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

---

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

A UDP-GlcNAc:R1-beta 1-3Gal(NAc)-R2 [GlcNAc to Gal(NAc)] beta 6-N-acetylglucosaminyltransferase activity from pig gastric mucosa microsomes catalyzes the formation of GlcNAc beta 1-3(GlcNAc beta 1-6)Gal-R from GlcNAc beta 1-3Gal-R where -R is -beta 1-3GalNAc-alpha-benzyl or -beta 1-3(GlcNAc beta 1-6)GalNAc-alpha-benzyl. This enzyme is therefore involved in the synthesis of the I antigenic determinant in mucin-type oligosaccharides. The enzyme also converts Gal beta 1-3Gal beta 1-4Glc to Gal beta 1-3(GlcNAc beta 1-6)Gal beta 1-4Glc. The enzyme was stimulated by Triton X-100 at concentrations between 0 and 0.2% and was inhibited by Triton X-100 at 0.5%. There is no requirement for Mn2+ and the enzyme activity is reduced to 65% in the presence of 10 mM EDTA. Enzyme products were purified and identified by proton NMR, methylation analysis and beta-galactosidase digestion. Competition studies suggest that this pig gastric mucosal beta 6-GlcNAc-transferase activity is due to the same enzyme that converts Gal beta 1-3GalNAc-R to mucin core 2, Gal beta 1-3(GlcNAc beta 1-6)GalNAc-R, and GlcNAc beta 1-3GalNAc-R to mucin core 4, GlcNAc beta 1-3(GlcNAc beta 1-6)GalNAc-R. Substrate specificity studies indicate that the enzyme attaches GlcNAc to either Gal or GalNAc in beta (1-6) linkage, provided these residues are substituted in beta (1-3) linkage by either GlcNAc or Gal. The insertion of a GlcNAc beta 1-3 residue into Gal beta 1-3GalNAc-R to form GlcNAc beta 1-3Gal beta 1-3GalNAc-R prevents insertion of GlcNAc into GalNAc. These studies establish several novel pathways in mucin-type oligosaccharide biosynthesis.
...
PMID:Mucin synthesis. Conversion of R1-beta 1-3Gal-R2 to R1-beta 1-3(GlcNAc beta 1-6)Gal-R2 and of R1-beta 1-3GalNAc-R2 to R1-beta 1-3(GlcNAc beta 1-6)GalNAc-R2 by a beta 6-N-acetylglucosaminyltransferase in pig gastric mucosa. 294 Dec 99

Preneoplastic mucosal changes were studied at six different time-points during dimethylhydrazine (DMH)-induced colorectal carcinogenesis in the rat. After 40 weeks of treatment, seven of 10 animals were bearing a total of 11 colorectal adenocarcinomas. The crypt cell production rate in the normal mucosa of DMH-treated animals was greatly increased in the left colon and rectum and further rose with the duration of the experiment. Focal disturbances of the mucosal architecture could be detected as early as 4 weeks after the initiation of DMH-treatment using a stereomicroscope. Their incidence was greatest in the left colon and rectum and increased strongly with the duration of carcinogen exposure. Characterization of these mucosal alterations, by means of conventional histology, morphometry after microdissection, cell kinetics, mucin histochemistry and quantitative enzyme histochemistry performed with serial sections, revealed mild epithelial dysplasia, a considerable elongation and dilatation of the crypts and a marked increase of the crypt cell production, including a shift of the main proliferative compartment from the basal to the medial crypt segment as well as the occurrence of mitotic figures in the luminal epithelium. In affected crypts, the goblet cells completely lacked sulphomucins and exclusively contained sialomucins. The activities of the enzymes diaminopeptidase IV (brush-border), succinate dehydrogenase (mitochondria) and acid beta-galactosidase (lysosomes) were markedly reduced. We conclude that these early mucosal alterations are indeed preneoplastic lesions and indicate the existence of the adenoma-carcinoma sequence in this animal model.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Characterization of stereomicroscopically identified preneoplastic lesions during dimethylhydrazine-induced colonic carcinogenesis. 314 93

The effects of a range of commercially available proteases and glycosidases on blastocyst development and hatching were examined on rabbit embryos cultured from the morula stage in a defined medium supplemented with charcoal-treated bovine serum albumin. The proteases tested were trypsin, alpha-chymotrypsin, thrombin, elastase, plasmin, papain, clostripain, collagenase, Streptomyces griseus protease and cathepsin C. The glycosidases tested were neuraminidase, alpha-mannosidase, beta-galactosidase and hyaluronidase. None of these enzymes appeared to stimulate blastocyst growth. The only enzymes which digested the embryonic investments, the zona and mucin coat, sufficiently to cause complete blastocyst hatching were trypsin and Streptomyces griseus protease at relatively low concentrations (250 ng/ml) and chymotrypsin and elastase at higher concentrations.
...
PMID:A survey of the effects of proteases and glycosidases on culture of rabbit morulae to blastocysts. 353 6

It was previously shown that reductive alkali treatment of purified human cervical mucin releases a heterogeneous population of reduced neutral, sialylated, and sulfated oligosaccharides (Yurewicz, E. C., and Moghissi, K. S. (1981) J. Biol. Chem. 256, 11895-11904). Four major sialylated oligosaccharide fractions were isolated with approximate compositions of Fuc:GlcNac:Gal:NeuAc:N-acetylgalactosaminitol (GalNAcol) = 0:0:0:1:1 (B1a), 0:0:1:1:1 (B2b), 0:1:2:1:1 (B3a), and 1:1:2:1:1 (B4a), where Fuc is fucose. They comprised roughly 3, 11, 7, and 6% of recovered oligosaccharide chains, respectively. On the basis of periodate oxidations, methylation analyses, and sequential degradations with glycosidases, the following structures were determined. (Formula: see text) Oligosaccharides 1 and 2 are characterized by the presence of N-acetylneuraminic acid in alpha 2,6-linkage to N-acetylgalactosaminitol. The remaining oligosaccharides contain N-acetylneuraminic acid in alpha 2,3-linkage to galactose residues. Oligosaccharides 3 and 4 and oligosaccharides 5 and 6 were isolated as unresolved isomeric mixtures in fractions B3a and B4a, respectively. Oligosaccharides 3 and 4 were distinguished on the basis of susceptibility to digestion with Aspergillus niger beta-galactosidase whereas oligosaccharides 5 and 6 were distinguished on the basis of differential rates of digestion with beef kidney alpha-fucosidase. The structural data indicate the presence of at least two sialyltransferases in human cervical epithelium and further suggest a potential physiologically significant competition between sialyltransferase and beta-N-acetylglucosaminyltransferase for C-6 of the N-acetylgalactosamine residue O-glycosidically linked to serine/threonine of the polypeptide core.
...
PMID:Structural studies of sialylated oligosaccharides of human midcycle cervical mucin. 355 66

A sialidase [EC 3.2.1.18] has been partially purified from human placenta by means of procedures comprising Con A-Sepharose adsorption, ammonium sulfate precipitation, sucrose density gradient centrifugation, and high-pressure liquid chromatography on a Shim pack Diol 300 column. On high-pressure liquid chromatography, most of the beta-galactosidase that comigrated with the sialidase on sucrose density gradient centrifugation was removed. The sialidase was purified 3,600-fold from the preparation obtained by Con A-Sepharose adsorption. The enzyme liberated the sialic acid residues from (alpha 2-3) and (alpha 2-6) sialyllactose, colomic acid, fetuin, and transferrin, but not from bovine submaxillary mucin. The enzyme also hydrolyzed gangliosides GM3, GD1a, and GD1b in the presence of sodium cholate as a detergent, but GM1 and GM2 were less susceptible to the enzyme. The optimum pHs for 4-methylumbelliferyl-N-acetylneuraminate, sialyllactose, fetuin, and GM3 lay between 4.0 and 5.0.
...
PMID:Human placental sialidase: partial purification and characterization. 365 92

The MAT-B1 and MAT-C1 ascites sublines of the 13762 rat mammary adenocarcinoma, which differ in several cell surface properties, contain a major mucin-type glycoprotein, termed ASGP-1. The sialic acid content of MAT-C1 ASGP-1 is 2-3-fold greater than MAT-B1 ASGP-1 (Sherblom, A. P., Buck, R. L., and Carraway, K. L. (1980) J. Biol. Chem. 255, 783-790). Sialic acid analysis demonstrated that, whereas MAT-C1 ASGP-1 contained approximately equal amounts of N-acetylneuraminic acid (NeuAc) and N-glycolylneuraminic acid (NeuGl), MAT-B1 ASGP-1 was devoid of NeuGl. MAT-B1 microsomes also did not contain NeuGl. MAT-B1 cells incubated with [3H]N-acetylmannosamine did not synthesize either labeled CMP-NeuGl or free NeuGl, even though the CMP-sialic acid synthetase was active with the substrate NeuGl. Thus, MAT-B1 cells may be deficient in the enzyme N-acetylneuraminate monooxygenase. The O-linked oligosaccharides from both MAT-B1 and MAT-C1 ASGP-1 have been shown to contain a core tetrasaccharide Gal(beta 1-4)GlcNAc(beta 1-6)(Gal(beta 1-3]GalNAc in which both galactose residues may be linked to additional sugars (Hull, S. R., Laine, R. A., Kaizu, T., Rodriquez, I., and Carraway, K. L. (1984) J. Biol. Chem. 259, 4866-4877). The distribution of NeuAc and NeuGl between the two galactose termini of the core tetrasaccharide was examined for MAT-C1 ASGP-1. Oligosaccharides were released by alkaline-borohydride treatment of MAT-C1 ASGP-1 which had been labeled with [14C]glucosamine and galactose oxidase/B3H4. Following fractionation by Bio-Gel P-4, DEAE-Sephadex, and high-performance liquid chromatography, oligosaccharides were analyzed for NeuAc and NeuGl and for susceptibility to digestion with beta-galactosidase. Three disialylated oligosaccharides were identified containing 2 mol of NeuAc (5.5% recovery), 2 mol of NeuGl (4.5%), or 1 mol each of NeuAc and NeuGl (11.1%). For monosialylated oligosaccharides, NeuGl appeared preferentially associated with the Gal(beta 1-4)GlcNAc terminus (9.0%), whereas significant amounts of oligosaccharide containing NeuAc at both the Gal(beta 1-3)GalNAc (2.6%) and Gal(beta 1-4)GlcNAc (4.5%) termini were detected. Each of the major qualitative differences between MAT-B1 and MAT-C1 oligosaccharides, including the presence of NeuGl (MAT-C1), sulfate (MAT-B1), and alpha-linked galactose (MAT-B1), occurs at the Gal(beta 1-4)GlcNAc terminus.
...
PMID:N-Acetylneuraminic acid and N-glycolylneuraminic acid in the O-linked oligosaccharides of a tumor cell glycoprotein. Incorporation and distribution. 391 40

Sialyl and galactosyl transferase activities are demonstrated in calf vitreous hyalocytes. For study of sialyl transferase activity, a partially purified vitreous preparation (collagen and hyaluronic acid removed), and bovine submaxillary mucin were treated with an insolubilized neuraminidase before use acceptor of radioactivity from CMP-[3H]-N-acetylneuraminic acid (CMP-[3H]-NAN). For study of galactosyl transferase activity the vitreous preparation was treated first with insolubilized neuraminidase and then with an insolubilized beta-galactosidase before use as acceptor of radioactivity from UDP-[3H]-galactose (UDP-[3H]-gal). Galactosyl transferase requires a divalent metal ion for optimal activity, and the reactions catalyzed by each enzyme are dependent upon pH, time of incubation and concentration of enzyme and/or acceptor.
...
PMID:Identification of sialyl and galactosyl transferase activities in calf vitreous hyalocytes. 609 99

In previous studies on glycosyltransferase activities in porcine trachea, we demonstrated the presence of two galactosyltransferases which transfer galactose from UDP-galactose to N-acetylglucosamine (Sheares, B.T. and Carlson, D.M. (1983) J. Biol. Chem. 258, 9893-9898). One enzyme, UDP-galactose:N-acetylglucosamine 3 beta-galactosyltransferase, synthesized galactosyl-beta 1,3-N-acetylglucosamine while the other, UDP-galactose:N-acetylglucosamine 4 beta-galactosyltransferase, synthesized galactosyl-beta 1,4-N-acetylglucosamine. A third galactosyltransferase has now been demonstrated utilizing a solubilized membrane preparation from pig trachea, which also synthesizes galactosyl-beta 1,4-N-acetylglucosamine as determined by gas-liquid chromatography and Diplococcus pneumoniae beta-galactosidase treatment. This new UDP-galactose:N-acetylglucosamine 4 beta-galactosyltransferase is distinct from the lactose synthetase A protein in that it does not bind to alpha-lactalbumin-agarose or to N-acetylglucosamine-agarose. The enzyme is separable from the UDP-galactose:N-acetylgalactosaminyl-mucin 3 beta-galactosyltransferase by affinity chromatography on asialo ovine submaxillary mucin adsorbed to DEAE-Sephacel. This newly discovered 4 beta-galactosyltransferase binds to UDP-hexanolamine-Sepharose and is partially separated from UDP-galactose:N-acetylglucosamine 3 beta-galactosyltransferase by Sephacryl S-200 gel filtration chromatography. Neither high concentrations of N-acetylglucosamine (200 mM) nor alpha-lactalbumin inhibits the incorporation of galactose into galactosyl-beta 1,4-N-acetylglucosamine by this enzyme.
...
PMID:Two distinct UDP-galactose: 2-acetamido-2-deoxy-D-glucose 4 beta-galactosyltransferases in porcine trachea. 642 38

A new procedure for inducing and purifying endo-beta-galactosidase from Escherichia freundii was described. The enzyme was found to be induced with high efficiency in culture medium containing Smith-degraded hog gastric mucin, which was prepared from a commercially available starting material. Endo-beta-galactosidase was then purified by ammonium sulfate fractionation, DEAE-Sephadex chromatography, and affinity chromatography on Sepharose conjugated with the Smith-degraded mucin. The enzyme thus purified by only three steps showed no other glycosidase or protease activities and had higher specific activity compared to the previous method. This new method has a great advantage since the gastric mucin is abundantly available and the efficiency of enzyme production was high without significant induction of exoglycosidase. The hydrolysis of oligosaccharides, glycosphingolipid, and keratansulfate was studied by using this newly purified enzyme. Kinetic data indicate that hydrolyzability of these substrates is largely affected by substrate concentration, enzyme concentration and the structure of substrates. Based on these results, the specificity of E. freundii endo-beta-galactosidase was discussed.
...
PMID:Purification and characterization of endo-beta-galactosidase from Escherichia freundii induced by hog gastric mucin. 678 49

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.
...
PMID:Identification of the product formed by human erythrocyte galactosyltransferase. 678 80


<< Previous 1 2 3 4 5 Next >>

---