Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: KEGG:D03345 (beta-Galactosidase)
 434 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous histochemical and biochemical studies have documented the presence of carbohydrate-containing molecules in the retinal interphotoreceptor matrix (IPM). The lectin peanut agglutinin (PNA), which preferentially binds galactose-containing carbohydrates, especially galactose-galactosamine linkages, selectively labels cone photoreceptor-associated domains of the IPM ('cone matrix sheaths') in a variety of vertebrate retinas. In the studies described here, the nature of these PNA-binding components was investigated by monitoring the effects of proteolytic and glycosidic enzymes on binding of the lectin in the retina and IPM. All proteolytic enzymes tested cause a marked reduction in PNA-binding to cone matrix sheaths, suggesting that proteinaceous components are important to their organization. Exposure to O-glycanase, but not N-glycanase, markedly reduces binding of PNA to cone matrix sheaths indicating that O-linked oligosaccharides are probably responsible for its binding. Galactose oxidase treatment reduces PNA-binding throughout the retina and IPM, confirming that galactose moieties are involved in its binding. beta-Galactosidase (either before or after neuraminidase treatment) does not alter the pattern of PNA binding, suggesting that neither terminal nor penultimate beta-linked galactose residues constitute a major proportion of the lectin's binding sites in the retina. Neuraminidase treatment markedly increases the density and distribution of PNA binding throughout the retina and IPM, however, this effect appears to be, at least in part, the result of the binding of the lectin to neuraminidase molecules that become associated with tissue sections in addition to binding to carbohydrate groups unmasked by desialation. Exposure to chondroitinases causes disruption of the morphological integrity of cone matrix sheaths and slight diminution of PNA binding. Other enzymes acting on common constituents of extracellular matrices do not have similar effects. Taken together, these observations suggest that PNA-binding to cone matrix sheaths is due to the presence of glycoconjugates with galactose-containing, O-linked oligosaccharide chains.
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PMID:Enzymatic characterization of peanut agglutinin-binding components in the retinal interphotoreceptor matrix. 310 30

beta-Galactosidase from B. coagulans strain L4 is produced constitutively, has a mol. wt. of 4.3 x 10(5) and an optimal temperature of 55 degrees C. The optimal pH at 30 degrees C is 6.0 whereas at 55 degrees C it is 6.5. The energy of activation of enzyme activity is 41.9 kJ/mol (10 kcal/mol). No cations are required. The Km with ONPG as substrate is 4.2-5.6 mM and with lactose is 50 mM. The Ki for inhibition by galactose is 11.7-13.4 mM and for dextrose is 50 mM. Galactose inhibited competitively while dextrose inhibited noncompetitively. The purified and unprotected enzyme is 70% destroyed in 30 min at 55 degrees C whereas in the presence of 2 mg/ml of BSA 42% of the activity is destroyed in 30 min at 55 degrees C. An overall purification of 75.3-fold was achieved.
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PMID:Purification and characterization of beta-galactosidase from a strain of Bacillus coagulans. 678 81

beta-Galactosidase from Alternaria tenius was purified to homogeneity from the cultural fluid using acetone precipitation, ion-exchange chromatography on DEAE-cellulose, adsorption on hydroxylapatite and affinity chromatography on N-(beta-D-galactopyranosyl-thiocarbamoyl)-beta-aminocaproyl-AN-Sepharose 4B. The enzyme homogeneity was demonstrated by ultracentrifugation and polyacrylamide gel electrophoresis with SDS or without it. The specific activity of the homogeneous enzyme is 160 u. per mg of protein; mol. weight as determined by various methods is 142 000-176 000, pI = 4.6, temperature optimum is 60-65 degrees, pH optima for o-nitrophenyl-beta-D-galactopyranoside (o-NPG) and lactose are 3.8--4.4 and 3.6--4.8, respectively. The Km values for o-NPG and lactose are 0.21 . 10(-3) and 6.57 . 10-3 M, respectively. The enzyme is a glycoprotein and contains up to 30% of carbohydrates. EDTA and pCMB have no effect on the beta-galactosidase activity. Galactose acts as a competitive inhibitor, while glucose has no inhibiting effect on the enzyme activity.
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PMID:[Purification and properties of beta-galactosidase from Alternaria tenius]. 679 53

beta-Galactosidase catalyzed beta-galactosylation not only of a hydroxyl group but also of a thiol group in the condensation reaction of D-galactose and 2-mercaptoethanol. The thio-galactosylation product was confirmed as 2-hydroxyethyl S-beta-D-galactoside on the bases of fast atom bombardment mass spectrometry, infrared spectroscopy, and nuclear magnetic resonance spectorometry. Aspergillus oryzae beta-galactosidase hydrolyzed p-nitrophenyl S-beta-D-galactoside most rapidly among several beta-galactosidases and produced the thio-galactosylation product most efficiently. The Penicillim multicolor enzyme was as effective as the A. oryzae enzyme. However the enzymes from Escherichia coli, Saccharomyces fragilis, Kluyveromyces lactis, and Bacillus circulans galactosylated hydroxyl groups predominantly to produce O-galactoside. The thio-galactoside was synthesized most effectively at a 2-mercaptoethanol concentration of about 1.25 M. Galactose concentration at 0.8-2.8 M did not affect the synthetic yield of the thiogalactoside so greatly.
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PMID:Galactosylation of thiol group by beta-galactosidase. 1083 Apr 85

Using five different steps, beta-Galactosidase has been purified from kidney beans to apparent electrophoretic homogeneity with approximately 90-fold purification with a specific activity of 281 units mg-1 protein. A single band was observed in native PAGE. Activity staining of the native gel with 5-bromo 4-chloro 3-indoxyl beta-D-galactopyranoside (X-Gal) at pH 4.0 also produced a single band. Analytical gel filtration in Superdex G-75 revealed the molecular mass of the native protein to be approximately 75 kD. 10% SDS-PAGE under reducing conditions showed two subunits of molecular masses, 45 and 30 kD, respectively. Hence, beta-galactosidase from kidney beans is a heterodimer. A typical protein profile with lambda max at 280 nm was observed and A280/A260 ratio was 1.52. The N-terminal sequence of the 45 kD band showed 86% sequence homology with an Arabidopsis thaliana and 85% with Lycopersicon esculentum putative beta-galactosidase sequences. The Electrospray Mass Spectrometric analysis of this band also revealed a peptide fragment that had 90% sequence homology with an Arabidopsis thaliana putative beta-galactosidase sequence. The N-terminal sequencing of the 30 kD band as well as mass spectrometric analysis both by MALDI-TOF and ES MS revealed certain sequences that matched with phytohemagglutinin of kidney beans. The optimum pH of the enzyme was 4.0 and it hydrolysed o- and p-nitrophenyl beta-D galactopyranoside with a Km value of 0.63 mmol/L and 0.74 mmol/L, respectively. The energy of activation calculated from the Arrhenius equation was 14.8 kcal/mol enzyme site. The enzyme was found to be comparatively thermostable showing maximum activity at 67 degrees C. Thermal denaturation of the enzyme at 65 degrees C obeys single exponential decay with first order-rate constant 0.105 min-1. Galactose, a hydrolytic product of this enzyme was a competitive inhibitor with a Ki of 2.7 mmol/L.
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PMID:Purification and characterization of a thermostable beta-galactosidase from kidney beans (Phaseolus vulgaris L.) cv. PDR14. 1275 12

Galactose was the major non-cellulosic neutral sugar present in the cell walls of 'Mitchell' petunia (Petunia axillaris x P. axillaris x P. hybrida) flower petals. Over the 24 h period associated with flower opening, there was a doubling of the galactose content of polymers strongly associated with cellulose and insoluble in strong alkali ('residual' fraction). By two days after flower opening, the galactose content of both the residual fraction and a Na(2)CO(3)-soluble pectin-rich cell wall fraction had sharply decreased, and continued to decline as flowers began to wilt. In contrast, amounts of other neutral sugars showed little change over this time, and depolymerisation of pectins and hemicelluloses was barely detectable throughout petal development. Size exclusion chromatography of Na(2)CO(3)-soluble pectins showed that there was a loss of neutral sugar relative to uronic acid content, consistent with a substantial loss of galactose from rhamnogalacturonan-I-type pectin. beta-Galactosidase activity (EC 3.2.1.23) increased at bud opening, and remained high through to petal senescence. Two cDNAs encoding beta-galactosidase were isolated from a mixed stage petal library. Both deduced proteins are beta-galactosidases of Glycosyl Hydrolase Family 35, possessing lectin-like sugar-binding domains at their carboxyl terminus. PhBGAL1 was expressed at relatively high levels only during flower opening, while PhBGAL2 mRNA accumulation occurred at lower levels in mature and senescent petals. The data suggest that metabolism of cell wall-associated polymeric galactose is the major feature of both the opening and senescence of 'Mitchell' petunia flower petals.
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PMID:Galactose metabolism in cell walls of opening and senescing petunia petals. 1908 20