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)

Phospho-beta-galactosidase (P-beta-gal), the enzyme which catalyzes the first step in the metabolism of intracellular lactose phosphate, occurred at high specific activity in the cytoplasm in 12 of 13 strains of streptococcus mutans grown on lactose but not other carbon sources. The P-beta-gal from S. mutans SL1 was purified 13-fold using diethylaminoethyl-cellulose ion exchange and agarose A--0.5 M molecular exclusion column chromatography. The molecualr weight of the enzyme was estimated to be 40,000, and its pH optimum was 6.5 in three different buffer systems. P-beta-gal activity was inhibited by Co2+, Zn2+, and Cu2+, but other cations, ethylenediaminetetraacetic acid, orthophosphate, and fluoride had no effect upon enzyme activity. The kinetic response of P-beta-gal to a model substrate, o-nitrophenyl-beta-D-galactopyranoside-6-phosphate, obeyed Michaelis-Menten kinetics, and the Km for this substrate was 0.19 mM. In addition to being under genetic control, P-beta-gal activity was regulated by a number of biologically active metabolites. Enzyme activity was inhibited in a sigmoidal fashion by phosphoenolpyruvate. The M 0.5 V value for phosphoenolpyruvate was 2.8 mM, and the Hill coefficient (n) was 3. In addition, P-beta-gal exhibited strong inhibition by ATP, galactose-6-phosphate, and glucose-6-phosphate. In contrast to inhibition of P-beta-gal activity by phosphoenolpyruvate, the inhibition exerted by ATP, galactose-6-phosphate, and glucose-6-phosphate obeyed classical Michaelis-Menten kinetics; the Ki values for these inhibitors were 0.55, 1.6, and 4.0 mM, respectively.
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PMID:Regulation of lactose catabolism in Streptococcus mutans: purification and regulatory properties of phospho-beta-galactosidase. 3 99

An expression system that utilized yeast copper metallothionein promoter and ubiquitin fusion technology to express the human estrogen receptor gene in yeast is described. We have studied the biochemical and transcriptional regulatory properties of the human estrogen receptor. The biochemical properties of the yeast expressed receptors are identical to the receptors isolated from human tissue. Estradiol mediated activation of transcription by the receptor was studied by a reporter beta-galactosidase gene where expression was under the control of estrogen response elements. Using this expression system and a hyperpermeable yeast strain we have studied the effects of various antiestrogens on the regulation of estrogen receptor function. We demonstrate that tamoxifen and ICI 164,384 are capable of binding to the receptor but neither antiestrogen was able to block the estradiol mediated increase in transcription. In fact, both antiestrogens exerted weak agonist activity in this system.
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PMID:Human estrogen receptor regulation in a yeast model system and studies on receptor agonists and antagonists. 132 95

The czcR gene, one of the two control genes responsible for induction of resistance to Co2+, Zn2+, and Cd2+ (czc system) in the Alcaligenes eutrophus plasmid pMOL30, was cloned and characterized. The 1,376-bp sequence upstream of the czcCBAD structural genes encodes a 41.4-kDa protein, the czcR gene product, transcribed in the opposite direction of that of the czcCBAD genes. The putative CzcR polypeptide (355 amino acid residues) contains 11 cysteine and 14 histidine residues which might form metal cation-binding sites. A czcC::lacZ reporter gene translational fusion was constructed, inserted into plasmid pMOL30 in A. eutrophus, and expressed under the control of CzcR. Zn2+, Co2+, and Cd2+, as well as Ni2+, Cu2+, Hg2+, and Mn2+ and even Al3+, served as inducers of beta-galactosidase activity. Besides the CzcR protein, the membrane-bound CzcD protein was essential for induction of czc. The CzcR and CzcD proteins display no sequence similarity to two-component regulatory systems of a sensor and a response activator type; however, CzcD has 34% identity with the ZRC-1 protein, which mediates zinc resistance in Saccharomyces cerevisiae (A. Kamizomo, M. Nishizawa, Y. Teranishi, K. Murata, and A. Kimura, Mol. Gen. Genet. 219:161-167, 1989).
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PMID:CzcR and CzcD, gene products affecting regulation of resistance to cobalt, zinc, and cadmium (czc system) in Alcaligenes eutrophus. 145 58

Conjugation of the protein-reactive drugs D-penicillamine (PA) and benzylpenicillin (BP) to immune cells to generate drug-derived antigenic determinants has been implicated in drug-induced allergies and autoimmunity. We have therefore developed an in vitro system to demonstrate and characterize the formation of cellular antigens by these drugs. Binding of PA and BP to rat peritoneal exudate cells was detected by a cell ELISA, employing rabbit antisera specific for each drug, and an indicator system employing a second antibody coupled to biotin-streptavidin-beta-galactosidase. For both drugs, binding was detected over the concentration range 125-1000 micrograms/ml. PA bound cells rapidly (maximum binding within 10 min), whereas BP bound relatively slowly (maximum binding occurring later than 4 hr). A possible role for intracellular processing and cellular metabolic activity in the generation of these drug-derived antigenic determinants was examined. Pretreatment of the cells with the fixative paraformaldehyde significantly enhanced binding of PA but not BP. Treatment of cells with the lysosomotropic agents ammonium chloride or chloroquine, or with the metabolic inactivator sodium azide, did not affect the binding of either drug compared with untreated control cells. However, treatment with the oxidising agent copper sulphate, or the cellular activator phorbol myristate acetate, did significantly enhance binding of both drugs to the cells. Therefore, binding of PA and BP to the cell surface appears not to require an intracellular processing event to generate a recognizable antigenic determinant, but is enhanced by treatments that stimulate oxidative processes.
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PMID:Penicillamine and penicillin can generate antigenic determinants on rat peritoneal cells in vitro. 170 17

The psbDI and psbDII genes in Synechococcus sp. strain PCC 7942 encode the D2 polypeptide, an essential component of the photosystem II reaction center. Previous studies have demonstrated that transcripts from psbDII, but not psbDI, increase in response to high light intensity. Soluble proteins from Synechococcus cells shifted to high light were found to have affinity for DNA sequences upstream from the psbDII coding region. DNA mobility-shift and copper-phenanthroline footprinting assays of a 258-bp fragment revealed three distinct DNA-protein complexes that mapped to the untranslated leader region between +11 and +84. Deletion of the upstream flanking region to -42 had no effect on the expression of a psbDII-lacZ reporter gene or its induction by light, whereas a promoterless construct supported only minimal background levels of beta-galactosidase. A 4-bp deletion within the first protected region of the footprint decreased the beta-galactosidase activity to approximately 2% of that of the undeleted control, but gene expression remained responsive to light. Deletion of the three protected regions completely abolished both gene expression and light induction. These results suggest that the psbDII gene requires elements within the untranslated leader region for efficient gene expression, one of which may be involved in regulation by light.
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PMID:Expression of the psbDII gene in Synechococcus sp. strain PCC 7942 requires sequences downstream of the transcription start site. 193 47

1. The sialidase purified from the hepatopancreas of Penaeus japonicus is able to bind the acidic beta-galactosidase in vitro. No protective protein, Mr 32,000, was detected in either purified enzyme preparation. 2. The specific activity of the isolated sialidase is 55.0 mU/mg of protein. After polyacrylamide gel electrophoresis under denaturing conditions, the purified shrimp enzyme was found to consist of monomers of Mr 32,000. 3. The sialidase from shrimp has an isoelectric point (pI) of 4.6 +/- 0.1. 4. The shrimp enzyme has the pH optimum at 5.0 and its Km was 5.5 microM with 2'-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminic acid as substrate. The enzyme activity was inhibited by either Hg2+ or Cu2+ ions.
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PMID:A sialidase from the hepatopancreas of the shrimp Penaeus japonicus (Crustacea: Decapoda): reversible binding with the acidic beta-galactosidase. 198 76

The phototoxicities of six metalloporphyrin dimethylesters (i.e. cobalt (Co), copper (Cu), manganese (Mn), nickel (Ni), tin (Sn) and zinc (Zn) were investigated. Hemolysis of human erythrocytes and inactivation of two enzymes (acetylcholinesterase and beta-galactosidase) were used to assess the phototoxic efficacy of these metal chelates. Tin protoporphyrin (SnPP), the only porphyrin found to hemolyze erythrocytes at a concentration of 40 microM (radiation dose, 230 kJ m-2), was much less efficient than either free protoporphyrin IX or hematoporphyrin. SnPP completely inactivated beta-galactosidase at concentrations above 15 microM (radiation dose, 75 kJ m-2) and drastically interfered with acetylcholinesterase activity at a concentration of 150 microM (radiation dose, 75 kJ m-2). CoPP, CuPP, MnPP, NiPP and ZnPP were ineffective photohemolytic agents at 40 microM (radiation dose, 230 kJ m-2), but inactivated acetylcholinesterase and beta-galactosidase activity to varying degrees. These results suggest that (i) metal ions reduce the phototoxicity of protoporphyrin IX, (ii) different metal ions reduce the phototoxic activity of protoporphyrin IX to different degrees and (iii) the biological activities of the various metal complexes vary in different assay systems.
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PMID:Metalloporphyrin phototoxicity. 212 21

Trapping by magnetic polyethyleneimine (PEI) microcapsules was utilized to investigate the influence in male rats of dose, human dietary composition and time-dependence on reactive metabolites of benzo[a]pyrene (B[a]P) in the gastrointestinal (GI) tract; also, PEI microcapsules modified with copper phthalocyanine tetrasulphonic acid (CPTS) were tested in vivo for trapping of endogenous mutagens having planar molecular structure. In a preliminary experiment the PEI microcapsules were administered by gavage at 0, 24 and 48 h, with [14C]B[a]P at 2 h to chow-fed BDVI rats; microcapsules were recovered from faeces collected at 24, 48 and 72 h, and then subjected to an extraction sequence showing that the trapped B[a]P metabolites were inconsistent with B[a]P diol epoxide trapping (as previously found) and unaltered by elapsed time or 5-fold dose alteration of B[a]P. Then five groups of F344 rats were fed isocalorically either one of four low-fat human diets or rat chow; in order to investigate influences of diet both on B[a]P and endogenous mutagens, half of each group was tested at 2 weeks with this PEI microcapsule/[14C]B[a]P protocol and then at 3 weeks, PEI-CPTS microcapsules (two gavages). So as to provide a cross-over comparison, the other half of each group was first tested with PEI-CPTS microcapsules followed by PEI microcapsules/[14C]B[a]P 1 week later. The human diets were prepared from cooked British foods so as to simulate the adequate intake of all nutrients required by humans; but with 3-fold differences in intake levels of beef and dietary fibre non-starch polysaccharide (NSP), while ensuring the same intake of available energy, protein, fat and calcium. They gave very similar body-weight gains in the four groups but greatly reduced faecal weight, protein and total faecal enzyme activity compared with chow; the extraction pattern of microcapsule-trapped B[a]P metabolite radioactivity was not significantly altered. However, human diet consumption caused a 2- to 6-fold increase in B[a]P metabolite binding to microcapsules and reductions in microcapsule recovery, net 70-h B[a]P excretion, faecal protein and total activities for beta-glucuronidase and beta-galactosidase; these effects were more pronounced after 3 weeks, presumably due to prolonged dietary adaptation. Increased NSP in human diets significantly increased the B[a]P metabolite excretion and marginally reduced the microcapsule binding. The increase in microcapsule binding of B[a]P metabolites, interpreted as reflecting an increased amount of reactive metabolites encountered, was related to the dietary intake weight ratio of beef/NSP.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Modulating effects in human diets of dietary fibre and beef, and of time and dose on the reactive microcapsule trapping of benzo[a]pyrene metabolites in the rat gastrointestinal tract. 215 56

The ACE1 gene of the yeast Saccharomyces cerevisiae is required for copper-inducible transcription of the metallothionein gene (CUP1). The sequence of the cloned ACE1 gene predicted an open reading frame for translation of a 225-amino-acid polypeptide. This polypeptide was characterized by an amino-terminal half rich in cysteine residues and positively charged amino acids. The arrangement of many of the 12 cysteines in the configuration Cys-X-Cys or Cys-X-X-Cys suggested that the ACE1 protein may bind metal ions. The carboxyl-terminal half of the ACE1 protein was devoid of cysteines but was highly acidic in nature. The ability of a bifunctional ACE1-beta-galactosidase fusion protein to accumulate in yeast cell nuclei was consistent with the possibility that ACE1 plays a direct role in the regulation of copper-inducible transcription of the yeast metallothionein gene.
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PMID:A cysteine-rich nuclear protein activates yeast metallothionein gene transcription. 265 99

The cDNAs encoding full-length chicken oviduct progesterone receptor B (PRB) and a truncated receptor (C1C2) lacking the amino-terminal domain were expressed in yeast (Saccharomyces cerevisiae) using a ubiquitin fusion system. The expression of the fusion protein is under the control of a copper-responsive yeast metallothionein promoter, and the fusion protein is subsequently cleaved by the yeast host enzyme to produce receptor protein. Western immunoblot analyses of yeast extracts containing full-length PRB revealed a polypeptide co-migrating with authentic chicken oviduct PRB. Using a polyclonal antibody (907) directed against the "hinge" region of the authentic chicken progesterone receptor, a 42-kDa polypeptide was detected by Western analysis in yeast extracts containing C1C2 receptors. Standard hormone binding assays indicated that these receptors produced in yeast cells exhibited steroid binding affinity and specificity characteristic of the authentic chicken progesterone receptor. To test for progesterone receptor-mediated activation of transcription in yeast, reporter plasmids were constructed to transform yeast cells expressing PRB or C1C2 receptors. The reporter gene contained two copies of a progesterone response element upstream of the yeast proximal CYC1 promoter fused to the beta-galactosidase gene of Escherichia coli. The induction of beta-galactosidase activity by PRB and C1C2 was strictly dependent on specific ligand and the presence of a progesterone response element. However, overproduced C1C2 receptors had an adverse effect on the transcription of the lacZ gene. It was found that when overproduced C1C2 was activated by progesterone, an inhibitory effect on normal yeast cell growth was evident. These observations suggest that C1C2 is a potent trans-acting factor in yeast and that the amino-terminal domain of the chicken progesterone receptor may play a role in selective modulation of target gene activation.
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PMID:Expression of functional chicken oviduct progesterone receptors in yeast (Saccharomyces cerevisiae). 268 42


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