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)

Changes in the activities of key enzymes responsible for utilization of methanol by recombinant strains of methylotrophic yeasts H. polymorpha R22-2B and H. polymorpha LAC-56 grown in a chemostat are described. The strain R22-2B displaying a high activity of dioxyacetone kinase had also a high activity of formaldehyde dehydrogenase, which increased the rate of dissimilation of formaldehyde. There was a decrease in ATP concentration in the strain LAC-56 oversynthesizing beta-galactosidase from Escherichia coli; this effect decreased the rate of assimilation of formaldehyde.
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PMID:[Biochemical response of recombinant Hansenula polymorpha strains to oversynthesis of homologous dioxyacetone kinase and bacterial beta-galactosidase]. 863 40

The beta-galactosidase from Thermoanaerobacterium thermosulfurigenes EM1 was found to be a dimer with a monomer molecular weight of about 85,000. It lacks the alpha-peptide and an important alpha-helix that are both needed for dimer-dimer interaction and there is no homology in other important dimer-dimer interaction areas. These differences in structure probably account for the dimeric (rather than tetrameric) structure. Only 0.19 Mg2+ bound per monomer and Mg2+ had only small effects on the activity and heat stability. The absence of residues equivalent to Glu-416 and His-418 (two of the three ligands to Mg2+ in the beta-galactosidase from Escherichia coli) probably accounts for the low level of Mg2+ binding and the consequent lack of response to Mg2+. Both Na+ and K+ also had no effect on the activity. The enzyme activity with o-nitrophenyl-beta-D-galactopyanoside (ONPG) was very similar to that with p-nitrophenyl-beta-D-beta-D-galactopyranoside (PNPG) and the ONPG pH profile was very similar to the PNPG pH profile. These differences are in contrast to the E.coli beta-galactosidase, which dramatically discriminates between these two substrates. The lack of discrimination by the T. thermosulfurigenes beta-galactosidase could be due to the absence of the sequence equivalent to residues 910-1023 of the E. coli beta-galactosidase. Trp-999 is probably of the most importance. Trp-999 of the E. coli beta-galactosidase is important for aglycone binding and ONPG and PNPG differ only in their aglycones. The suggestion that the aglycone site of the T. thermosulfurigenes beta-galactosidase is different was strengthened by competitive inhibition studies. Compared to E. coli beta-galactosidase, D-galactonolactone was a very good inhibitor of the T. thermosulfurigenes enzyme, while L-ribose inhibited poorly. These are transition-state analogs and the results indicate that T. thermosulfurigenes beta-galactosidase binds the transition state differently than does E. coli beta-galactosidase. Methanol and glucose were good acceptors of galactose, and allolactose was formed when glucose was the acceptor. Allolactose could not, however, be detected by TLC when lactose was the substrate. The differences noted may be due to the thermophilic nature of T. thermosulfurigenes.
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PMID:Quaternary structure, Mg2+ interactions, and some kinetic properties of the beta-galactosidase from Thermoanaerobacterium thermosulfurigenes EM1. 896 53

We have identified a novel nonsteroidal ecdysteroid agonist. This compound was isolated from a methanol extract of Ajuga reptans L. (Lamiaceae) and the structure was identified by spectroscopic methods as 8-O-acetylharpagide. We have characterised this compound as an ecdysteroid agonist in a transactivation assay using beta-galactosidase as the reporter gene regulated by ecdysteroid response elements. In this assay, 8-O-acetylharpagide has an EC50 of 22 microM. The compound also competes with tritiated-ponasterone A for binding to the Drosophila ecdysteroid receptor. Finally, it induces differentiation of Drosophila Kc cells as would be expected of an ecdysteroid agonist. This iridoid glycoside is common to several plant species and may play a role in the natural defense mechanisms of plants.
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PMID:8-O-acetylharpagide is a nonsteroidal ecdysteroid agonist. 896 63

The synthetic glycosides, p-nitrophenyl- and o-nitrophenyl-2-acetamido-2-deoxy-3-O-beta-D-galactopyranosyl-alpha- D-galactopyranosides, were found to be effective chromogenic substrates for an endo-alpha-N-acetyl-D-galactosaminidase. We did not experience any problems when these substrates were used for the screening of column fractions during the purification of the endoenzyme from Diplococcus pneumoniae culture filtrates. However, it should be pointed out that a combination of exo-beta-galactosidase, capable of cleaving beta 1-->3 linkages, and an exo-alpha-N-acetyl galactosaminidase would also liberate nitrophenol from the above substrates. The enzyme had no action on several other synthetic glycosides tested indicating the strict specificity of this enzyme for the disaccharide Gal beta-->GalNAc linked via an alpha-linkage to the aglycone. The enzyme was inactive when the aglycone was methanol but shows activity against the glycosides of phenol, nitrophenols, serine, and threonine. The use of p-nitrophenyl-2-acetamido-2-deoxy-3-O-beta -D-galactopyranosyl-beta-D-galactopyranoside, which is a competitive inhibitor of the endoenzyme, as an affinity ligand for the purification of the enzyme is described.
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PMID:Action of endo-alpha-N-acetyl-D-galactosaminidase on synthetic glycosides including chromogenic substrates. 976 98

(-)-(3aS,5S,6S.6aR)-3a,5,6,6a-Tetrahydro-5,6-isopropylide nedioxyfuro [2,3-d]isoxazole-3-methanol ((-)-5) has been tested toward 25 glycohydrolases and found to inhibit beta-galactosidase from Aspergillus niger (Ki = 18 microM) and that from Aspergillus orizae (Ki = 72 microM). Hydrolysis of the acetonide or exchange of CH2OH group for a CHO, CH2OMe or a CH2OMOM group suppresses the inhibitory activity.
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PMID:Specific, uncompetitive inhibition of beta-galactosidases by a 5,6-isopropylidenedioxyfuro[2,3-d]isoxazole-3-methanol derivative. 1002 44

2,6-Dideoxy-7-O-(beta-D-glucopyranosyl) 2,6-imino-D-glycero-L-gulo- heptitol (7-O-beta-D-glucopyranosyl-alpha-homonojirimycin, 1) was isolated from the 50% methanol extract of the whole plant of Lobelia sessilifolia (Campanulaceae), which was found to potently inhibit rice alpha-glucosidase. Adenophorae radix, roots of Adenophora spp. (Campanulaceae), yielded new homonojirimycin derivatives, adenophorine (2), 1-deoxyadenophorine (3), 5-deoxyadenophorine (4), 1-C-(5-amino-5-deoxy-beta-D-galactopyranosyl)butane (beta-1-C-butyl-deoxygalactonojirimycin, 5), and the 1-O-beta-D-glucosides of 2 (6) and 4 (7), in addition to the recently discovered alpha-1-C-ethylfagomine (8) and the known 1-deoxymannojirimycin (9) and 2R,5R-bis(hydroxymethyl)-3R,4R- dihydroxypyrrolidine (DMDP, 10). Compound 4 is a potent inhibitor of coffee bean alpha-galactosidase (IC50 = 6.4 microM) and a reasonably good inhibitor of bovine liver beta-galactosidase (IC50 = 34 microM). Compound 5 is a very specific and potent inhibitor of coffee bean alpha-galactosidase (IC50 = 0.71 microM). The glucosides 1 and 7 were potent inhibitors of various alpha-glucosidases, with IC50 values ranging from 1 to 0.1 microM. Furthermore, 1 potently inhibited porcine kidney trehalase (IC50 = 0.013 microM) but failed to inhibit alpha-galactosidase, whereas 7 was a potent inhibitor of alpha-galactosidase (IC50 = 1.7 microM) without trehalase inhibitory activity.
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PMID:Homonojirimycin analogues and their glucosides from Lobelia sessilifolia and Adenophora spp. (Campanulaceae). 1078 88

The biosynthesis of galactan was investigated using microsomal membranes isolated from suspension-cultured cells of potato (Solanum tuberosum L. var. AZY). Incubation of the microsomal membranes in the presence of UDP-[14C]galactose resulted in a radioactive product insoluble in 70% methanol. The product released only [14C]galactose upon acid hydrolysis. Treatment of the product with Aspergillus niger endo-1,4-beta-galactanase released 65-70% of the radioactivity to a 70%-methanol-soluble fraction. To a minor extent, [14C]galactose was also incorporated into proteins, however these galactoproteins were not a substrate for Aspergillus niger endo-1,4-beta-galactanase. Thus, the majority of the 14C-labelled product was 1,4-beta-galactan. Compounds released by the endo-1,4-beta-galactanase treatment were mainly [14C]galactose and [14C]galactobiose, indicating that the synthesized 1,4-beta-galactan was longer than a trimer. In vitro synthesis of 1,4-beta-galactan was most active with 6-d-old cells, which are in the middle of the linear growth phase. The optimal synthesis occurred at pH 6.0 in the presence of 7.5 mM Mn2+. Aspergillus aculeatus rhamnogalacturonase A digested at least 50% of the labelled product to smaller fragments of approx. 14 kDa, suggesting that the synthesized [14C]galactan was attached to the endogenous rhamnogalacturonan I. When rhamnogalacturonase A digests of the labelled product were subsequently treated with endo-1,4-beta-galactanase, radioactivity was not only found as [14C]galactose or [14C]galactobiose but also as larger fragments. The larger fragments were likely the [14C]galactose or [14C]galactobiose still attached to the rhamnogalacturonan backbone since treatment with beta-galactosidase together with endo-1,4-beta-galactanase digested all radioactivity to the fraction eluting as [14C]galactose. The data indicate that the majority of the [14C]galactan was attached directly to the rhamnose residues in rhamnogalacturonan I. Thus, isolated microsomal membranes contain enzyme activities to both initiate and elongate 1,4-beta-galactan sidechains in the endogenous pectic rhamnogalacturonan I.
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PMID:In vitro biosynthesis of 1,4-beta-galactan attached to rhamnogalacturonan I. 1078 56

Estrogenic and anti-estrogenic activities of diesel exhaust particles (DEP) were evaluated using yeast cells expressing the human estrogen receptor and the responsive element regulating the expression of the receptor gene for beta-galactosidase (Routledge and Sumpter, 1996). It was found that a suspension of whole DEP suspension is not estrogenic but that this preparation possesses the ability to reduce the estrogen-dependent reporter activity. DEP were serially extracted with hexane, benzene, dichloromethane, methanol, and 1 M ammonia, and the estrogenic and anti-estrogenic activities of these preparations were determined. None of the extracts of DEP were estrogenic, but the extracts of benzene, dichloromethane and methanol possessed anti-estrogenic activity, and the activity of estrogen in the presence of hexane extract was slightly decreased. These results indicated that DEP contain heterologous compounds having anti-estrogenic activity. It is thought that those compounds in DEP can modulate the activity of estrogen, leading to the distruption of balance between estrogen and androgen. In this paper, the environmental effects of DEP in relation to the endocrine disrupting effect of organic compounds in DEP are discussed.
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PMID:Anti-estrogenic activity of diesel exhaust particles. 1114 81

The effect of heavy metals and organic compounds on the activity of the enzyme beta-galactosidase in a standardized bioassay has been evaluated, considering future applications in environmental monitoring. The tests were done using a commercial extract of a hydrolase from the eukaryote yeast Kluyveromyces lactis and o-nitrophenyl-beta-D-galactopyranoside (ONPG) as substrate. The enzyme was exposed to Cr(VI), Cd(II), Cu(II), Ni(II), Pb(II), Hg(II), phenol, sodium dodecyl sulfate, methanol and pentachlorophenol for 5, 15, 30, and 60 min. According to the results, a 15 min exposure time was considered optimum for the performance of the assay. Results of tests with metals showed IC50 values ranging between 9.25mg/L for Cd(II) and 0.015mg/L for Hg(II), with an order of sensitivity of: Cd(II) < Ni(II) < Cr(VI) = Pb(II) < Cu(II) < Hg(II). Sensitivity to organic compounds ranged from 200 to 4,000 mg/L, showing a higher specificity to heavy metals. The present in vitro free enzyme test showed a similar behavior to other tests based on beta-galactosidase such as the MetPlate. Furthermore, when compared to data from the literature on acute toxicity assays currently used in environmental assessment, test results show good agreement regarding the sensitivity to metals. After standardization, the proposed test could be used as a rapid and low-cost assay when evaluating biological effects of heavy metals in monitoring programs.
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PMID:Development of a free beta-galactosidase in vitro test for the assessment of heavy metal toxicity. 1133 10

Genes coding for Vitreoscilla hemoglobin (VHb) with peroxisome targeting signal (PTS1) tag and beta-galactosidase were co-expressed in Pichia pastoris under the alcohol oxidase1 (AOX1) promoter. The expression of VHb-PTS1 had no positive effect on cell growth but significantly enhanced the whole cell beta-galactosidase activity to 4-fold higher than that of VHb-free cell in yeast extract/peptone/methanol medium under aerobic cultivation.
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PMID:Expression of the gene coding for bacterial hemoglobin improves beta-galactosidase production in a recombinant Pichia pastoris. 1451 50


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