Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this clinically useful enzyme immunoassay of digoxin in serum, we mix sample, beta-galactosidase-labeled digoxin, and anti-digoxin Fab fragments for 30 min at room temperature, then use Sepharose-bound second antibody for phase separation, and measure the unbound enzyme activity directly in the supernate of the equilibrium reaction mixture. The immunoassay buffer--phosphate-buffered isotonic saline with added rabbit globulin (4 g/L), hydrolyzed gelatin (2 g/L), Brij 96 detergent (5 g/L), glycerol (0.25 mol/L), and N-acetyl-8-anilinonaphthalene-1-sulfonic acid (2 mmol/L)--minimizes serum matrix effects for convenient measuring of unbound enzyme--digoxin conjugate. The immunoassay developed with Fab fragments has better displacement characteristics than that with intact antibody. Performance of the assay compares favorably with that of other manual digoxin immunoassays; in comparison studies with EMIT involving 110 clinical specimens, the coefficient of correlation was 0.97.
 ...
PMID:Competitive solid-phase enzyme immunoassay for measuring digoxin in serum. 351 90

Protein S, the most abundant protein synthesized during development of the fruiting bacterium Myxococcus xanthus, is coded by two highly homologous genes called protein S gene 1 (ops) and protein S gene 2 (tps). The expression of these genes was studied with fusions of the protein S genes to the lacZ gene of Escherichia coli. The gene fusions were constructed so that expression of beta-galactosidase activity was dependent on protein S gene regulatory sequences. Both the gene 1-lacZ fusion and the gene 2-lacZ fusion were expressed exclusively during fruiting body formation (development) in M. xanthus. However, distinct patterns of induction of fusion protein activity were observed for the two genes. Gene 2 fusion activity was detected early during development on an agar surface and could also be observed during nutritional downshift in dispersed liquid culture. Gene 1 fusion activity was not detected until much later in development and was not observed after downshift in liquid culture. The time of induction of gene 1 fusion activity was correlated with the onset of sporulation, and most of the activity was spore associated. This gene fusion was expressed during glycerol-induced sporulation when gene 2 fusion activity could not be detected. The protein S genes appear to be members of distinct regulatory classes of developmental genes in M. xanthus.
 ...
PMID:Differential expression of protein S genes during Myxococcus xanthus development. 391 84

The transport of proline is important for the adaptation of Salmonella typhimurium to osmotic stress because exogenous proline permits the growth of the organism in media of elevated osmotic strength that would otherwise be toxic. Measurements of the rate of [3H]proline transport in S. typhimurium indicated that the organism has two distinct proline permeases, the ProU and the ProP systems, whose activities increase more than fivefold as a consequence of growth in media containing 0.3 M NaCl or 0.47 M sucrose. Transport via a third proline permease, the PutP system, is not affected by the osmotic strength of the medium. We constructed strains that carry fusions of lacZ to proU or proP, genes that are required for the two osmotically stimulated proline transport systems. Assays of beta-galactosidase revealed that the transcription of the proU gene is increased more than 10-fold as a result of exposure of the cells to 0.3 M NaCl, 0.47 M sucrose, or equivalent concentrations of other solutes that are not freely diffusible across the cytoplasmic membrane. Increased transcription cannot be triggered by methanol, ethanol, and glycerol, substances that are freely diffusible across the membrane, suggesting that the signal for increased transcription might be an osmotic gradient across the cytoplasmic membrane. The proP gene does not show transcriptional regulation of sufficient magnitude to account for the stimulation of [3H]proline transport. Thus, the osmotic stimulation of the ProP system might be mediated by some posttranscriptional event.
 ...
PMID:Osmotic regulation of L-proline transport in Salmonella typhimurium. 392 95

The target size of four soluble enzymes (beta-galactosidase, pyruvate kinase, alcohol dehydrogenase, and glucose-6-phosphate dehydrogenase) in the presence or absence of subcellular membrane fractions has been determined by the radiation-inactivation method using samples in the frozen state. For each of the four enzymes, full activity was recovered after freezing and thawing in the absence of radiation. We found minimal (less than 20%) binding of the enzymes to either submitochondrial vesicles or sarcoplasmic reticulum vesicles. Under the conditions tested, beta-galactosidase, pyruvate kinase, and alcohol dehydrogenase exhibited target sizes which varied according to the experimental conditions, i.e., the buffer selected and also the presence or absence of membrane preparations. For these tetrameric enzymes, the target sizes were generally comparable to either a monomer or a dimer. By contrast, the target size of glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides was found to be essentially invariant when frozen in a variety of buffers and in the presence or absence of either cryoprotectant (sucrose or glycerol) or different membrane preparations. The target size from 19 separate determinations gave an average value of 104 +/- 16 kDa, which is comparable to the molecular weight of the enzyme (104 kDa). We conclude that glucose-6-phosphate dehydrogenase from L. mesenteroides is a reliable internal standard for radiation-inactivation studies of membrane preparations in the frozen state.
 ...
PMID:Glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides is a reliable internal standard for radiation-inactivation studies of membranes in the frozen state. 392 13

1. Both permanent and transient catabolite repression of beta-galactosidase synthesis in Escherichia coli are abolished by 5mm-3':5'-cyclic-AMP when elicited by glucose, but not when caused by a mixture of glucose, glucose 6-phosphate, gluconate and casein hydrolysate (casamino acids). 2. Glucose uptake is slightly increased by 3':5'-cyclic-AMP. 3. No significant effects of the nucleotide were found on the synthesis of protein and RNA, either in exponential growth on one substrate, or during a growth shift from glycerol to glycerol plus glucose. 4. Marked changes in the soluble-protein profiles of cells growing in glycerol and glucose were caused by the presence of 3':5'-cyclic-AMP. 5. Measurements of (14)CO(2) release from specifically-labelled glucose showed that 3':5'-cyclic-AMP greatly stimulated glycolytic activity while having a minor depressing effect on the metabolic flow through the pentose phosphate cycle. 6. The concentrations of several metabolic intermediates, particularly fructose 1,6-diphosphate, were greatly affected by the presence of 3':5'-cyclic-AMP. 7. Several metabolites partially relieved glucose repression of beta-galactosidase synthesis in EDTA-treated cells; three out of five of these metabolites reversed the effect more effectively than did 3':5'-cyclic-AMP. 8. The evidence for and against a direct role for 3':5'-cyclic-AMP is discussed. It is concluded that the evidence for indirect action is at least as strong as that for direct action.
 ...
PMID:Adenosine 3':5'-cyclic monophosphate and catabolite repression in Escherichia coli. 431 43

Catabolite repression of tryptophanase was studied in detail under various conditions in several strains of Escherichia coli and was compared with catabolite repression of beta-glactosidase. Induction of tryptophanase and beta-galactosidase in cultures grown with various carbon sources including succinate, glycerol, pyruvate, glucose, gluconate, and arabinose is affected differently by the various carbon sources. The extent of induction does not seem to be related to the growth rate of the culture permitted by the carbon source during the course of the experiment. In cultures grown with glycerol as carbon source, preinduced for beta-galactosidase or tryptophanase and made permeable by ethylenediaminetetraacetic acid (EDTA) treatment, catabolite repression of tryptophanase was not affected markedly by the addition of cAMP (3',5'-cyclic adenosine monophosphate). Catabolite repression by glucose was only partially relieved by the addition of cAMP. In contrast, under the same conditions, cAMP completely relieved catabolite repression of beta-galactosidase by either pyruvate or glucose. Under conditions of limited oxygen, induction of tryptophanase is sensitive to catabolite repression; under the same conditions, beta-galactosidase induction is not sensitive to catabolite repression. Induction of tryptophanase in cells grown with succinate as carbon source is sensitive to catabolite repression by glycerol and pyruvate as well as by glucose. Studies with a glycerol kinaseless mutant indicate that glycerol must be metabolized before it can cause catabolite repression. The EDTA treatment used to make the cells permeable to cAMP was found to affect subsequent growth and induction of either beta-galactosidase or tryptophanase much more adversely in E. coli strain BB than in E. coli strain K-12. Inducation of tryptophanase was reduced by the EDTA treatment significantly more than induction of beta-galactosidase in both strains. Addition of 2.5 x 10(-3)m cAMP appeared partially to reverse the inhibitory effect of the EDTA treatment on enzyme induction but did not restore normal growth.
 ...
PMID:Catabolite repression of tryptophanase in Escherichia coli. 432 48

Cyclic guanosine 3',5'-monophosphate inhibits the synthesis of beta-galactosidase and tryptophanase in cultures of Escherichia coli growing in minimal media with glucose or glycerol as the carbon source. Cyclic guanosine 3',5'-monophosphate acts at the transcriptional level in the lac operon, it exerts its action at the promoter site of the operon, and requires the presence of functional cyclic adenosine 3',5'-monophosphate receptor protein.
 ...
PMID:Effect of cyclic guanosine 3,5-monophosphate on the synthesis of enzymes sensitive to caatabolite repression in intact cells of Escherichia coli. 437 46

1. The intermediary metabolism of two strains of Escherichia coli has been examined. One strain (Q22) exhibits acute transient repression of beta-galactosidase synthesis when glucose is supplied to cells growing on glycerol; the other strain (W3110) does not. The two strains do not differ genetically in their lac operons. 2. Strain Q22 uses about twice as much glucose as strain W3110 per unit of cell mass produced. 3. Pentose phosphate-cycle activity in the presence of glucose is much stronger in strain Q22 than in strain W3110. 4. In strain Q22 the pool sizes of glucose 6-phosphate, 6-phosphogluconate, fructose 1,6-diphosphate and NADPH increase when glucose is added to cells growing on glycerol, and beta-galactosidase synthesis is severely inhibited. After about 1hr. the synthesis of beta-galactosidase is partly resumed, and the pool sizes of the four compounds fall. ATP, NADH and several other phosphorylated compounds show no concentration changes. 5. These concentration changes do not occur in strain W3110, in which beta-galactosidase synthesis is only rather weakly repressed by glucose. 6. It is suggested that repression of enzyme synthesis by glucose requires the rapid operation of the pentose phosphate cycle, and is mediated by one of the four substances whose concentration rises and later falls in strain Q22. A definite choice of effector from among these four possibilities cannot at present be made.
 ...
PMID:Pool sizes of metabolic intermediates and their relation to glucose repression of beta-galactosidase synthesis in Escherichia coli. 438 55

1. Saline extract of sheep pancreas acetone-dried powder was shown to catalyse acyl ester hydrolysis of spinach leaf galactosyl diglycerides and also galactosylglucosyl diglyceride of Lactobacillus casei. 2. Sodium deoxycholate stimulated the enzyme activity. Ca(2+) had no effect on the hydrolysis of monogalactosyl diglyceride, but it enhanced that of digalactosyl diglyceride. When added together, there was considerably less activity with both the substrates. 3. Optimal hydrolysis was observed at pH7.2. 4. The initial point of hydrolysis was at position-1, leading to the formation of monogalactosyl monoglyceride and digalactosyl monoglyceride. Further hydrolysis to the corresponding galactosylglycerols and later to galactose and glycerol was also observed, indicating the presence of alpha- and beta-galactosidases in the enzyme preparation. 5. Formation of monogalactosyl diglyceride from digalactosyl diglyceride by the action of alpha-galactosidase was noted. 6. Monogalactosyl diglyceride was also hydrolysed by beta-galactosidase to a limited extent, giving rise to diacylglycerol and galactose. 7. Attempts at purification of monogalactosyl diglyceride acyl hydrolase by using protamine sulphate treatment, Sephadex G-100 filtration and DEAE-cellulose chromatography gave a partially purified enzyme which showed 9- and 81-fold higher specific activity towards monogalactosyl diglyceride and digalactosyl diglyceride respectively. This still showed acyl ester hydrolysis activity towards methyl oleate, phosphatidylcholine and triacylglycerol. 8. When sheep, rat and guinea-pig tissues were compared, guinea-pig tissues showed the highest activity towards both monogalactosyl diglyceride and digalactosyl diglyceride. In all the species pancreas showed higher activity than intestine.
 ...
PMID:Degradation of monogalactosyl diglyceride and digalactosyl diglyceride by sheep pancreatic enzymes. 446 78

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 >>