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)

beta-Galactosidase [EC 3.2.1.23] was isolated from a partially purified preparation obtained from cultured cells of a special strain of Aspergillus oryzae, RT 102 (FERM-P1680). The enzyme preparation gave a single protein band on polyacrylamide gel electrophoresis and was free from alpha-galactosidase, alpha- and beta-mannosidase, alpha- and beta-N-acetylhexosaminidase, and protease activities. The beta-galactosidase was capable of acting on aryl beta-galactosides, lactose, and lactosides. It also hydrolyzed beta-galactosyl linkages in urinary glycoasparagines and asialo alpha1-acid glycoprotein. The enzyme was rather stable in aqueous solution, retaining full activity at 4 degrees for at least several months. At pH 4.5, the optimum pH for the enzyme activity, and 37 degrees, full activity was maintained for several days.
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PMID:Characterization of beta-galactosidase from a special strain of Aspergillus oryzae. 1 18

Human factor VIII/von Willebrand factor protein containing 120 +/- 12 nmol of sialic acid and 135 +/- 13 nmol of galactose/mg of protein was digested with neuraminidase. The affinity of native factor VIII/von Willebrand factor and its asialo form for the hepatic lectin that specifically binds asialoglycoproteins was assessed from in vitro binding experiments. Native factor VIII/von Willebrand factor exhibited negligible affinity while binding of the asialo derivative was comparable to that observed for asialo-alpha1-acid glycoprotein. Incubation of asialo-factor VIII/von Willebrand factor with Streptococcus pneumoniae beta-galactosidase removed only 62% of the galactose but abolished binding to the purified hepatic lectin. When the asialo derivative was incubated with purified beta-D-galactoside alpha2 leads to 6 sialyltransferase and CMP-[14C]NeuAc, only 61% of the galactose incorporated [14C]NeuAc. From the known specificites of these enzymes, it is concluded that galactose residues important in lectin binding are present in a terminal Gal/beta1 leads to 4GlcNAc sequence on asialo-factor VIII/von Willebrand factor. The relative ristocetin-induced platelet aggregating activity of native, asialo-, and agalacto-factor VIII/von Willebrand factor was 100:38:12, respectively, while procoagulant activity was 100:100:103.
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PMID:Carbohydrate on human factor VIII/von Willebrand factor. Impairment of function by removal of specific galactose residues. 10 Apr 92

A simple procedure has been devised to isolate beta-galactosidase from jack bean meal. The final preparation gives one major protein banc in disc gel electrophoresis. The substrate specificity of this enzyme toward some natural oligosaccharides, glycoproteins, and sphingoglycolipids has been examined in detail. Among three isomers of N-acetyllactosamine, Galbeta1leads to4GlcNAc; while Galbeta1leads to3GlcNAc was hydrolyzed very slowly. This property can be used to distinguish the galactose linkage in asialo-GM1 (Galbeta1leads to3GalNAcbeta1leads to4Galbeta1leads to4Glcleads toCer) and that in lacto-N-neotetraosylceramide (Galbeta1leads to4GlcNAcbeta1leads to 3Galbeta1leads to4Glcleads toCer). For hydrolyzing glycolipids, the effect of sodium taurodeoxycholate and sodium taurochenodeoxycholate on the rate of hydrolysis was carefully examined. This enzyme hydrolyzes lactosylceramide and asialo-GM1 faster than GM1. These results suggest that in addition to the type and linkage of the penultimate sugar unit, the sugar unit at the distal position of the saccharide chain also affects the hydrolysis rate. It also readily liberates 80% D-galactosyl units from asialo alpha1-acid glycoprotein. Escherichia coli beta-galactosidase on the other hand cannot hydrolyze asialo-alpha1-acid glycoprotein, lactosylceramide, GM1, asialo-GM1, and lacto-N-neotetraosylceramide. The molecular weight of this enzyme is about 75,000 and the isoelectric point is pH 8.0. With p-nitrophenyl beta-D-galactopyranoside as substrate, optimal activity occurs at pH 2.8 with glycine-HCl buffer and at pH 3.5 with citrate-phosphate buffer. With lactose as substrate, the pH optimum in these two buffers are 2.8 and 4.0, respectively. Km values for p-nitrophenyl beta-D-galactopyranoside, o-nitrophenyl beta-D-galactopyranoside and lactose are 0.51 mM, 0.63 mM, and 12.23 mM, respectively. Many inhibitors for this enzyme including inorganic ions, monosaccharides, and glycosides are investigated. In contrast to E. coli beta-galactosidase, jack bean beta-galactosidase is not inhibited by p-aminophenyl thio-beta-D-galactopyranoside.
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PMID:Isolation and characterization of jack bean beta-galactosidase. 23 49

Complex carbohydrates on the surfaces of eukaryotic cells are thought to participate in a wide variety of cell-cell interactions. A model system has therefore been developed to study these processes. In the present experiments, the ability of chicken hepatocytes to recognize and adhere to sugars covalently linked to polyacrylamide gels was investigated. The gels were snythesized by two methods. Type I gels were prepared from a co-polymer of an active ester of acrylic acid (N-succinimidyl acrylate), acrylamide, and bisacrylamide. The "activated" polyacrylamide gel was then treated with the desired ligand containing an amino group, such as 6-aminohexyl O- or S-glycoside. Type II gels were formed by treating similar ligands with acryloyl chloride, followed by co-polymerization of the resulting N-substituted acrylamide with acrylamide and N,N'-methylenebisacrylamide. These polyacrylamide derivatives offer many advantages for studies with intact cells. They are not toxic to any cell type studied, can be cast in any desired shape, are transparent and stable over a wide range of pH values, and contain no cationic and low to negligible levels of anionic charge (charged groups can be introduced if desired), and the polyacrylamide matrix is stable to common biological agents such as bacteria and enzymes. In addition, type I gels can be synthesized using a broad range of molecules containing amino groups, such as glycopeptides, proteins, etc. The hepatocytes were prepared by collagenase perfusion of intact chicken livers. The rate and extent of adhesion of the cells to the derivatized gels was determined by measuring lactate dehydrogenase in these cells. This enzyme was also used to assay viability and cell "leakiness." At 37 degrees C, 70 to 100% of the cells adhered within 60 min to gels derivatized with N-acetylglucosamine, i.e. gels derivatized with 6-aminohexyl 2-acetamido-2-deoxy-beta-D-glucopyranoside (or the corresponding thioglycoside). By contrast, less than 5% of the cells adhered to polyacrylamide or to gels derivatized with 6-aminohexanol or the 6-aminohexyl glycosides of beta-D-glucose, beta-D-galactose, alpha-D-mannose, beta-D-maltose, beta-D-melibiose, beta-D-cellobiose, and (alpha or beta)-D-lactose. Kinetic studies with the chicken hepatocytes and N-acetylglucosamine gels showed that cell-gel binding was dependent upon Ca2+ and was decreased at low temperatures. Binding was inhibited by N-acetylglucosamine or by glycosides of this sugar, the most effective inhibitor being orosomucoid (alpha1-acid glycoprotein) pretreated with sialidase and beta-galactosidase. The cell surface receptor(s) involved in this interaction is not known, but may be related or identical to the chicken liver binding protein described by Lunney and Ashwell (Lunney, J., and Ashwell, G. (1976) Proc. Natl. Acad. Sci. U. S. A. 73, 341--343). The present results suggest that this model system should prove useful in delineating cell surface interactions with carbohydrates.
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PMID:Adhesion of chicken hepatocytes to polyacrylamide gels derivatized with N-acetylglucosamine. 70 Dec 94

Viridans streptococci have emerged as major opportunistic pathogens. We suggest that for these bacteria to proliferate in vivo and cause disease, they must utilize host tissue components. We have therefore examined the ability of all recognized species of viridans streptococci to liberate and utilize the constituent sugars of the glycans of the extensively sialylated human serum alpha1-acid glycoprotein (AGP) as the sole source of carbohydrate to support in vitro growth. Analysis of residual glycans following bacterial growth was performed by high-pH anion exchange chromatography with pulsed amperometric detection and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Only those species which produced sialidase-namely, Streptococcus oralis, S. intermedius, and S. defectivus--grew on AGP. The extent of degradation of glycans was dependent on the particular glycosidases produced by the bacteria. S. defectivus produced only a sialidase which released the terminal N-acetylneuraminic acid residues of the glycans, and the liberated sugar was utilized. S. intermedius also produced beta-galactosidase and beta-N-acetylglucosaminidase, which removed galactose and N-acetylglucosamine from desialylated glycans, all of which again were utilized by the organism. S. oralis produced beta-galactosidase, beta-N-acetylglucosaminidase, and alpha-fucosidase and novel alpha- and beta-mannosidases which were apparent only from the analysis of the residual sugars of AGP. S. oralis cleaved all the sugars from AGP except for 22% of the N-acetylglucosamine. The residual N-acetylglucosamine residues remaining were those linked to the asparagine of the peptide backbone. All the monosaccharides released by S. oralis from AGP, with the exception of fucose, were utilized. Sialidase production may be a key factor for growth of these species of viridans streptococci on glycoproteins in vivo, since they are commonly associated with extra-oral diseases, with S. oralis emerging as an important pathogen.
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PMID:Growth of Viridans streptococci on human serum alpha1-acid glycoprotein. 1040 65

Malignant transformation is often accompanied by an aberrant glycosylation profile of the cell surface-in particular, the production of GlcNAcbeta1-6Manalpha1 branches in N-linked glycoproteins. To identify the target glycoproteins, we show a method using recombinant chicken N-acetylglucosaminyltransferase VI (GnT VI) and radiolabeled uridine (5'-)diphosphate-GlcNAc. The assay exploits the fact that GnT VI has a strict requirement for the GlcNAcbeta1-6Manalpha1 structure for activity, when a pyridylaminated free N-glycan is used as the acceptor substrate. Human asialo-agalacto alpha1-acid glycoprotein (AGP), which is known to contain GlcNAcbeta1-6Manalpha1 branches in its N-linked glycan chains, was radiolabeled when reacted with GnT VI, whereas human asialo-agalacto transferrin and bovine fetuin, neither of which contains a GlcNAcbeta1-6Manalpha1 structure were not, thus corroborating the specificity of the assay. Several proteins from human serum after pretreatment with sialidase and beta-galactosidase could be detected using the assay. One was identified as AGP from its mobility on SDS-PAGE, demonstrating the potential of this assay even with crude materials. Furthermore, this method could detect a protein that was also positively stained with leukoagglutinating phytohemagglutinin (L(4)-PHA) using glycoproteins prepared from WiDr human colon cancer cells. This method should provide a useful complement to the current method, which relies on the specificity of L(4)-PHA.
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PMID:A specific detection of GlcNAcbeta1-6Manalpha1 branches in N-linked glycoproteins based on the specificity of N-acetylglucosaminyltransferase VI. 1642 2

Aberrant glycosylation on glycoproteins that are either presented on the surface or secreted by cancer cells is a potential source of disease biomarkers and provides insights into disease pathogenesis. N-Glycans of the total serum glycoproteins from advanced breast cancer patients and healthy individuals were sequenced by HPLC with fluorescence detection coupled with exoglycosidase digestions and mass spectrometry. We observed a significant increase in a trisialylated triantennary glycan containing alpha1,3-linked fucose which forms part of the sialyl Lewis x epitope. Following digestion of the total glycan pool with a combination of sialidase and beta-galactosidase, we segregated and quantified a digestion product, a monogalactosylated triantennary structure containing alpha1,3-linked fucose. We compared breast cancer patients and controls and detected a 2-fold increase in this glycan marker in patients. In 10 patients monitored longitudinally, we showed a positive correlation between this glycan marker and disease progression and also demonstrated its potential as a better indicator of metastasis compared to the currently used biomarkers, CA 15-3 and carcinoembryonic antigen (CEA). A pilot glycoproteomic study of advanced breast cancer serum highlighted acute-phase proteins alpha1-acid glycoprotein, alpha1-antichymotrypsin, and haptoglobin beta-chain as contributors to the increase in the glycan marker which, when quantified from each of these proteins, marked the onset of metastasis in advance of the CA 15-3 marker. These preliminary findings suggest that specific glycans and glycoforms of proteins may be candidates for improved markers in the monitoring of breast cancer progression.
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PMID:A strategy to reveal potential glycan markers from serum glycoproteins associated with breast cancer progression. 1881 22