Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.10.1 (ERK)
 95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Conformational changes in histone H2A (ALK, F2A2, IIbl) as a function of ionic strength and pH have been followed using high resolution nuclear magnetic resonance (NMR), circular dichroism (CD), and infrared (ir). While change in pH from 3 to 7 (no added salt) causes little structural change, added salt induces the formation of both alpha helix (28 percent maximum) and intermolecular associates in the region of the molecule between 25 and 113. No beta structure was observed at high salt. By the use of different salts it was shown that the structural changes were due largely to nonspecific counterion screening by the added anion. Comparison of observed with simulated NMR spectra has led to the proposal that an ionic strength dependent equilibrium exists between largely unstructured coil molecules and fully structured and aggregated molecules. NMR spectra of H2A obtained in the presence of DNA showed that both the N- and C-terminal regions bind to DNA, i.e., not the portion of the chain that is involved in interhistone interactions.
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PMID:Conformations and interactions of histone H2A (F2A2, ALK). 23 68

The soluble dextransucrase (EC 2.4.1.5) activity produced by Streptococcus mutans strain 6715 during growth on a chemically defined synthetic medium (FMS) was compared to enzyme from glucose broth cultures (TSB). Growth on the two media was similar. The specific activity of ammonium sulfate-precipitated FMC enzyme was 17 times greater than similar TSB enzyme preparations. The FMC enzyme was stimulated 11-fold, whereas the TSB enzyme was stimulated 1.2-fold by the addition of exogenous primer dextran. In contrast to the TSB enzyme, the FMC activity could be disaggregated to a low-molecular-weight form by 1 M salt. Thus, low-molecular-weight S. mutans dextransucrase activity free of contaminating primer glucan may be readily obtained after growth of the bacterium in a chemically defined sucrose-free medium.
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PMID:Streptococcus mutans dextransucrase: availability of disaggregated enzyme after growth in a chemically defined medium. 127 Jan 53

A study of the adhesive interface between 4-MET/MMA-TBB resin and hydroxyapatite or bovine enamel was reported. The present report is a continuation of that study. The possible chemical interaction between 4-methacryloxyethyl trimellitic acid (4-MET) and bovine or human dentin was examined by laser Raman spectroscopy. A 4-MET monomer solution was prepared by evaporating two thirds of the methyl methacrylate (MMA) in a commercial dentin adhesive. The solution was then applied to a dentin surface after treating the surface with an aqueous solution of 10% citric acid containing 3% ferric chloride. A salt formed on both bovine and human dentin surfaces. This salt was formed by the process we previously reported in which 4-MET formed a salt on the hydroxyapatite and bovine enamel. No evidence was observed of chemical reaction between 4-MET and any organic component in the dentin.
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PMID:Laser-Raman spectroscopic study of the adhesive interface; analysis between 4-META/MMA-TBB resin and bovine or human dentin. 139 87

The possible chemical interaction between synthetic hydroxyapatite or bovine enamel and a functional monomer of 4-methacryloxyethyl trimellitic acid (4-MET) diluted in methyl methacrylate (MMA) was examined by measuring the Raman spectra. It was concluded that the carboxyl group of 4-MET reacted with the calcium in the substrate to form a salt that was detected by the Raman band at around 1,380 cm-1. However, formation of the salt on the surface of the hydroxyapatite (HAP) with the carboxyl group, and polymerization of the 4-MET in the methacryl group near the surface were mutually exclusive reactions for the same 4-MET molecule.
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PMID:Laser-Raman Spectroscopic study of the adhesive interface between 4-MET/MMA-TBB resin and hydroxyapatite or bovine enamel. 166 97

The neu protooncogene (also called HER2 and c-erbB2) encodes a cell-surface tyrosine kinase structurally related to the receptor for the epidermal growth factor (EGF). We have previously reported that a candidate ligand for the neu receptor is secreted by ras-transformed fibroblasts. Biochemical analyses of the neu stimulatory activity indicate that the ligand is a 35-kDa glycoprotein that is heat stable but sensitive to reduction. The factor is precipitable by either high salt concentrations or acidic alcohol. Partial purification of the molecule by selective precipitation, heparin-agarose chromatography, and gel filtration in dilute acid resulted in an active ligand, which is capable of stimulating the protooncogenic receptor but is ineffective on the oncogenic neu protein, which is constitutively active. The purified fraction, however, retained the ability to stimulate also the related receptor for EGF, suggesting that these two receptors are functionally coupled through a bidirectional mechanism. Alternatively, the presumed ligand interacts simultaneously with both receptors. The presented biochemical characteristics of the factor are expected to enable a completely purified factor with which to explore these possibilities.
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PMID:Biochemical analysis of the ligand for the neu oncogenic receptor. 167 25

Extracts from Xenopus eggs capable of nuclear envelope assembly in vitro were fractionated by differential and density gradient centrifugation. Nuclear envelope assembly was found to require soluble components in the cytosol and two distinct particulate fractions, which we have called nuclear envelope precursor fractions A and B (NEP-A and NEP-B). Both NEP-A and NEP-B are sensitive to treatments with trypsin, sodium carbonate, and detergents, but can be distinguished from each other by their sensitivities to high salt and N-ethylmaleimide and by their levels of alpha-glucosidase activity. Vesicles in NEP-B bind to chromatin, whereas those in NEP-A do not. NEP-B may therefore be involved in the targeting of membranes to the surface of the chromatin, whereas NEP-A may provide a pool of vesicles that contributes many of the nuclear envelope membranes. NEP-B may also play a role in the assembly of nuclear pore complexes because the density of nuclear pores in the resulting envelope is dependent on the ratio of NEP-B to NEP-A in the reconstituted extract.
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PMID:A distinct vesicle population targets membranes and pore complexes to the nuclear envelope in Xenopus eggs. 199 30

Most urologists treating stone disease with any method (ESWL, PCL, URS) have encountered problems of poor stone visualization with fluoroscopy. This difficulty to localize urinary tract (UT) stones or fragments may result in incomplete stone extraction, prolonged surgery and increased risk of recurrence and post-operative complications. We have sought and found means to increase the radioopacity of mineral UT stones by a simple pre-operative perfusion technique. The capacity of radioopacification has first been demonstrated in in vitro incubations of fragments of human mineral stones with aqueous solutions of barium, of the lanthanides and of the two natural actinides. Most of the incubations led to considerable radio-contrast enhancement and heavy metal incorporation, measured by X-ray fluorescence analysis. Dogs with implanted human stone fragments were used as an in vivo model. The UT were perfused through a retrograde pyelic catheter with heavy metal salts solutions, the ensuing radioopacification of the implanted UT-stones was estimated by abdominal radiographies and the metal incorporation was measured on the retrieved stones. Considerable radioopacity enhancement together with heavy metal incorporation was observed for the following elements: Sr, Ba and the lanthanides Gd and Yb. The pathological evaluation of the urothelial linings from animals treated with lanthanide salt showed no toxic effects.
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PMID:Radio-contrast enhancement of urinary tract stones. 199 19

Lysozyme promotes fusion of negatively charged phospholipid vesicles prepared by ethanolic injection. Vesicle fusion was a leaky process as revealed by the release of encapsulated carboxyfluorescein or Tb-DPA complex. Extensive proteolysis of lysozyme inhibited the fusion process. The fusion process was critically dependent on the medium ionic strength; 100 mM of any salt was sufficient to inhibit totally the fusion activity of the protein. The high efficiency of lysozyme (80% RET) was almost constant in the pH range from 4.0 to 9.0, but it was sharply diminished when the pH of the medium was at the isoelectric point of the protein (pI 11.0). Fusion induced by chemically modified lysozyme, showed that the pH profile changed according to the isoelectric point of the protein derivative. These observations stress the importance of electrostatic interactions in the process of fusion induced by lysozyme.
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PMID:Lysozyme induced fusion of negatively charged phospholipid vesicles. 235 87

Control of mouse ribosomal RNA synthesis in response to extracellular signals is mediated by TIF-IA, a regulatory factor whose amount or activity correlates with cell proliferation. Factor TIF-IA interacts with RNA polymerase I (pol I), thus converting it into a transcriptionally active holoenzyme, which is able to initiate specifically at the rDNA promoter in the presence of the other auxiliary transcription initiation factors, designated TIF-IB, TIF-IC and UBF. With regard to several criteria, the growth-dependent factor TIF-IA behaves like a bacterial sigma factor: (i) it associates physically with pol I, (ii) it is required for initiation of transcription, (iii) it is present in limiting amounts and (iv) under certain salt conditions, it is chromatographically separable from the polymerase. In addition, evidence is presented that dephosphorylation of pol I abolishes in vitro transcription initiation from the ribosomal gene promoter without significantly affecting the polymerizing activity of the enzyme at nonspecific templates. The involvement of both a regulatory factor and post-translational modification of the transcribing enzyme provides an efficient and versatile mechanism of rDNA transcription regulation which enables the cell to adapt ribosome synthesis rapidly to a variety of extracellular signals.
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PMID:A growth-dependent transcription initiation factor (TIF-IA) interacting with RNA polymerase I regulates mouse ribosomal RNA synthesis. 239 Sep 74

The dioxathiadiaza-heteropentalenes, HEP-I (4,4-dimethyl-1,7-dioxa-2,6-diaza- 7 alpha lambda 4-thia-3H,5H-benzo[cd]pentalene), HEP-II (1,7-dioxa-2, 6-diaza-4, 7 alpha lambda 4-dithia-3H, 5H-benzo[cd]pentalene), HEP-III (1,7-dioxa-2,6-diaza-4, 7 alpha lambda 4-dithia-3H, 5H-benzo[cd]pentalene-4-oxide), and HEP-IV (1,7-dioxa-2,6-diaza-4,7 alpha lambda 4-dithia-3H, 5H-benzo[cd]pentalene-4,4-dioxide), inhibited growth of Escherichia coli in a simple glucose-salt medium, with their toxicities following the order of HEP-IV greater than HEP-III greater than HEP-II greater than HEP-I. These toxicities could be suppressed by yeast extract added to the glucose-salt medium. Yeast extract also facilitated maximal induction of superoxide dismutase (SOD) and catalase. The redox potentials of HEP-I-HEP-IV and the rates of oxygen uptake dependent on heteropentalenes in cyanide-resistant respiration of E. coli were correlated with the induction of SOD and catalase. Thus, the higher the redox potential of the compounds, the more potent they were for induction of enzyme production. Under anaerobic conditions, HEP-IV did not inhibit E. coli growth. These results indicate that HEP-I-HEP-IV can be reduced within the cell of E. coli and then reoxidized by molecular oxygen, generating O2- and H2O2. The toxicities of the heteropentalenes depend largely upon superoxide and/or hydrogen peroxide toxicity, and SOD and catalase provide a defense against the potential cytotoxicity of these species.
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PMID:Dioxathiadiaza-heteropentalenes mediate superoxide and hydrogen peroxide production in Escherichia coli. 253 60


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