4-N-acetylglucosamine but has little or no effect on the activity of the 1,3-galactosyltransferase. Escherichia coli beta-galactosidase readily hydrolyzed the base-stable product, but not the base-labile component. The apparent 1,3-linked disaccharide was reduced with NaBH4 and was isolated by Bio-Gel P-2 column chromatography. Methylation analysis by gas chromatography/mass spectrometry showed tetramethyl galactose and a 3-substituted N-acetylglucosaminitol. Neither the beta 1,4 nor the beta 1,3 disaccharide was hydrolyzed by green coffee bean alpha-galactosidase. Both disaccharides were readily hydrolyzed by bovine testes beta-galactosidase. This is the first report on the galactosyltransferase which catalyzes the synthesis of the galactosyl-beta 1,3-N-acetylglucosamine linkage such as found in the Type I chain of human blood group substances. A tissue survey in rats showed only rat intestine to have readily detectable UDP-galactose: N-acetylglucosamine 3 beta-galactosyltransferase activity. The intestinal membrane fraction like the tracheal enzyme catalyzes the synthesis of two disaccharides as judged by base treatment, and these appear to be the beta 1,3 and beta 1,4 isomers of galactosyl-N-acetylglucosamine.
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PMID:Biosynthesis of galactosyl-beta 1,3-N-acetylglucosamine. 627 54

The synthesis of glycoproteins containing N-linked complex oligosaccharides is blocked by swainsonine at the step catalyzed by Golgi mannosidase II (Tulsiani, D. R. P., Harris, T. M., and Touster, O. (1982) J. Biol Chem. 257, 7936-7939). Accordingly, hybrid glycoproteins might be produced in the presence of swainsonine. In this report, we demonstrate that swainsonine causes human skin fibroblasts to synthesize such glycoproteins. In control fibroblasts, there were approximately equal amounts of complex and high mannose glycoproteins. In the presence of swainsonine (10 micrograms/ml), most of the complex glycoproteins were replaced by hybrid types. The principal oligosaccharide had the following structure: (formula; see text) A smaller amount of the asialo hybrid was also produced. The structure of the hybrid was established by Bio-Gel P-4 fractionation of oligosaccharides produced by endoglycosidase H treatment of pronase-derived glycopeptides, followed by examination of the susceptibility of the oligosaccharide to glycohydrolases and by its adsorbability to serotonin-Sepharose 4B. The same hybrid oligosaccharide was produced efficiently by rat liver Golgi membranes in the presence of ([3H] Man)5GlcNAc, UDP-GlcNAc, UDP-Gal, CMP-NeuAc, and swainsonine. Golgi mannosidase II had no action on the hybrid oligosaccharide, and little action on asialo hybrid, but both were converted to the mannosidase II substrate, GlcNAcMan5GlcNAc, by appropriate treatment with neuraminidase and beta-galactosidase. Jack bean alpha-D-mannosidase gave the expected yields of free mannose from the various oligosaccharides studied in this work. Swainsonine should be useful in investigating the role of oligosaccharide structure of glycoproteins because of its ability to alter the oligosaccharide.
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PMID:Swainsonine causes the production of hybrid glycoproteins by human skin fibroblasts and rat liver Golgi preparations. 640 79

Structural studies are reported on seven hybrid proteins produced by gene fusions that contain a "foreign" amino acid sequence substituting for part of the NH2-terminal region of the beta-galactosidase polypeptide. All of these hybrid proteins retain beta-galactosidase enzyme activity. A simple and rapid purification scheme for the hybrid beta-galactosidase is described, involving ammonium sulfate fractionation, DEAE-Bio-Gel, and Bio-Gel A-1.5 chromatography. The proteins are tetramers and have activity equivalent to that of wild type enzyme. Their amino acid sequences were determined by isolation and sequence determination of the cyanogen bromide peptide containing the joining site. The subunit sizes vary from 1009 to 1355 residues compared to 1023 for wild type. Up to 26 amino acid residues at the NH2 terminus of beta-galactosidase can be substituted by the new sequence. The nature of the new sequence apparently has no influence on stability or activity of the hybrid, but those hybrids with more of the beta-galactosidase sequence deleted are less stable to heat or urea treatment and tend to dissociate to dimeric form. All hybrids are less stable to heat and urea than wild type. Antipeptide antibodies raised against peptides derived from the NH2-terminal region of wild type beta-galactosidase were found to bind to the hybrid proteins, although they do not bind to the normal enzyme. These results indicate that the quaternary structure is disturbed but not disrupted by substitution of the different sequence, and these results help to localize one of the intersubunit contact regions in beta-galactosidase.
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PMID:Purification, structure, and properties of hybrid beta-galactosidase proteins. 641 39

Three major glycoproteins of calf thyroid plasma membranes were preferentially solubilized by chloroform/methanol extraction and recovered along with glycolipids in the aqueous phase. After removal of lipid from this extract, a fraction was obtained which accounted for about 20% of the carbohydrate of the membrane but only 2% of its peptide weight. Partial resolution of the components could be achieved by filtration on Bio-Gel A-5m, while preparative polyacrylamide gel electrophoresis resulted in the isolation in homogeneous form of approximately equal amounts of the three glycoproteins which were designated as GP-1, GP-2, and GP-3, in order of their increasing mobility. These purified glycoproteins appeared on electrophoresis as single components by periodic acid-Schiff staining as well as by distribution of radioactivity following 3H or 14C labeling. Molecular weights of 100,000, 59,000, and 20,000 were estimated for the three components on the basis of their retardation coefficients. The total carbohydrate content by weight determined for GP-1, GP-2, and GP-3 was 56, 57, and 79%, respectively. The sugar constituents were mannose, galactose, fucose, glucosamine, galactosamine, and sialic acid, which were present in the following mol per cents: GP-1, 13:32:5:24:13:12; GP-2, 20:28:3:32:5:11; GP-3, 12:36:2:34:6:10. Studies performed with various lectins (Bandeiraea simplicifolia I and I (B4), wheat germ, Ricinus communis, and soybean) on the gycoproteins, either native or after treatment with glycosidases (alpha- or beta-galactosidase, neuraminidase), indicated that sialic acid and alpha-linked galactose were in terminal positions, beta-galactosyl residues were internally located, and chains containing the sequence sialic acid-N-acetylgalactosamine were present.
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PMID:Isolation and characterization of three major glycoproteins from thyroid plasma membranes. 677 52

Sepharose 4B-immobilized desialylated ovine submaxillary mucin was used as an acceptor for galactose transfer from UDP-galactose, catalyzed by a Triton X-100-solubilized galactosyltransferase from human erythrocyte ghosts. The product could be cleaved from the insoluble acceptor substrate by alkaline borohydride treatment and identified on Bio-Gel P-2 as a disaccharide. The nature of the glycosidic bond of the isolated material was elucidated by periodate oxidation/NaB[3H]4 reduction/acid hydrolysis and subsequent identification of the aminopolyol formed as L-threosaminitol. Specific cleavage of the enzymatic product by beta-galactosidase indicated a beta-configuration for incorporated galactose. These data permit classification of the enzyme as UDP-galactose: alpha-D-N-acetylgalactosaminyl-protein beta (1 leads to 3) transferase. Furthermore, in the presence of Triton X-100, the enzyme from normal erythrocytes catalyzed transfer of galactose to the glycan moieties of asialo-agalacto-glycophorin in Tn-erythrocytes from a patient with permanent mixed-field polyagglutinability.
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PMID:Identification of the product formed by human erythrocyte galactosyltransferase. 678 80

Among the seven oligosaccharide fractions obtained by Bio-Gel P-4 column chromatography of urine of GM1-gangliosidosis Type 1 patients, three fractions (peaks V, VI, and VII) were completely missing in the urine of GM1-gangliosidosis Type 2 patients. Structural study of these oligosaccharide fractions by sequential exoglycosidase digestion in combination with methylation analysis and periodate oxidation has shown that peaks V, VI, and VII are mixtures of 16, 30, and 49 isomeric oligosaccharides. All these 95 oligosaccharides contain Gal beta 1 leads to 4GlcNAc beta 1 lead to 3 repeating structures in their outer chain moieties, indicating that the tissues of GM1-gangliosidosis Type 2 patients do contain beta-galactosidase activity which releases readily galactose residue from such repeating sugar chains.
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PMID:Urinary oligosaccharides of GM1-gangliosidosis. Structures of oligosaccharides excreted in the urine of type 1 but not in the urine of type 2 patients. 679 May 42

Swainsonine, an indolizidine alkaloid, inhibits the alpha-mannosidase that is involved in glycoprotein processing. Thus, in cultured animal cells, this alkaloid causes an increase in the surface content of high mannose glycoproteins and a decrease in the amount of complex type glycoproteins (Elbein, A. D., Solf, R., Dorling, P. R., and Vosbeck, K. (1982) Proc. Natl. Acad. Sci. U. S. A., 78, 7393-7397). In this report, the effect of swainsonine on the synthesis virus hemagglutinins was examined. Primary calf kidney cultures were infected with influenza virus and viral replication was allowed to proceed in the absence or presence of swainsonine. Several hours after the addition of swainsonine, [2-3H]mannose or [6-3H]glucosamine were added to label the hemagglutinins and the mature virus particles were isolated. Virus particles raised in the presence of this alkaloid had the same infectivity and hemagglutination titer as virus particles from control cells. However, when the hemagglutinins were examined on sodium dodecyl sulfate gels, the major hemagglutinin (HA0) and its subunits, HA1 and HA2, from swainsonine-treated cells, migrated faster, indicating that they were of lower molecular weights. The labeled hemagglutinins were digested with pronase and the resulting glycopeptides were chromatographed on Bio-Gel P-4. Both the mannose-labeled and glucosamine-labeled glycopeptides from swainsonine-treated virus migrated more slowly on these columns than those of controls cells, suggesting that they were altered in structure. Furthermore, when the glycopeptides were digested with endoglucosaminidase H, 90% of the glycopeptides from swainsonine-treated cells were susceptible to this enzyme, whereas only 30% of those from control cells were digested. The major oligosaccharide released from inhibited cells by endoglucosaminidase H was digestible with alpha-mannosidase, whereas that of control cells was resistant to this enzyme. However, the control cell glycopeptide was digested by a combination of neuraminidase, beta-galactosidase, beta-N-acetylhexosaminidase, and alpha-mannosidase. These data show that swainsonine prevents the formation of complex glycoproteins and gives rise to increased amounts of high-mannose glycoproteins.
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PMID:Swainsonine prevents the processing of the oligosaccharide chains of influenza virus hemagglutinin. 679 7

1. A method is described for following continuously the action of beta-galactosidase on 4-methylumbelliferyl beta-D-galactoside at pH 4.5, in which 4-methylumbelliferone production is measured at fluorescence excitation and emission wavelengths of 324 and 444nm respectively. 2. Initial-rate studies show that the presence of salt activates beta-galactosidase up to 100 mM, but is inhibitory above that concentration. The enzyme is very unstable at 37 degrees C and low ionic strength, but stability increases with ionic strength. 3. The stability of the enzyme at 37 degrees C decreases markedly with rising pH in the range 5.9--8.0. 4. Gel-filtration patterns demonstrate that there is a marked tendency to polymerization with increasing ionic strength. The gel-filtration pattern shows decreasing amounts of dimer with increasing pH. 5. The correlation between activity, stability and molecular form of beta-galactosidase is discussed. It is suggested that the dimeric form of the enzyme is the most stable and active form. The implications of this finding for the assay of beta-galactosidase under physiological conditions for prenatal diagnosis are discussed. 6. Evidence for the possible occurrence of a 36 000-mol.wt. from of beta-galactosidase is presented. 7. A computer program for the calculation of initial rates has been deposited as Supplementary Publication SUP 50114 (4 pages) at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1981) 193, 5.
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PMID:The stability and aggregation properties of human liver acid beta-D-galactosidase. 730 60

The activity of acid phosphatase (E.C.3.1.3.2.), arylsulfatase (E.C.3.1.1.23.), beta-galactosidase (E.C.3.1.1.23.), and beta-acetylglucosaminidase (E.C.3.2.1.30.) in rat liver homogenates of 4.5 month-old male rats is presented in this paper. The degradation processes are observed in rat liver homogenate after incubation. The activity of acid phosphatase and beta-acetylglucosaminidase increases, the activity in one of beta-galactosidase is constant, and arylsulfatase decreases during the time of incubation. Furthermore, the maxima of the enzyme activities shift during the incubation in the time of a day. Gel filtration of acid phosphatase on the Sephadex G-150 Superfine and DEAE-cellulose columns determinate the mutual content of acid phosphatase subunits to isoenzymes I and II in various points of a day. The greatest content of acid phosphatase subunits versus both the isoenzymes content is at 02(24), and the greatest content of isoenzyme II versus the content of isoenzymes I appears at 07(12). From these data it is clear that the period of the isoenzyme II synthesis from the subunit amounts to 5 h, while 10 h are necessary to create the isoenzyme I originated from isoenzyme II. The comparison of acid phosphatase activity before and after the homogenate filtration on the Sephadex column indicates the increase of this enzyme activity after its separation from the other proteins and other components.
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PMID:Rhythmic changes of some lysosomal hydrolases activity from rat liver. Rhythmic changes of acid phosphatase synthesis. 730 16

A boiled extract acidified to pH 5.5 from the blood plasma of partially hepatectomized rats was treated with neuraminidase and injected i.p. into untreated rats. The DNA-synthesis of the liver cells showed a four-fold increase in comparison with controls. Extracts from the plasma of partially hepatectomized rats without neuraminidase treatment showed no increase in DNA-synthesis. Injections of boiled acid extracts from plasma of normal rats, however, showed no comparable differences before and after neuraminidase treatment. The activity of neuraminidase treated boiled, plasma extract is lost after treatment both with trypsin-chymotrypsin and with beta-galactosidase. Gel chrmoatography of the factor gave a molecular weight of about 38,000 D. The specific activity of the active extract after chromatography was raised by a factor of 300. According to affinity chromatography the factor was shown to be a glycoprotein containing N-Ac-glucosamine. The factor is inert with respect to the proliferation of spleen and kidney, i.e. it is organ specific. According to these results a regulatory system of hepatopoiesis is proposed.
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PMID:Evidence for and characterization of a liver cell proliferation factor from blood plasma of partially hepatectomized rats. 737 73


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