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)

L-Proline, which is accumulated by Escherichia coli during growth in media of high osmolality, also induces the synthesis of the enzyme degrading it to glutamate. To determine if proline catabolism is inhibited during osmotic stress, proline utilization and the formation of proline dehydrogenase were examined in varying concentrations of NaCl and sucrose. Although the specific growth rate of E. coli with proline as the sole nitrogen source diminished as the solute osmolality increased, a comparable reduction in growth rate occurred with ammonium as the primary nitrogen source. Proline catabolism, as measured in whole cells by the conversion of [14C]proline to [14C]glutamate, was only slightly inhibited by solute osmolalities up to 1.0 osmol/kg; more than 50% of the initial activity was still found at 2.0 osmol/kg. By contrast, the specific activity of proline dehydrogenase in bacteria grown in the presence of added solutes decreased to less than 20% of the control level. This reduction was related to a lower rate of synthesis, but was independent of genes currently known to be involved in osmoregulation or proline metabolism. The specific activities of tryptophanase, beta-galactosidase, and histidinol dehydrogenase were also reduced under similar growth conditions. These results indicate that while proline catabolism is not directly inhibited by high solute concentrations, prolonged exposure to osmotic stress leads to its reduction as part of a more general metabolic response.
...
PMID:Nonspecific inhibition of proline dehydrogenase synthesis in Escherichia coli during osmotic stress. 268 74

This is a kinetic assay for measuring K+ in serum, based on the activation of pyruvate kinase (EC 2.7.1.40) by K+. We eliminated interference from Na+ and NH4+ ions, which also activate this enzyme, by including Na+-binding and NH4+-consuming reagents in the reaction mixture. The assay was developed with and evaluated in the Cobas Fara centrifugal analyzer (and has been used in other kinetic analyzers). Within-run and between-run CVs were less than 1.4% and less than 1.6%, respectively. The reaction rate per millimole of K+ per liter (0.05 delta A/min) was more than double that of the reagent blank (0.02 delta A/min). Results correlated well with those by flame photometry, and interference from bilirubin, hemoglobin, lipids, heparin, and other cations was negligible. This method, in conjunction with a previous method we have reported in which beta-galactosidase is used for measuring Na+ in serum, offers a practical alternative to the use of ion-selective electrodes and flame photometry for measuring these clinically important monovalent cations in high-throughput or "stat" biochemical analyzers.
...
PMID:Enzymatic determination of potassium in serum. 272 Sep 76

The intracellular function of a specific protein to protect lysosomal beta-galactosidase and neuraminidase activities against proteases in human fibroblasts was studied. Beta-Galactosidase was purified from human placenta to different degrees; a preparation (A) contained also two concomitant proteins, and a highly purified preparation (B) contained only the mature beta-galactosidase. The protein concentrate of the culture medium of normal fibroblasts restored the activities of the deficient enzymes, beta-galactosidase and neuraminidase, in galactosialidosis cells. This effect was inhibited only by the anti-A anti-serum, and not by the anti-B antiserum. A 46-kilodalton protein, secreted from fibroblasts cultured in the presence of ammonium chloride, was detected again only by the anti-A antiserum, and not by the anti-B antiserum. It was concluded that this protein has a function to restore their activities in fibroblasts from galactosialidosis patients after being endocytosed from the culture medium.
...
PMID:Galactosialidosis: a direct evidence that a 46-kilodalton protein restores deficient enzyme activities in fibroblasts. 310 51

Methods for isolation and purification of beta-galactosidase from Bacillus subtilis, st. IBP-101 are described. The bacterial cells were disrupted by different procedures such as freezing and thawing with subsequent autolysis at 37 degrees C, disrupting in a French press DKM-3 or in ultrasonic disintegrators UZDN-1 (USSR) and Soniprep-150. It is shown that the specific activity and yield of the enzyme depends to a great extent on the disrupting procedure used. The best results were obtained in case of sonication. The preparation was purified by precipitation with ammonium sulphate (25-75% saturated) and chromatography on DEAE-cellulose and DEAE-Sephadex. The purified enzyme had a specific activity of 3155 units per mg protein. The molecular weight of the homogeneous according to gel polyacrylamide electrophoresis preparation was 215,000, as estimated by gel filtration, and 105,000, as estimated by SDS gel electrophoresis. The enzyme retains the activity in the presence of Na+, Mn2+ or Mg2+ ions or the thiolic reagents, dithiothreitol or 2-mercaptoethanol. The pH optimum of the enzyme activity is 6.3 and it is stable in water solutions at pH from 6 to 9 and can be lyophilized. The given preparation of beta-galactosidase has a high affinity for synthetic substrates such as o- and p-nitrophenyl-beta-D-galactopyranosides and 4-methylumbelliferyl-beta-D-galactopyranoside.
...
PMID:[Isolation of a highly active preparation of beta-D-galactosidase]. 311 62

Diplococcal beta-galactosidase, which is known to be useful for the structural studies of glycoprotein-linked oligosaccharides, was found to show the same substrate specificity in cleaving Gal beta 1-4 linkages of glycolipids as that of the oligosaccharides. The optimum conditions of beta-galactosidase in the 80% ammonium sulfate precipitates of the culture medium of Streptococcus (Diplococcus) pneumoniae were determined with nLcOse4Cer radiolabeled by the galactose oxidase-NaB3H4 procedure. Detergent was required for the highest activity, and different combinations of several buffers and detergents showed different properties in stimulating beta-galactosidase, and in enhancing or suppressing N-acetyl-beta-hexosaminidase which was contaminated in the enzyme preparation. The optimum pH was found to be at 6.5, and specific activity and Km were 8.1 nmol/mg protein/h and 1 nmol, respectively. While more than 70% of beta-galactose was liberated from LacCer and nLcOse4Cer within 1 h under the optimum conditions to form GlcCer and nLcOse3Cer, respectively, none was liberated from LcOse4Cer, GalCer, GgOse4Cer, GbOse3Cer, IV3 alpha GalnLcOse4Cer, and Il3NeuAcGgOse4Cer, showing the substrate specificity solely to Gal beta 1-4 linkage.
...
PMID:Diplococcal beta-galactosidase with a specificity reacting to beta 1-4 linkage but not to beta 1-3 linkage as a useful exoglycosidase for the structural elucidation of glycolipids. 312 98

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

Kinetics of Neutral red (NR) and Acridine orange (AO) uptake by cultured L cells (subline LSM) has been studied. It was found that the uptake of both NR and AO, with their constant concentrations in the medium was characterized as a two-phase process. During 2 hours, these cells concentrated as much as 90% of the total amount of NR and AO taken up during the whole incubation period. The segregation and accumulation of NR, AO as well as NH4Cl took place in lysosomes. NR and AO concentrations within the cells exceed by 600 and 400 times, respectively, those in the medium. NR, AO and NH4+ accumulation in cells resulted in inhibition of the activity of the following lysosomal hydrolases: cathepsins B and D, acid lipase, N-acetyl-beta,D-glucosaminidase, beta-galactosidase, acid phosphatase and galactosyltransferase, the latter being a marker of Golgi apparatus. The effect of lysosomal enzyme activity inhibition on the cell economy, and a possible role of lysosomotropic agents as regulators of the lysosomal apparatus functional activity are discussed.
...
PMID:[Effect of the segregation of neutral red, acridine orange and ammonium chloride by L cells (subline LSM) on lysosomal hydrolase activity]. 376 7

Lysosomal enzymes have been shown to be synthesized as microsomal precursors, which are processed to mature enzymes located in lysosomes. We examined the effect of ammonium chloride on the intracellular processing and secretion of two lysosomal enzymes, beta-glucuronidase and beta-galactosidase, in mouse macrophages. This lysosomotropic drug caused extensive secretion of both precursor and mature enzyme forms within a few hours, as documented by pulse radiolabeling and molecular weight analysis. The normal intracellular route for processing and secretion of precursor enzyme was altered in treated cells. A small percentage of each precursor was delivered to the lysosomal organelle slowly. Most precursor forms traversed the Golgi apparatus, underwent further processing of carbohydrate moieties, and were then secreted in a manner similar to secretory proteins. The lag time for secretion of newly synthesized beta-galactosidase precursor was notably longer than that for the beta-glucuronidase precursor. The source of the secreted mature enzyme was the lysosomal organelle. Macrophages from the pale ear mutant were markedly deficient in secretion of mature lysosomal enzyme but secreted precursor forms normally. These results suggest that ammonia-treated macrophages contain two distinct intracellular pathways for secretion of lysosomal enzymes and that a specific block in the release of lysosomal contents occurs in the pale ear mutant.
...
PMID:Effects of ammonia on processing and secretion of precursor and mature lysosomal enzyme from macrophages of normal and pale ear mice: evidence for two distinct pathways. 392 95

Mutants of Escherichia coli K-12 isolated for their ability to utilize gamma-aminobutyrate (GABA) as the sole source of nitrogen exhibit a concomitant several-fold increase in the activities of gamma-aminobutyrate-alpha-ketoglutarate transaminase (GSST, EC 2.6.1.19) and succinic semialdehyde dehydrogenase (SSDH, EC 1.2.1.16). The increase in rate of enzymatic activity is not accompanied by any changes in the affinities of the mutant enzymes for their respective substrates. The synthesis of the two enzymes is highly coordinate under a great variety of conditions, in spite of the wide range of activities observed. In cultures grown in minimal media with ammonium salts as the source of nitrogen, both GSST and SSDH are severely repressed by glucose. Substitution of ammonia with GABA, glutamate, or aspartate greatly reduces the effect of glucose on the synthesis of the GABA utilization enzymes. This escape from catabolite repression is specific for GSST and SSDH and does not involve other enzymes sensitive to catabolite repression (e.g., beta-galactosidase, EC 3.2.1.23, and aspartase, EC 4.3.1.1).
...
PMID:Control of the pathway of -aminobutyrate breakdown in Escherichia coli K-12. 455 85

Two merodiploids of Escherichia coli that contain genes for the lac operon on both chromosome and episome were tested for production of lac enzymes after growth on various carbon sources. The specific activity of beta-galactosidase (and of thiogalactoside transacetylase) was about twice that from haploid cells when grown on glycerol. With succinate as carbon source, the specific activity increased by an additional factor of 3. Up to 25% of the soluble cell protein is beta-galactosidase in these strains, one of which is inducible and the other constitutive. The enzyme is purified easily in high yield by ammonium sulfate fractionation and electrophoresis.
...
PMID:High-level production of -galactosidase by Escherichia coli merodiploids. 456 80


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

---