Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have determined and refined the crystal structure of a recombinant calmodulin at 1.7 A resolution. The structure was determined by molecular replacement, using the 2.2 A published native bovine brain structure as the starting model. The final crystallographic R-factor, using 14,469 reflections in the 10.0 to 1.7 A range with structure factors exceeding 0.5 sigma, is 0.216. Bond lengths and bond angle distances have root-mean-square deviations from ideal values of 0.009 A and 0.032 A, respectively. The final model consists of 1279 non-hydrogen atoms, including four calcium ions, 1130 protein atoms, including three Asp118 side-chain atoms in double conformation, 139 water molecules and one ethanol molecule. The electron densities for residues 1 to 4 and 148 of calmodulin are poorly defined, and not included in our model, except for main-chain atoms of residue 4. The calmodulin structure from our crystals is very similar to the earlier 2.2 A structure described by Babu and coworkers with a root-mean-square deviation of 0.36 A. Calmodulin remains a dumb-bell-shaped molecule, with similar lobes and connected by a central alpha-helix. Each lobe contains three alpha-helices and two Ca2+ binding EF hand loops, with a short antiparallel beta-sheet between adjacent EF hand loops and one non-EF hand loop. There are some differences in the structure of the central helix. The crystal packing is extensively studied, and facile crystal growth along the z-axis of the triclinic crystals is explained. Herein, we describe hydrogen bonding in the various secondary structure elements and hydration of calmodulin.
J Mol Biol 1992 Dec 20
PMID:Calmodulin structure refined at 1.7 A resolution. 147 85

An acidic glycoconjugate could be extracted from a delipidated residue fraction of [3H]galactose, [3H]mannose or [32P]orthophosphate metabolically labeled Entamoeba histolytica with water/ethanol/diethylether/pyridine/NH4OH (15:15:5:1:0.017). The radioactively labeled glycoconjugate comprised 50-55% of the total [3H]galactose label incorporated into macromolecules. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of the radiolabeled glycoconjugate showed two diffuse smears centering around 110 kDa and 45 kDa. Similar profiles were observed for both [3H]galactose- and [32P]orthophosphate-labeled glycoconjugate. No such bands were visible in [35S]methionine-labeled material. The hydrophobic nature of this glycoconjugate was inferred from its chromatographic behavior on phenyl-Sepharose. The molecule was rendered hydrophilic after digestion with phosphatidylinositol-specific phospholipase C. It was also sensitive to deamination by nitrous acid. Mild acid hydrolysis led to its fragmentation into smaller molecules as revealed by Sepharose 4B chromatography. Paper chromatographic analysis of the depolymerized [3H]galactose- and [3H]mannose-labeled fragments revealed that each was sensitive to alkaline phosphatase. The major dephosphorylated fragment migrated as an apparent galactose and mannose containing disaccharide which migrated identically to the Gal beta 1-4Man disaccharide derived from the lipophosphoglycan of Leishmania donovani. The above data support the existence of a major acidic glycoconjugate in E. histolytica bearing striking structural similarities to the lipophosphoglycan of Leishmania.
Mol Biochem Parasitol 1992 Nov
PMID:Identification and partial characterization of a lipophosphoglycan from a pathogenic strain of Entamoeba histolytica. 147 94

The microaerophilic protozoon Trichomonas vaginals responds to extracellular changes in oxygen concentration: acetate, lactate, ethanol, H2 and CO2 formation, as well as glucose-depletion rates, are affected. All these variables except ethanol production rates, also differed between clinically metronidazole-sensitive (1910) and resistant (IR78 and CDC85) strains. Most interesting were the greatly increased glucose-scavenging rates of resistant isolates and their low specific activities of hydrogenase and H2 formation rates by comparison with the metronidazole-sensitive strain. Results suggest that all three strains of this parasite are well adapted to the O2 levels prevailing in situ (13-56 microM). Thus, vaginal oxygen tensions have more pronounced effects on the balances of fermentation products in the resistant strains, and results indicate that these strains may then use hydrogenosomal pathways to their advantage.
Mol Biochem Parasitol 1992 Nov
PMID:Influence of oxygen on the fermentative metabolism of metronidazole-sensitive and resistant strains of Trichomonas vaginalis. 147 4

Promastigotes from late log phase and 3-day stationary phase cultures of Leishmania donovani were collected, washed in buffer, and the cell pellet was treated with boiling KOH. A putative carbohydrate storage material was then precipitated and washed in ethanol/LiBr. This material did not liberate glucose when treated with amyloglucosidase, indicating that it was not glycogen. Acid hydrolysis released a hexose which was identified as mannose by several criteria. Considerably more of this mannan-like carbohydrate is present in cells from 3-day stationary phase than from late log phase cultures, consistent with the ability of 3-day stationary phase cells to survive in non-nutrient buffer and maintain oxygen consumption for longer than log phase cells. The amount of this mannan-like compound decreased by over 50% during a 3-h incubation in buffer of cells from 3-day stationary phase cultures. The presence of glucose during the incubation prevented the utilization of this carbohydrate, consistent with the possibility that it serves as an energy reserve.
Mol Biochem Parasitol 1992 Jul
PMID:Utilization of a carbohydrate reserve comprised primarily of mannose by Leishmania donovani. 150 39

We examined the effects of cholesterol on the membrane-disordering action of ethanol by using deuterium nuclear magnetic resonance (2H-NMR) and fluorescence spectroscopy. Specifically, the effects of ethanol were measured on the 2H-NMR spectra of di(perdeuteropalmitoyl)phosphatidylcholine (DPPC-d62) and on the steady-state emission anisotropy of diphenylhexatriene (DPH) incorporated into hydrated egg phosphatidylcholine (eggPC)/cholesterol dispersions. Analysis of the 2H-NMR spectra of DPPC-d62 incorporated into eggPC liposomes showed that the addition of cholesterol up to 30 mol% enhanced the ability of ethanol to disorder methylene groups all along the phospholipid acyl chains. This effect was somewhat greater toward the terminal methyl groups. However, above 30 mol% cholesterol, the bilayer-disordering action of ethanol on both the upper and lower portions of the acyl chains decreased to an apparent constant change up to the highest cholesterol content examined (50 mol%). Analysis of the fluorescence anisotropy of DPH, on the other hand, suggested that cholesterol attenuated the ability of ethanol to disorder the bilayers, which is in agreement with a previous EPR study [Chin and Goldstein, Mol Pharmacol 19: 425-431, 1981]. Re-analysis of our previous fluorescence anisotropy results with DPH incorporated into dispersions of brain-lipid extracts as a percent change [Johnson et al., Mol Pharmacol 15: 739-746, 1979] indicated that the chemical composition of the lipid bilayers also affects the apparent ability of cholesterol to modulate the membrane-disordering action of ethanol, because the addition of cholesterol to brain-lipid extracts had no significant effect on the membrane-disordering action of ethanol. Given the greater likelihood that the 2H-NMR probes accurately monitor bulk phospholipid properties, some caution is required in the analysis of the membrane-disordering actions of drugs using EPR and fluorescence spectroscopy.
 ...
PMID:A deuterium NMR and steady-state fluorescence anisotropy study of the effects of cholesterol on the lipid membrane-disordering actions of ethanol. 151 Jul 24

The technique of polymerase chain reaction (PCR) is potentially superior to existing methods for detecting rickettsial infections in ticks. For this reason, we developed assays for identifying rickettsial infections in ticks by PCR. Our assays amplified a 500 bp fragment from the gene encoding the rOmp B protein of Rickettsia rickettsii. The selected primers amplified fragments of the predicted size from all spotted fever group rickettsiae (R. rickettsii, R. parkeri, R. conorii, R. sibirica) tested. No amplified products were detected when typhus group rickettsiae (R. canada, R. prowazekii, R. typhi) were assayed. Using techniques described in this study, we reliably amplified the predicted product from hemolymph, saliva and ground leg tissue samples from live, partially fed, infected ticks. Samples derived from infected ticks preserved in 70% ethanol also were suitable for amplification by PCR. Similar assays performed with infected ticks preserved in 5% buffered formalin seldom gave positive results.
Mol Cell Probes 1992 Aug
PMID:Detection of Rickettsia rickettsii in saliva, hemolymph and triturated tissues of infected Dermacentor andersoni ticks by polymerase chain reaction. 152 3

In primary cultures of cerebellar granule cells, activation of the N-methyl-D-aspartate (NMDA) receptor leads to Ca2+ influx. Previous work showed that this response is selectively inhibited by acute exposure to low concentrations of ethanol. The present results demonstrate that the response to NMDA (measured as an increase in intracellular Ca2+ concentration, using fura-2 fluorescence) is significantly enhanced after chronic in vitro exposure of the cells to ethanol (100 mM for 2-4 days; 20 mM for 3 or more days). This enhancement is consistent with an increased number of NMDA receptors, with no change in receptor properties. Specifically, there was no change in the EC50 values for NMDA and glycine or in the magnitude of inhibition of the NMDA response by competitive or uncompetitive antagonists. There was also no change in the ability of acute ethanol to inhibit the NMDA response after chronic exposure of the cells to ethanol. Furthermore, chronic ethanol exposure did not alter depolarization-dependent increases in intracellular Ca2+ observed after exposure of the cells to 30 mM KCl. The data suggest that chronic ethanol exposure produces a selective up-regulation of NMDA receptor function. In the intact animal, such a change may be associated with particular symptoms of ethanol withdrawal, i.e., withdrawal seizures.
Mol Pharmacol 1992 Jun
PMID:Chronic exposure of cerebellar granule cells to ethanol results in increased N-methyl-D-aspartate receptor function. 153 16

Alkylformamides, for example N-methylformamide, are hepatotoxic in rodents and humans. The mechanism by which N-methylformamide exerts its hepatotoxicity involves metabolic oxidation at the formyl moiety to yield a short-lived intermediate, perhaps methyl isocyanate, which reacts with glutathione to afford S-(N-methylcarbamoyl)glutathione. The hypothesis that the cytochrome P450 isozyme CYP2E1 catalyzes the metabolic toxification of N-methylformamide was tested. Hepatocytes obtained from mice that had received acetone, an inducer of CYP2E1, were incubated for up to 4 hr with N-methylformamide (5 and 10 mM). Whereas N-methylformamide caused cytotoxicity in these cells, as measured by release from the cells of lactate dehydrogenase, it was barely toxic, under these conditions, to cells from untreated mice. Coincubation of N-methylformamide with dimethylsulfoxide (10 mM), a CYP2E1 inhibitor, for 4 or 6 hr abolished the hepatocytotoxicity of N-methylformamide. Metabolism of N-methylformamide to S-(N-methylcarbamoyl) glutathione was measured in incubates with liver microsomes from rats, mice, or humans in the presence of glutathione. Pretreatment of rodents with acetone or ethanol induced the rate of metabolism of N-methylformamide and of p-nitrophenol, a known CYP2E1 substrate, but it did not increase aminopyrine N-demethylation. Metabolism of N-methylformamide and p-nitrophenol was elevated in microsomes from animals that had received acetone (1%) in their drinking water for 1 week to 230% and 200%, respectively, of control values in mouse microsomes and to 310% and 240%, respectively, of control values in rat microsomes. Pretreatment of animals with 4-methylpyrazole (200 mg/kg intraperitoneally, once daily for 3 days) increased metabolism of N-methylformamide to 410% of control values in rat liver microsomes but was without effect on murine microsomal metabolism of N-methylformamide. The metabolism of this compound was strongly inhibited by the CYP2E1 substrates or inhibitors dimethylsulfoxide (1-100 mM), p-nitrophenol (100 microM), and diethyldithiocarbamate (100 microM), which did not affect aminopyrine N-demethylation. A polyclonal antibody against rat CYP2E1 (10 mg of IgG/nmol of cytochrome P450) inhibited N-methylformamide metabolism in liver microsomes from rats and from a human by 75% and 80%, respectively. The rate of metabolism of N-methylformamide to S-(N-methylcarbamoyl) glutathione was determined in liver microsomes from six humans and correlated with extent of metabolic hydroxylation of chlorzoxazone, a CYP2E1 probe, and with amount of immunodetectable enzyme using an anti-rat CYP2E1 antibody (r = 0.81 and 0.80, respectively). The results suggest that CYP2E1 is the predominant, if not sole, cytochrome P450 isozyme responsible for the metabolic toxification of hepatotoxic N-alkylformamides.
Mol Pharmacol 1992 Feb
PMID:Metabolic oxidation and toxification of N-methylformamide catalyzed by the cytochrome P450 isoenzyme CYP2E1. 153 6

A well-defined set of isogenic yeast strains has been constructed whereby each strain contains a different LPD::lacZ gene fusion integrated at the ura3 locus. These LPD::lacZ fusions differ in the amount of the LPD1 gene (encoding lipoamide dehydrogenase) that is fused to the lacZ reporter. Comparison of the beta-galactosidase activities of each strain during growth on glucose or ethanol revealed that some part of the LPD1 coding region between +13 and +700 is involved in activating gene expression in a carbon source-dependent manner. This activation occurs at the mRNA level, and is not mediated by changes in mRNA stability. Therefore, the LPD1 gene appears to contain a transcriptional enhancer that lies 3' to the transcriptional start site, and which responds to carbon source.
Mol Microbiol 1992 Jan
PMID:A 3' transcriptional enhancer within the coding sequence of a yeast gene encoding the common subunit of two multi-enzyme complexes. 154 8

Ethanol-inducible cytochrome P450 (P450IIE) is reported to be induced by ketosis. In the present study, the effects of a high fat diet on P450IIE induction and the relationship between ketone body concentration and P450IIE induction were studied by the following: 1) measurement of the activity of aniline hydroxylase, 2) immunoblot analysis for P450IIE protein, and 3) Northern blot analysis for P450IIE mRNA. The enzyme activities (aniline hydroxylase) in hepatic and renal microsomes were elevated about 2-3-fold by feeding with a high fat diet for 3 days. The increases in enzyme activities were also accompanied by 3-fold increases in immunoreactive P450IIE protein and its mRNA. In contrast, no differences were observed for the catalytic activities of N-alkoxyresorufin dealkylases or the amounts of immunoreactive P450IA and P450IIC, indicating a specific induction of P450IIE by high fat feeding. Furthermore, the increases in the levels of P450IIE mRNA correlated positively (r = 0.73) with plasma concentrations of acetoacetate and beta-hydroxybutyrate but not with that of acetone, which induces P450IIE without changing its mRNA level. Our data thus indicated that P450IIE induction during the ketosis of a high fat feeding appears to be due to pretranslational activation and that is similar to the induction mechanism of fasted and diabetic animals.
Mol Pharmacol 1992 Mar
PMID:Pretranslational activation of cytochrome P450IIE during ketosis induced by a high fat diet. 154 75


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>