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)

Isoelectric focusing was used to investigate the multiple forms of acid phosphatase, arylsulfatase, beta-glucuronidase, beta-galactosidase and beta-N-acetylhexosaminidase in the following, previously characterized subcellular fractions from rat kidney: a special rough microsomal fraction, enriched up to 9-fold over the homogenate in acid hydrolases; a smooth microsomal fraction; a Golgi membrane fraction enriched about 2.5-fold in acid hydrolases and 10- to 20-fold in several glycosyl transferases; and a lysosomal fraction enriched up to 25-fold in acid hydrolases. The electro-focusing behavior of the hydrolases in these fractions was markedly sensitive to the autolytic changes that occur under acidic conditions, even at 4 degrees C. Autolysis was minimized by extracting fractions in an alkaline medium (0.2% Triton X-100, 0.1 M sodium glycinate buffer, pH 10, 0.1 % p-nitrophenyloxamic acid) and adding p-nitrophenyloxamic acid (0.1 %), AN INHIBITOR OF LYSOSOMAL NEURAMINIDASE AND cathepsin D, to the pH gradient. The enzymes in the lysosomal fraction displayed a characteristic bimodal or trimodal distribution. Arylsulfatase, beta-glucuronidase and beta-N-acetylhexosaminidase occurred in an acidic form with an isoelectric point of 4.4, and a basic form with an isoelectric point of 6.2, 6.7 and 8.0, respectively. Acid phosphatase and beta-galactosidase occurred in an acidic, intermediate and basic form with isoelectric points of about 4. 1, 5.6 and 7.4, respectively. In the special rough microsomal fraction these enzymes were mostly in a basic form with isoelectric points between 7.5 and 9; these were 1-2 units higher than the corresponding basic forms in the lysosomal fraction. Treatment of extracts of the rough microsomal fraction with bacterial neuraminidase raised the isoelectric points of all five hydrolases by 1-2.5 units, indicating the presence of some N-acetylneuraminic acid residues in these basic glycoenzymes. The hydrolases in the Golgi fraction were largely in an acidic form with isoelectric points similar to or lower than those of the corresponding acidic components in the lysosomal fraction. The hydrolases in the smooth microsomal fraction showed isoelectric-focusing patterns intermediate between those in the rough microsomal and the Golgi fractions. These findings support the following scheme for the synthesis, transport and packaging of the lysosomal enzymes. Each hydrolase is synthesized in a restricted portion of the r
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PMID:Changes in electronegativity of lysosomal hydrolases during intracellular transport. An isoelectric-focusing study in subcellular fractions of rat kidney. 23 56

Beta-Galactosidase [EC 3.2.1.23] has been purified from a culture of Aspergillus oryzae by 2-propanol fractionation, column chromatography on DEAE-Sephadex A-50 and Sephadex G-200. The preparation was homogeneous on ultracentrifugation and disc electrophoresis. The enzyme showed pH optima of 4.5 with ONPG-1 as a substrate and 4.8 with lactose as a substrate. The stable pH range was from 4.0 to 9.0 and the optimum temperature was 46 degrees. The Michaelis constants were 7.2 X 10-minus 4 M with ONPG and 1.8 X 10-minus 2 M with lactose. Hg-2+, Cu-2+, N-bromosuccinimide, and sodium laurylsulfate caused marked inhibition. The apparent molecular weight was calculated to be about 105,000 by Sephadex gel filtration and sucrose density gradient centrifugation.
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PMID:Purification and properties of beta-galactosidase from Aspergillus oryzae. 23 99

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

The parameters involved in the action of beta-galactosidase (EC 3.2.1.23) (Escherichia coli) on allolactose, the natural inducer of lac operon in E. coli, were studied. At low allolactose concentrations only galactose and glucose were formed, while at high allolactose concentrations transgalactolytic oligosaccharides were also produced. Detectable amounts of lactose were not formed. The V and Km values (49.6 U/mg and 0.00120 M, respectively) indicated that allolactose is as good if not a better substrate of beta-galactosidase as lactose. The pH optimum with allolactose (7.8-7.9) as well as its activation by K+ (as compared to activation by Na+) were similar to the case with lactose as substrate. The alpha-anomer of allolactose was hydrolyzed about two times as rapidly as was the beta-anomer.
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PMID:The action of beta-galactosidase (Escherichia coli) on allolactose. 24 75

Strains of Escherichia coli K-12 containing the colicin Ib (Col Ib) factor did not produce progeny phage when infected by T5 bacteriophage. The cells were killed but did not lyse. If sodium dodecyl sulfate (SDS) was added to T5-infected E. coli (Col Ib), lysis occurred prematurely, but no phage were produced. SDS had no effect on infected cells that did not contain the Col Ib factor or on uninfected cells with or without the Col Ib factor. Cells that contained a mutant Col Ib factor that allowed phage production were not prematurely lysed after infection in the presence of SDS. When the Col Ib-containing cells were infected, protein and RNA synthesis stopped at about 10 min postinfection, and the cells released abnormal amounts of 32P-containing material, ATP, and beta-galactosidase into the medium. They also became inhibited in their ability to accumulate thiomethyl-beta-D-galactopyranoside and to utilize glycerol. Two alternative hypotheses are presented to explain these results.
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PMID:Membrane damage in abortive infections of colicin Ib-containing Escherichia coli by bacteriophage T5. 32 28

Since environmental exposure to arsenicals has been correlated with a high skin cancer risk among populations exposed to sunlight, it is possible that arsenicals might interfere with the repair of damage to DNA (mostly thymine dimers) resulting from the ultraviolet rays in sunlight. To test this hypothesis, strains of E. coli, differing from each other only in one or more repair functions, were exposed to UV light and then plated in the presence or absence of sodium arsenite. Survival after irradiation of wild type E. coli (WP(2)) was significantly decreased by 0.5mM arsenite. This effect was also seen in strains which are unable to carry out excision repair, suggesting that arsenite inhibits one or more steps in the post-replication repair pathways. This is confirmed by the finding that arsenite has no effect on the post-irradiation survival of a recA mutant, which does not carry out post-replication repair. Mutagenesis after ultraviolet irradiation depends on the rec(+) and lex(+) genes. Arsenite decreases mutagenesis in strains containing these genes. In order to determine its mechanism of action, dose-response relationships of arsenite on a number of cellular functions were carried out. The most sensitive cellular functions found were the induction of beta-galactosidase and the synthesis of RNA. Since error-prone repair in E. coli is an inducible process, the inhibition of mutagenesis after UV irradiation may be the result of inhibition of messenger RNA synthesis.
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PMID:Effects of arsenite on DNA repair in Escherichia coli. 33 97

Escherichia coli Q13 was infected with bacteriophage Q beta and subjected to energy source shift-down (from glucose-minimal to succinate-minimal medium) 20 min after infection. Production of progeny phage was about fourfold slower in down-shifted cultures than in the cultures in glucose medium. Shift-down did not affect the rate of phage RNA replication, as measured by the rate of incorporation of [14C]uracil in the presence of rifampin, with appropriate correction for the reduced entry of exogenous uracil into the UTP pool. Phage coat protein synthesis was three- to sixfold slower in down-shifted cells than in exponentially growing cells, as determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The polypeptide chain propagation rate in infected cells was unaffected by the down-shift. Thus, the reduced production of progeny phage in down-shifted cells appears to result from control of phage protein synthesis at the level of initiation of translation. The reduction in the rate of Q beta coat protein synthesis is comparable to the previously described reduction in the rate of synthesis of total E. coli protein and of beta-galactosidase, implying that the mechanism which inhibits translation in down-shifted cells is neither messenger specific nor specific for 5' proximal cistrons. The intracellular ATP pool size was nearly constant after shift-down; general energy depletion is thus not a predominant factor. The GTP pool, by contrast, declined by about 40%. Also, ppGpp did not accumulate in down-shifted, infected cells in the presence of rifampin, indicating that ppGpp is not the primary effector of this translational inhibition.
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PMID:Control of protein synthesis in Escherichia coli: control of bacteriophage Q beta coat protein synthesis after energy source shift-down. 38 18

The effect of lysosomotropic agent--sodium aurothiomalate on liver damage and lysosomal changes during acute toxic hepatitis was studied. Combined administration of sodium aurothiomalete led to less extensive necrosis and to widening dystrophic areas in the hepatic parenchyma. Solubilization of the acid RNA-ase activity was decreased, and nonsedimentable activities of beta-galactosidase, cathepsin D were the same as in acute CCl4-hepatitis.
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PMID:[Effect of sodium aurothiomalate in acute toxic hepatitis]. 40 45

Carboxymethylated beta-galactosidase from Escherichia coli was dissociated at 100 degrees C to form carboxymethylated fragments A and B. The mol.wts. of carboxymethylated fragments A and B were determined by gel filtration to be 64300 and 22400 respectively. Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis of carboxymethylated fragments A and B that had been pretreated with 2-mercaptoethanol and sodium dodecyl sulphate yielded mol.wts. of 64000 and 22100 respectively. Carboxymethylated fragments A and B had arginine as their C-terminal amino acid. When a crude extract of E. coli M15 was filtered through a column of Sepharose 6B, it was found that carboxymethylated fragment B could restore beta-galactosidase activity when added to fractions having mol.wts. estimated to be 123000, 262000 and 506000. These fractions are referred to as ;complementable fractions'. Similarly, it was found that carboxymethylated fragment A could restore enzyme activity to tractions having mol.wts. estimated to be 63000, 253000 and 506000. Estimates of the molecular weights of the beta-galactosidase activity obtained by restoration with carboxymethylated fragments A and B were made by filtering the active enzyme through another column of Sepharose 6B. The enzyme obtained by complementation with carboxymethylated fragment B, i.e. the complemented enzyme, had mol.wt. 525000, and that obtained with carboxymethylated fragment A had mol.wts. of 525000, 646000 and 2000000. The latter finding suggests that multiple forms of complemented beta-galactosidase can exist.
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PMID:Restoration of beta-galactosidase to Escherichia coli M15. Complementation studies. 41 87

GM1-ganglioside hydrolysis by leukocytes and fibroblasts, tissues easily obtainable from patients, was investigated using 3H-labeled GM1 and was found to be at least as active as that reported for any other tissue. Sodium taurocholate was required for the reaction, the crude bile salt at an optimum concentration of 0.4% producing twice as much activity as pure taurocholate at its optimum concentration of 0.8%. Leukocyte GM1-ganglioside beta-galactosidase and 4-MU-beta-gal cleaving activities were similar, 134.5 +/- 23.3 and 179.8 +/- 25.4 nmol/h/mg protein, respectively. In cultured skin fibroblasts and amniotic fluid cells these enzyme activities were 4 to 5 times higher. Homozygotes for GM1-gangliosidosis showed negligible activity while in heterozygotes the leukocyte GM1-cleaving activity was reduced to one-third of control values. In leukocytes from patients with four other sphingolipid storage diseases the activity was either normal (Krabbe's, Tay-Sachs, Metachromatic leukodystrophy) or increased (adult Gaucher's).
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PMID:GM1-ganglioside beta-galactosidase in leukocytes and cultured fibroblasts. 41 12


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