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 general methodology used for the determination of lactose in milk is considered, namely, polarimetry, gravimetry, infrared, colorimetry, gas-liquid chromatography, and high pressure liquid chromatography. The criteria for selecting an ideal analytical method followed by the relevance of most of these criteria in enzymatic methodology are discussed. The principle of the Boehringer-Mannheim method is presented, i.e., lactose is hydrolyzed to glucose and beta-galactose in the presence of beta-galactosidase and water. beta-Galactose is then oxidized by nicotinamide-adenine dinucleotide to galactonic acid in the presence of beta-galactose dehydrogenase. The amount of reduced nicotinamide-adenine dinucleotide formed is stoichiometric with the amount of lactose and is measured at 340 nm in a spectrophotometer possessing a slit width of less than or equal to 10 nm. The results of a recent Association of Official Analytical Chemists collaborative study of the B-M method are presented. From the overall mean of results on all samples, determinations by the enzymatic method averaged .49% lower than by the Association of Official Analytical Chemists gravimetric method. Standard deviations were similar for three sets of blind duplicates, which ranged between 3.67 and 4.55% lactose. F-Values revealed that variations between means obtained by laboratories differed significantly as compared with variations within laboratory means. The method has received Official First Action recognition by Association of Official Analytical Chemists.
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PMID:Determination of lactose by an enzymatic method. 406 42

1. Lipopolysaccharides have been isolated from ;smooth' (S) strains of Salmonella friedenau and Salmonella poona by the phenol-water method and purified in the preparative ultracentrifuge. 2. These lipopolysaccharides are serologically indistinguishable and on partial acid hydrolysis the same series of oligosaccharides was obtained in each instance. 3. The results of quantitative micro-analysis, borohydride reduction, periodate oxidation, Morgan-Elson reactions and enzymic hydrolysis with beta-galactosidase on the isolated oligosaccharides indicate that the O-specific side chains of these lipopolysaccharides have a repeating pentasaccharide unit that is beta-d-galactosyl-(1-->3)-N-acetylgalactosaminyl-(1-->3)-N-acetylgalactosaminyl-(1-->4)-l-fucose with a d-glucose residue bound at an undetermined point on this structure. 4. Two oligosaccharides, a glucosyl-galactose and an N-acetylglucosaminylglucose, have also been isolated and these seem to be identical with oligosaccharides obtained from ;rough' (R) Salmonella lipopolysaccharides. These findings are in accordance with the view that Salmonella S-lipopolysaccharides have a core that consists of R-lipopolysaccharide.
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PMID:The immunochemistry of Salmonella chemotype VI O-antigens. The structure of oligosaccharides from Salmonella group G (o 13,22) lipopolysaccharides. 428 77

Dissociated sponge cell system has proved to be a useful model to study the process of cell aggregation both on cellular and subcellular level. The purpose of this review is to discuss recent results obtained from experiments with the marine sponge Geodia cydonium. Dissociated cells form functional aggregates during a process which can be sub-divided into three phases: first, formation of small primary aggregates in the presence of Ca2+; second, formation of secondary aggregates in the presence of an aggregation factor and third, reconstitution of a functional system of water-containing channels by rearrangement in the secondary aggregates. On subcellular level a series of macromolecules are known which are involved in the control of aggregation and separation of sponge cells: Aggregation factor, aggregation receptor, anti-aggregation receptor, beta-glucuronidase, beta-glucuronosyltransferase, beta-galactosyltransferase, beta-galactosidase and a lectin. These components might be linked in the following sequence: (a) Activation of the aggregation receptor by its enzymic glucuronylation; (b) Adhesive recognition of the cells, mediated by the aggregation factor and the glucuronylated aggregation receptor; (c) Inactivation of the aggregation receptor by its deglucuronylation with the membrane-associated beta-glucuronidase; (d) Cell separation due to either the loss of the recognition site (glucuronic acid) of the aggregation receptor for the aggregation factor or to an inactivation of the aggregation factor by the anti-aggregation receptor. The activity of the anti-aggregation receptor is most likely controlled by the Geodia lectin. The events leading to cell-cell recognition cause a change in the following metabolic events: Increase of oxygen uptake, decrease of cyclic AMP level, increase of cyclic GMP level and stimulation of programmed syntheses.
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PMID:Sponge cell aggregation. 624 12

A double antibody enzyme immunoassay of plasma cortisol was established using beta-galactosidase from E. coli as the tracer. Cortisol-21-hemisuccinate was conjugated with beta-galactosidase using a water-soluble carbodiimide. An antibody raised in the rabbit against cortisol-21-hemisuccinate-bovine serum albumin was used as the first antibody and anti-rabbit gamma-globulin goat serum was used as the second. The sensitivity of the present enzyme immunoassay was 25 pg/tube. The method satisfied general reliability criteria regarding specificity, accuracy and precision. Plasma cortisol levels estimated by the enzyme immunoassay was highly correlated (r = 0.99, P less than 0.005) with the levels measured by radioimmunoassay. This method of enzyme immunoassay was found to be of practical application to the routine assay of plasma cortisol.
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PMID:Double antibody enzyme immunoassay of cortisol in bovine plasma. 627 Aug 51

Verification of membrane filter total coliform colonies from drinking water was increased 87% by testing for the presence of beta-galactosidase and cytochrome oxidase, compared with verification by determination of gas production in lauryl tryptose broth. Over 90% of the coliforms verified by testing for beta-galactosidase and cytochrome oxidase were representative of the typical coliform genera.
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PMID:Comparison of verification procedures for the membrane filter total coliform technique. 634 33

beta-Galactosidase (beta-D-galactoside galactohydrolase, EC 3.2.1.23) purified from Aspergillus oryzae was modified with 2,4,6-trichloro-s-triazine derivatives of polyethylene glycol (activated BPEG) having molecular weights of 600, 1500, 2000, and 4000. Polyethylene glycol derivatives were attached to 6 of the 12 amino groups exposed on the surface of the enzyme. Upon modification, the enzymatic activity for a water-soluble substrate, o-nitrophenyl beta-D-galactopyranoside, was reduced with increasing molecular weight of the activated BPEG. On the contrary, the enzymatic activity for another substrate, 4-methylumbelliferyl beta-D-galactopyranoside, was increased upon modification. The Michaelis constants of native and modified enzymes for these two substrates were virtually the same. The effect of the modification was more marked in the enzymatic hydrolysis of the beta-galactosidic bond of amphipathic substrates. A fluorescent analog of naturally occurring galactocerebroside, 1-O-galactosyl-2-N-(1-dimethylaminonaphthalene-5-sulfonyl)-sphingosine, was hydrolyzed more rapidly by the modified enzyme than by the native one. The enzyme modified with activated BPEG of 1500 Da had the highest activity for this substrate. The beta-galactosidic bond of the terminal galactose of GM1-ganglioside (II3NeuAcGgOse4Cer, galactosyl-N-acetylgalactosaminyl-(N-acetylneuraminosyl)-galactosyl -glucosylceramide) was cleaved by the modified but not by the native enzyme.
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PMID:Alteration of the substrate specificity of Aspergillus oryzae beta-galactosidase by modification with polyethylene glycol. 643 28

An enzyme immunoassay of progesterone was established by using beta-galactosidase from E. coli as a label. The enzyme was conjugated with 11 alpha-hydroxyprogesterone-hemisuccinate using water-soluble carbodiimide. Rabbit antiserum to 11 alpha-hydroxyprogesterone-hemisuccinate-bovine serum albumin was previously obtained and anti-rabbit gamma globulin goat serum was used as second antibody. The enzyme activity was measured by utilizing hydrolysis of O-nitrophenyl-beta-D-galactopyranoside. The least detectable concentration of progesterone was 12 pg per tube. The measurable range of progesterone in 0.1 ml of bovine serum was between 0.25 ng/ml and 10 ng/ml. This method satisfied the general criteria regarding specifity, precision and recovery rate. Correlation between the progesterone levels determined by enzyme immunoassay and radioimmunoassay was quite high (r = 0.99, P less than or equal to 0.01). The present enzyme immunoassay can be applied for practical and routine analysis of serum progesterone.
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PMID:Practical procedure for enzyme immunoassay of progesterone in bovine serum. 676 71

Oxygen-18 leaving group kinetic isotope effects (KIEs) have been determined on both Vmax (V) and Vmax/Km (V/K) for the beta-galactosidase-catalyzed hydrolysis of p-nitrophenyl beta-D-galactoside (I) and 2,4-dinitrophenyl beta-D-galactoside (II). The former substrate exhibits KIEs of 1.022 +/- 0.002 and 1.014 +/- 0.003 on V and V/K, respectively, while corresponding KIEs for the latter are 1.002 +/- 0.0009 and 1.030 +/- 0.003. These results indicate that bond scission is largely rate determining for I but not for II at substrate saturation. The first irreversible step for both substrates must involve cleavage of the bond to the nitrophenyl leaving group. The mechanism proposed for this reaction is characterized by two parallel pathways for substrate hydrolysis. The predominant route for all but the most reactive substrates involves a SN2 nucleophilic displacement of aglycon by the enzyme to yield a covalent galactosyl-enzyme which in turn is hydrolyzed via a nucleophilic attach by water. The most reactive substrates (e.g., II) from transiently an enzyme-bound galactosyl oxo-carbonium ion which partitions between enzyme to give the covalent galactosyl-enzyme and H2O to yield galactose.
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PMID:Oxygen-18 leaving group kinetic isotope effects on the hydrolysis of nitrophenyl glycosides. 1. beta-galactosidease-catalyzed hydrolysis. 678 82

The authors studied combined effect of aniline (20 mg/kg for a period of 4 weeks in drinking water) and nitrosodimethylamine (NDMA) (30 mg/kg, a single intragastric dose) on the activity of enzymes of different subcellular structures: endoplasmic reticulum (cytochromes P450, B5, acetylesterase), mitochondria (malate dehydrogenase) and the content of N-acetylneuraminic acid in rat liver and of lysosomes (beta-glucuronidase, beta-galactosidase). The combined action of NDMA and aniline was accompanied by more pronounced changes in the indices under investigation than isolated administration of the given chemical substances. The most pronounced aggravation of the unfavourable changes was observed in the activity of enzymes connected with the processes of oxidation and energy supply to the cell (malate dehydrogenase) and the metabolism of glucuronides (beta-glucuronidase) as well as in the content of N-acetylneuraminic acid. This may be connected with the modifying effect of aniline on the toxic effect of NDMA.
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PMID:Combined effect of nitrosodimethylamine and aniline on the enzyme systems of subcelluar structures. 680 54

Trehalose diesters (natural 6,6'-trehalose dimycolate from Mycobacterium tuberculosis or synthetic (a 76 carbon atom analogue)), when suspended in water, give stable and well-defined emulsions. These emulsions, injected i.p. in mice significantly limit the growth of P815 syngeneic mastocytoma cells. They elicit macrophages with a cytostatic activity against P815 cells in vitro, strong enough to be expressed at low effector to target ratios (E/T = 1.4) or after a short coincubation period (2 hr). The antitumor potential of these macrophages seems to coincide with their ability to release H2O2 upon pharmacologic triggering. Depressed levels of alkaline phosphodiesterase and beta-galactosidase are proposed as other biochemical markers of cytostatic macrophages.
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PMID:Antitumor activity and hydrogen peroxide release by macrophages elicited by trehalose diesters. 680 86


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