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)

Incubation of UDP-GlcNAc and radiolabeled GlcNAc beta 1-3Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4GlcNAc (1) with human serum resulted in the formation of the branched hexasaccharide GlcNAc beta 1-3Gal beta 1-4GlcNAc beta 1-3(GlcNAc beta 1-6)Gal beta 1-4GlcNAc (2) in yields of up to 22.2%. The novel reaction represents midchain branching of the linear acceptor; the previously known branching reactions of oligo-(N-acetyllactosaminoglycans) involve the nonreducing end of the growing saccharide chains. The structure of 2 was established by use of appropriate isotopic isomers of it for degradative experiments. The hexasaccharide 2 was cleaved by an exhaustive treatment with jack bean beta-N-acetylhexosaminidase, liberating two GlcNAc units and the tetrasaccharide Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4GlcNAc (3). Endo-beta-galactosidase from Bacteroides fragilis cleaved 2 at one site only, yielding the disaccharide GlcNAc beta 1-3Gal (4) and the branched tetrasaccharide GlcNAc beta 1-3(GlcNAc beta 1-6)Gal beta 1-4GlcNAc (5). The structure of 5 was established by partial acid hydrolysis and subsequent identification of the disaccharide GlcNAc beta 1-6Gal (6), together with the trisaccharides GlcNAc beta 1-6Gal beta 1-4GlcNAc (7) and GlcNAc beta 1-3(GlcNAc beta 1-6)Gal (8) among the cleavage products. Galactosylation of 2 with bovine milk beta 1,4-galactosyltransferase and UDP-[6-3H]Gal gave the octasaccharide [6-3H]Gal beta 1-4GlcNAc beta 1-3 Gal beta 1-4GlcNAc beta 1-3([6-3H]-Gal beta 1-4GlcNAc beta 1-6)[U-14C] Gal beta 1-4GlcNAc (17), which could be cleaved with endo-beta-galactosidase into the trisaccharide [6-3H]Gal beta 1-4GlcNAc beta 1-3Gal (18) and the branched pentasaccharide GlcNAc beta 1-3-([6-3H]Gal beta 1-4GlcNAc beta 1-6) [U-14C]Gal beta 1-4GlcNAc (19). Partial hydrolysis of 2 with jack-bean beta-N-acetylhexosaminidase gave the linear pentasaccharide 1 and the branched pentasaccharide Gal beta 1-4GlcNAc beta 1-3(GlcNAc beta 1-6)Gal beta 1-4GlcNAc (20). The serum beta 1,6-GlcNAc transferase catalyzed also the formation of GlcNAc beta 1-3Gal beta 1-4GlcNAc beta 1-3(GlcNAc beta 1-6)Gal beta 1-4Glc (11) from UDP-GlcNAc and GlcNAc beta 1-3Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc (10). The pentasaccharide Gal alpha 1-3Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4GlcNAc (16), too, served as an acceptor for the enzyme.(ABSTRACT TRUNCATED AT 400 WORDS)
...
PMID:Human serum contains a novel beta 1,6-N-acetylglucosaminyltransferase activity that is involved in midchain branching of oligo (N-acetyllactosaminoglycans). 183 57

Clostridium thermosulfurogenes EM1 produced a thermostable (up to 70 degrees C) beta-galactosidase (beta Gal) with a pH optimum of 7 during growth on lactose. The gene (lacZ) encoding this enzyme was cloned and expressed in Escherichia coli using pUC18 as a vector. The nucleotide sequence of a 2.7-kb PstI fragment carrying the lacZ gene was determined. The open reading frame for lacZ, which encoded a protein of 716 amino acids with a calculated Mr of 83,728, was confirmed by the identity of its deduced aa sequence with the chemically determined N-terminal aa sequence of the purified beta Gal of C. thermosulfurogenes EM1. The structural gene was preceded by a possible promoter sequence, 5'-TTGTAG (-35), 5'-TAATAT (-10); and a ribosome-binding site, 5'-AGGAGG. The cloned beta Gal was found to be indistinguishable from the native enzyme. The Mr of the active beta Gal was 170,000, as determined by Superose 12HR gel filtration and gradient gel electrophoresis. This indicated that this enzyme is composed of two identical subunits. Comparison of the aa sequences of different beta Gal revealed that five large regions of similarity with the enzymes from E. coli (lacZ, ebgA), Klebsiella pneumoniae (lacZ), and Lactobacillus bulgaricus are present in the beta Gal of C. thermosulfurogenes EM1 and that the putative active site residues (Glu461 and Tyr503 in the E. coli lacZ-encoded beta Gal) are conserved (Glu389 and Tyr429). Therefore, the thermostable beta Gal of C. thermosulfurogenes EM1 is more closely related to the enzyme of E. coli than to the likewise thermostable one of Bacillus stearothermophilus.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Cloning and analysis of the beta-galactosidase-encoding gene from Clostridium thermosulfurogenes EM1. 184 May 42

Endo-beta-galactosidase (EC 3.2.1.103) of Bacteroides fragilis, at 250 mU ml-1, did not cleave the internal galactosidic linkage of the linear radiolabelled trisaccharide GlcNAc beta 1-6Gal beta 1-4GlcNAc, or those of tetrasaccharides Gal beta 1-4GlcNAc beta 1-6Gal beta 1-4GlcNAc and Gal beta 1-4GlcNAc beta 1-6Gal beta 1-4Glc. The isomeric glycans which contained the GlcNAc beta 1-3Gal beta 1-4GlcNAc/Glc sequence were readily cleaved.
...
PMID:Single mid-chain GlcNAc beta 1-6Gal beta 1-4R sequences of linear oligosaccharides are resistant to endo-beta-galactosidase of Bacteroides fragilis. 184 79

The peripheral blood of most normal individuals has been shown to contain T cells that respond to beta-galactosidase (beta-Gal), presumably as a result of natural priming. Three T cell clones (clones 1,2,4) specific for beta-Gal were isolated from peripheral blood mononuclear cells (PBMC) after pretreatment with leucine methyl ester (LeuOMe); a fourth clone from the same individual was isolated from untreated cells. All four clones were CD4+ CD8- alpha beta TcR+ and clone 1 was additionally shown to be cytotoxic. Epstein-Barr virus (EBV) transformed B cell lines were derived from LeuOMe-treated or untreated PBMC and used to study the efficiency of presentation of beta-Gal to one of the clones. The results indicated that B cells transformed after LeuOMe treatment presented beta-Gal at lower concentrations than untreated controls. beta-Gal would therefore appear to be a highly suitable model antigen for studies of immunoregulation in humans.
...
PMID:Human T cell responses to beta-galactosidase. 184 91

The human papillomavirus type 6 (HPV-6) E4 gene was expressed in Escherichia coli as a fusion protein with E. coli beta-galactosidase (E4-beta-Gal), and rabbit antibody against the E4-beta-Gal was prepared. By Western blotting with this antibody, we detected E4 gene products in six out of 18 condyloma acuminata specimens. In four specimens (C-1, C-13, C-14 and C-19), the E4 protein was found as a 10K/11K doublet, but in other specimens (C-8 and C-23), only the 11K protein was detected. By Southern blot analysis, it was found that C-13 harboured HPV-6 DNA but that C-1 and C-8 harboured HPV-11 DNA, indicating that the E4 proteins of HPV-6 and -11 have cross-reactive antigenicity. After incubation at 37 degrees C of the C-23 tissue specimen, the 10K protein was clearly detected. These results suggest that the 10K protein may be derived from the 11K protein by a modification such as proteolytic cleavage before and/or after specimens were taken.
...
PMID:Human papillomavirus type 6 and 11 E4 gene products in condyloma acuminata. 184 5

A gene library for Clostridium acetobutylicum NCIB 2951 was constructed in the broad-host-range cosmid pLAFR1, and cosmids containing the beta-galactosidase gene were isolated by direct selection for enzyme activity on X-Gal (5-bromo-4-chloro-3-indolyl-beta-D-galactoside) plates after conjugal transfer of the library to a lac deletion derivative of Escherichia coli. Analysis of various pSUP202 subclones of the lac cosmids on X-Gal plates localized the beta-galactosidase gene to a 5.1-kb EcoRI fragment. Expression of the Clostridium beta-galactosidase gene in E. coli was not subject to glucose repression. By using transposon Tn5 mutagenesis, two gene loci, cbgA (locus I) and cbgR (locus II), were identified as necessary for beta-galactosidase expression in E. coli. DNA sequence analysis of the entire 5.1-kb fragment identified open reading frames of 2,691 and 303 bp, corresponding to locus I and locus II, respectively, and in addition a third truncated open reading frame of 825 bp. The predicted gene product of locus I, CbgA (molecular size, 105 kDa), showed extensive amino acid sequence homology with E. coli LacZ, E. coli EbgA, and Klebsiella pneumoniae LacZ and was in agreement with the size of a polypeptide synthesized in maxicells containing the cloned 5.1-kb fragment. The predicted gene product of locus II, CbgR (molecular size, 11 kDa) shares no significant homology with any other sequence in the current DNA and protein sequence data bases, but Tn5 insertions in this gene prevent the synthesis of CbgA. Complementation experiments indicate that the gene product of cbgR is required in cis with cbgA for expression of beta-galactosidase in E. coli.
...
PMID:Expression and nucleotide sequence of the Clostridium acetobutylicum beta-galactosidase gene cloned in Escherichia coli. 185 Jul 29

Different concentrations of ionic and non-ionic detergents were examined for optimization of the in vitro degradations of intestinal glycosphingolipids by alpha- and beta-glycosidases from human fecal bacteria. In 5 mM Triton X-100 the enzymes hydrolyzed glycosphingolipids with lactoseries type 1 and 2 chains essentially to lactosylceramide (LacCer). In 5 mM sodium di- and trihydroxy bile salts lactosylceramide was degraded to glycosylceramide (GlcCer) in varying extent by enzymes from all five strains. The minimal bile salt concentrations for optimal 1,4-beta-galactosidase activities varied between 1 and 20 mM, i.e., close to or above the critical micellar concentrations (cmc). Dihydroxy bile salts were the most efficient in promoting conversion of LacCer to GlcCer at concentrations below 10 mM and conjugation with a taurine residue did not markedly lower the GlcCer yield. The optimal detergent concentrations for hydrolyses of the p-nitrophenyl (pnp) glycosides Gal beta 1-pnp and GalNAc alpha 1-pnp were approximately 0.05 mM for Triton X-100 and 0.5 mM for sodium taurodeoxycholate, i.e., clearly below their reported cmc values. Galabiosylceramide, globotria- and globotetraosylceramides, not degraded in the Triton X-100 micelles, were also resistant to hydrolysis using the sodium bile salts as detergents. In contrast, lactotetraosylceramide and isoglobotriaosylceramide were significantly more degraded by enzymes from a Ruminococcus gnavus strain and gangliotetraosylceramide by enzymes from a Bifidobacterium bifidum and a Bifidobacterium infantis strain using bile salt detergents. All strains but R. gnavus released terminal GalNAc from para-Forssman but not from the globotetraosylceramide or Forssman structures using 5 mM sodium deoxycholate as detergent. GM1 desialylation by two Ruminococcus torques strains and the R. gnavus and B. bifidum strains were enhanced under identical conditions. We conclude that the observed effects on glycosphingolipid hydrolyses reflects variations in the micellar presentation of the substrates. In addition, detergents seem to have a direct stimulating effect on the glycosidases, however at concentrations 10-100-times below the ones optimal for glycolipid degradations. These results with optimized bile salt concentrations, further support our previous observations that these five fecal bacterial strains produce enzymes with selected specificities towards glycosphingolipid core chains of the lactoseries type 1 and 2.
...
PMID:Enhancing effects of bile salts on the degradation of glycosphingolipids by glycosidases from bacteria of the human fecal flora. 185 98

We have cloned the gene encoding the Mycoplasma pneumoniae cytadherence-accessory protein HMW3 into Escherichia coli to study its phase-variable expression. A truncated HMW3 protein (HMW3'; 113 kDa), identified using HMW3-specific, affinity-purified antibodies, was expressed under the control of the lacZ promoter in lambda gt11. The protein did not react with beta-galactosidase (beta Gal)-specific antibodies, however, indicating that HMW3' was not a beta Gal fusion protein. The direction of transcription was determined by examining gene expression from inserts in opposite orientations with respect to the lacZpo in pUC18 and pUC19, to generate pKV5 and pKV6. Amino acid sequence data were obtained from an enzymatically generated HMW3 peptide fragment and used to create a degenerate 17-mer probe. The degenerate 17-mer hybridized to the mycoplasma DNA insert in pKV6; both the 17-mer and the pKV6 insert hybridized to a 9.4-kb EcoRI fragment from wild-type (wt) M. pneumoniae chromosomal DNA. This EcoRI fragment was cloned from wt M. pneumoniae and an HMW3-deficient variant in both orientations into pUC18. The HMW3'-encoding region was localized to the center of the 9.4-kb EcoRI fragment, and no differences were observed in restriction patterns between the wt and variant. Although the 9.4-kb EcoRI fragment included the DNA segment encoding HMW3', neither this protein, nor derivatives thereof, were detected in IPTG-induced E. coli containing the EcoRI fragment from either wt or variant M. pneumoniae, in either orientation in pUC18.
...
PMID:Cloning and analysis of the gene encoding the cytadherence phase-variable protein HMW3 from Mycoplasma pneumoniae. 189 47

The presence and subcellular localization of UDP-Gal:glucosylceramide beta 1----4galactosyltransferase (GalT-2) was investigated in rat liver. For this purpose, purified Golgi apparatus, endoplasmic reticulum, and plasma membrane fractions were prepared from the liver and used as the enzyme source for detecting GalT-2. A pure Golgi apparatus, highly enriched in many glycosyltransferases, was the only fraction where GalT-2 was measurable. The reaction product formation rate under appropriate assay conditions, which requires high detergent concentration and Mn2+, was low but comparable with that of other glycosyltransferases. The product formation was stimulated by exogenously added acceptor GlcCer, donor UDP-Gal, and Golgi protein. The reaction product was a single spot that was identified by chromatographic behavior, sensitivity to beta-galactosidase, and permethylation studies as Gal beta 1----4Glc beta 1----1'Cer (lactosylceramide). A metabolic experiment, performed by determining the glycosphingolipids which became radioactive in the above subcellular fractions prepared from the liver of animals treated with glucose-labeled glucosylceramide, further indicated that the in vivo glycosylation of glucosylceramide takes place in the Golgi apparatus.
...
PMID:Localization in the Golgi apparatus of rat liver UDP-Gal:glucosylceramide beta 1----4galactosyltransferase. 190 Apr 30

A eukaryotic expression vector was constructed in which the coding nucleotide sequences (ADA) of human adenosine deaminase (ADA) were fused in frame with the coding sequences of the bacterial gene lacZ encoding beta-galactosidase (beta Gal). This ADA::lacZ fusion gene was anticipated to encode a hybrid protein that has retained the biological functions of both proteins. Transfection of mammalian cells with the fusion gene resulted in the synthesis of both ADA and beta Gal. Cells expressing the gene could therefore be detected with the histochemical staining procedure that relies on the conversion of the indicator, XGal, by beta Gal. In addition, the transfected cells could be sorted on a fluorescence-activated cell sorter with the use of a vital staining procedure described for the selection of beta Gal-producing cells. Cell lines that harbored the fusion gene were tested for ADA overexpression by exposing them to the cytotoxic adenosine analog 9-beta-D-xylofuranosyl adenine (Xyl-A), in the presence of the ADA inhibitor deoxycoformycin (dCF). Resistance to Xyl-A/dCF was observed in the lines carrying ADA::lacZ and moreover, the fraction of cells that survived a stringent selection for ADA overexpression also exhibited significantly increased levels of beta Gal, which confirmed the direct linkage between ADA and lacZ expression. The use of this and other fusion genes might be useful in the development of gene-therapy protocols where they could help to meet the demand for versatile methods to detect and select cells with newly introduced genes.
...
PMID:Construction and expression of an adenosine deaminase::lacZ fusion gene. 190 22


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---