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 main polysaccharide component of the thickened cell walls in the storage parenchyma of Lupinus angustifolius L. cotyledons is a linear (1-->4)-beta-linked D-galactan, which is mobilised after germination (L. A. Crawshaw and J.S.G Reid, 1984, Planta 160, 449-454). The isolation from the germinated cotyledons of a beta-D-galactosidase or exo-(1-->4)-beta-D-galactanase with a high specificity for the lupin galactan is described. The enzyme, purified using diethylaminoethyl-cellulose, carboxymethyl-cellulose and affinity chromatography on lactose-agarose, gave two bands (major 60 kDa, minor 45 kDa) on sodium dodecyl sulphate-gel electrophoresis, and two similar bands on isoelectric focusing (major, pI 7.0, minor pI 6.7, both apparently possessing enzyme activity). The minor component cross-reacted with an antiserum raised against, and affinity-purified on, the major band. Both components had a common N-terminal sequence. The minor component was probably a degradation product of the major one. The enzyme had limited beta-galactosidase action, catalysing the hydrolysis of p-nitrophenyl-beta-D-galactopyranoside and (1-->4)- and (1-->6)-beta-linked galactobioses. Lactose [beta-D-galactopyranosyl-(1-->4)-D-glucose] was hydrolysed only very slowly and methyl-beta-D-galactopyranoside not at all. Lupin galactan was hydrolysed rapidly and extensively to galactose, whereas other cell-wall polysaccharides (xyloglucan and arabinogalactan) with terminal non-reducing beta-D-galactopyranosyl residues were not substrates. A linear (1-->4)-beta-linked galactopentaose was hydrolysed efficiently to the tetraose plus galactose, but further sequential removals of galactose to give the tetraose and lower homologues occurred more slowly. Galactose, gamma-galactonolactone and Cu+2 were inhibitory. No endo-beta-D-galactanase activity was detected in lupin cotyledonary extracts, whereas exo-galactanase activity varied pari passu with galactan mobilisation. Exo-galactanase protein was detected, by Western immunoblotting of cotyledon extracts, just before the activity could be assayed and then increased and decreased in step with the enzyme activity. The exo-galactanase is clearly a key enzyme in galactan mobilisation and may be the sole activity involved in depolymerising the dominant (1-->4)-beta-galactan component of the cell wall.
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PMID:Purification and properties of a novel beta-galactosidase or exo-(1-->4)-beta-D-galactanase from the cotyledons of germinated Lupinus angustifolius L. seeds. 776 18

The effects of residual catabolite repression and the importance of induction timing were determined for a temperature-sensitive (ts) GAL-regulated stable yeast expression system. The Saccharomyces cerevisiae strain employed carries a reg1 mutation inhibiting catabolite repression, and a ts mutation enabling induction of the regulated GAL promoters by a temperature shift to 35 degrees C. Despite the reg1 mutation and induction method, glucose depressed lacZ expression from a GAL1 promoter during batch culture. beta-Galactosidase specific activity was consistently lower at higher initial glucose concentrations in both SDC (semi-defined) and YPDa (complex) media; decreases of 18-36% were observed as glucose concentration was increased between 1, 3, 5, and 10 g l-1. However, the reductions in beta-galactosidase specific activity due to residual catabolite repression were more than balanced by substantial improvements in biomass yield at higher glucose levels. Therefore, productivity rose with increasing glucose concentration; in YPDa medium, increasing initial glucose from 1 to 10 g l-1 resulted in a 2.6-fold increase in beta-galactosidase volumetric activity. Due to the negative effects of shifting temperature to 35 degrees C, the trade-offs between optimum growth and a lengthy induction period were also evaluated. Delaying the time of induction reduced final specific activities but improved cell yield, and waiting 14 h into batch culture to induce lacZ expression provided modest 9-15% improvements in overall productivity.
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PMID:Catabolite repression and induction time effects for a temperature-sensitive GAL-regulated yeast expression system. 776 17

Previous work has shown that N-terminal deletions of yeast histone H3 cause a 2- to 4-fold increase in the induction of GAL1 and a number of other genes involved in galactose metabolism. In contrast, deletions at the H4 N terminus cause a 10- to 20-fold decrease in the induction of these same GAL genes. However, H3 and H4 N-terminal deletions each decrease PHO5 induction only 2- to 4-fold. To define the GAL1 gene regulatory elements through which the histone N termini activate or repress transcription, fusions were made between GAL1 and PHO5 promoter elements attached to a beta-galactosidase reporter gene. We show here that GAL1 hyperactivation caused by the H3 N-terminal deletion delta 4-15 is linked to the upstream activation sequence. Conversely, the relative decrease in GAL1 induction caused by the H4N-terminal deletion delta 4-28 is linked to the downstream promoter which contains the TATA element. These data indicate that the H3 N terminus is required for the repression of the GAL1 upstream element, whereas the H4N terminus is required for the activation of the GAL1 downstream promoter element.
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PMID:Yeast histone H3 and H4 N termini function through different GAL1 regulatory elements to repress and activate transcription. 777 66

A method is described for the detection of Escherichia coli beta-galactosidase-expressing leukemic cells in ex vivo bone marrow samples. 4-Methylumbelliferyl-beta-D-galactopyranoside is used as a substrate in a kinetic assay. D-Galactose is used to suppress endogenous lysosomal beta-galactosidase activity, yielding a sixfold increase in sensitivity. With this assay, the detection limit is one leukemic cell per 10(4) normal bone marrow cells.
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PMID:Differential suppression of background mammalian lysosomal beta-galactosidase increases the detection sensitivity of LacZ-marked leukemic cells. 786 72

Human lysosomal beta-galactosidase is organized as a 680-kDa complex with cathepsin A (also named carboxypeptidase L and protective protein), which is necessary to protect beta-galactosidase from intralysosomal proteolysis. To understand the molecular mechanism of beta-galactosidase protection by cathepsin A, we defined the structural organization of their complex including the beta-galactosidase-binding interface on cathepsin A. Radiation inactivation analysis suggested the existence of a 168-kDa structural subunit of the complex containing both beta-galactosidase and cathepsin A. Chemical cross-linking of the complex confirmed the existence of this subunit and showed that it is composed of one cathepsin A dimer and one beta-galactosidase monomer. The modeling of the cathepsin A dimer tertiary structure based on atomic coordinates of a wheat carboxypeptidase suggested a putative beta-galactosidase-binding cavity formed by the association of two cathepsin A monomers. According to this model two exposed loops of cathepsin A bordering the cavity were chosen as part of a putative beta-galactosidase-binding interface. Synthetic peptides corresponding to these loops were found both to dissociate the complex and to inhibit its in vitro reconstitution from purified cathepsin A and beta-galactosidase. The defined location of the GAL monomer in the complex with 35% of its surface covered by the CathA dimer may explain the stabilizing effect of CathA on GAL in lysosome.
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PMID:Human lysosomal beta-galactosidase-cathepsin A complex: definition of the beta-galactosidase-binding interface on cathepsin A. 787 22

The early renal function parameters (RFP), i.e. urinary alanine aminopeptidase (AAP), beta-galactosidase (beta GAL), N-acetyl-beta-D-glucosaminidase (NAG), retinol-binding protein (RBP), albumin (ALB), total protein (TP) and the conventional RFP plasma creatinine were assessed in 8 patients before and during treatment with the nephrotoxic antitumor agent cis-platin. Plasma creatinine increased during treatment with cis-platin. In all patients, acute tubular damage was revealed by early RFP. Albumin and total protein excretion patterns suggested alterations in glomerular function. The cumulative change in RBP excretion was related to plasma creatinine concentrations following cis-platin administration. The present study demonstrates that urinary RBP is a valuable parameter for the early assessment of cis-platin-induced nephrotoxicity.
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PMID:Comparison of renal function parameters in the assessment of cis-platin induced nephrotoxicity. 791 Jun 67

The 67-kD elastin-binding protein (EBP) mediates cell adhesion to elastin and elastin fiber assembly, and it is similar, if not identical, to the 67-kD enzymatically inactive, alternatively spliced beta-galactosidase. The latter contains an elastin binding domain (S-GAL) homologous both to the aorta EBP and to NH2-terminal sequences of serine proteinases (Hinek, A., M. Rabinovitch, F. W. Keeley, and J. Callahan. 1993. J. Clin. Invest. 91:1198-1205). We now confirm the functional importance of this homology by showing that elastolytic activity of a representative serine elastase, porcine pancreatic elastase, was prevented by an antibody (anti-S-GAL) and by competing with purified EBP or S-GAL peptide. Immunohistochemistry of adult aorta indicates that the EBP exists as a permanent component of mature elastic fibers. This observation, together with the in vitro studies, suggests that the EBP could protect insoluble elastin from extracellular proteolysis and contribute to the extraordinary stability of this protein. Double immunolabeling of fetal lamb aorta with anti-S-GAL and antitropoelastin antibodies demonstrated, under light and electron microscopy, intracellular colocalization of the proteins in smooth muscle cells (SMC). Incubation of SMC with galactosugars to dissociate tropoelastin from EBP caused intracellular aggregation of tropoelastin. A tropoelastin/EBP complex was extracted from SMC lysates by coimmunoprecipitation and cross-linking, and its functional significance was addressed by showing that its dissociation by galactosugars caused degradation of tropoelastin by endogenous serine proteinase(s). This suggests that the EBP may also serve as a "companion" to intracellular tropoelastin, protecting this highly hydrophobic protein from self-aggregation and proteolytic degradation.
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PMID:67-kD elastin-binding protein is a protective "companion" of extracellular insoluble elastin and intracellular tropoelastin. 803 52

Glucose metabolism and glucose-stimulated insulin secretion are thought to be controlled at the level of glucose phosphorylation in pancreatic islet beta-cells. In the current study we have investigated the importance of glucose phosphorylation by using recombinant adenovirus as a gene delivery system for isolated rat islets. Treatment of islets with a virus containing the cDNA encoding the Escherichia coli beta-galactosidase gene (AdCMV-beta GAL) resulted in efficiencies of gene transfer of 70.3 +/- 2.5 and 61.2 +/- 2.2% in two independent experiments. Treatment of islets with a virus containing the cDNA encoding rat hexokinase I (AdCMV-HKI) resulted in a 10.7-fold increase in immunodetectable hexokinase protein and a similar increase in enzyme activity. A large percentage of the overexpressed hexokinase activity was associated with a cell fraction enriched in mitochondria. These changes in enzyme level were accompanied by a 2-fold increase in insulin release and [5-3H]glucose usage at basal glucose concentrations (3 mM). The rate of glucose usage at 20 mM glucose and the magnitude of the insulin secretory response to this stimulatory level of the sugar were unchanged relative to control islets. Overexpression of hexokinase I in isolated islets therefore creates a phenotype of elevated basal insulin release similar to that seen in islets from obese and insulin-resistant mammals. The discrepancy between the large increase in hexokinase activity and the small increase in glucose usage and insulin release may indicate, however, that other steps in glucose metabolism become rate-limiting after only modest increases in glucose-phosphorylating activity.
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PMID:Overexpression of hexokinase I in isolated islets of Langerhans via recombinant adenovirus. Enhancement of glucose metabolism and insulin secretion at basal but not stimulatory glucose levels. 806 45

Alterations in the metabolic functions of trabecular meshwork (TM) cells are thought to be involved in the pathogenesis of primary open-angle glaucoma (POAG). In an investigation of this possibility, 30 trabeculectomy specimens from patients with POAG were examined histochemically for 11 lysosomal and membrane-bound enzymes. The patients ranged from 48 to 87 years in age. The degree of enzyme staining was compared with that of 15 age-matched controls obtained from an eye bank at less than 24 h after death. There was no history of eye disease in the controls. The enzymes examined were: dipeptidylpeptidases II and IV (DPPII and IV); beta-glucuronidase (beta-GLUC); acid-beta-galactosidase (s beta-GAL); N-acetyl-beta-D-glucosaminidase (NAG); nonspecific esterase (UE); acid phosphatase (SP); alkaline phosphatase (ALP); gamma-glutamyltransferase (GGT); and aminopeptidase A and M (APA and APM). Evaluation of the specimens was performed by two observers and by computer-aided optic densitometry. Results showed increased staining of SP, UE, GGT and APM in the pathological specimens as compared with the controls. SP and UE indicate phagocytic activity, APM is involved in collagen turnover and GGT participates in both drug detoxification and the breakdown of glutathione in the gamma-glutamyl cycle. Our observations show different hydrolase activities in the TM cells of human glaucomatous eyes as compared with normal values, suggesting that such metabolic differences may be related to the pathogenesis of POAG.
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PMID:Increased hydrolase activities in the human trabecular meshwork of glaucomatous eyes. 809 35

We and others have previously shown that a 67-kD cell surface elastin/laminin-binding protein (EBP) is responsible for cell adhesion to elastin and laminin and for mediating the process of elastin fiber assembly, but the nature of this protein was unknown. In this report we provide evidence that a 67-kD catalytically inactive form of beta-galactosidase produced by alternative splicing demonstrates immunological and functional similarity and sequence homology to the 67-kD EBP, suggesting that the two might be the same. Antibody prepared to a synthetic peptide, N-Ac-GSPSAQDEASPL, corresponding to a frame-shift-generated sequence unique to the alternatively spliced form of human beta-galactosidase, also recognized sheep EBP both on Western blotting and in aortic tissue. Furthermore, this synthetic peptide (S-GAL) binds to elastin and laminin, but not to fibronectin, collagen I, or collagen III. Moreover, both tropoelastin and laminin which bind to S-GAL peptide affinity columns can be specifically eluted from them with an excess of free S-GAL peptides. In addition, sequence homology among this splice variant of human beta-galactosidase, sheep EBP, and NH2-terminal sequences of some elastases suggests that these proteins share a common ligand-binding motif that has not been previously recognized.
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PMID:The 67-kD elastin/laminin-binding protein is related to an enzymatically inactive, alternatively spliced form of beta-galactosidase. 838 99


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