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

To get a general rule for the relationship between hydrophobic effect and conformational stability, five Ile to Val and nine Val to Ala mutants (3SS mutants) from 3SS (C77A/C95A) human lysozyme were constructed. As known from previous studies, the 3SS protein lacking a disulfide bond between Cys77 and Cys95 is destabilized by enthalpic factors, as revealed by a decrease of about 20 kJ/mol in the denaturation Gibbs energy change (DeltaG) value, as compared to the wild-type protein, which has four disulfide bonds. In this study, the stabilities and structures of the 3SS mutants were determined by differential scanning calorimetry and X-ray crystal analysis, respectively, and compared with those of the mutants (4SS mutants) from the wild-type (4SS) protein published previously. The stabilities of all the 3SS mutants, except for V110A-3SS were decreased as compared with that of the 3SS protein, coinciding with the results for the 4SS mutants. The change in the denaturation Gibbs energy change (DeltaDeltaG) values of the 3SS mutants relative to the 3SS protein at the denaturation temperature (49.2 degreesC) of the 3SS protein at pH 2.7 were similar to those of the equivalent 4SS mutants relative to the wild-type at 64.9 degreesC. The Delta DeltaG values of the 3SS mutants correlated with the changes in hydrophobic surface area exposed upon denaturation (Delta DeltaASAHP) for all of the hydrophobic residues when the effects of the secondary structure propensity were considered. This correlation is identical with that previously found for the 4SS mutants. The linear relation between Delta DeltaG and Delta DeltaASAHP for all of the hydrophobic residues with the same slope was found also for the mutants of T4 lysozyme already reported, indicating that this is a general relationship between changes in conformational stability and changes in ASA values of hydrophobic residues due to mutations.
J Mol Biol 1998 Jul 24
PMID:A general rule for the relationship between hydrophobic effect and conformational stability of a protein: stability and structure of a series of hydrophobic mutants of human lysozyme. 967 1

Pathogenesis-related proteins of group 1 (PR-1) are strongly induced in plants by pathogen attack, exposure of the plants to (acetyl)salicylic acid (ASA, SA), and by developmental cues. Functional analysis of the PR-1a promoter identified a region of 139 bp (from -691 to -553) mediating expression of the GUS reporter gene in response to ASA. Inspection of this region revealed two TGACG elements reminiscent of activation sequence-1 (as-1). Recently, as-1 has been reported to be responsive to SA in the context of the CaMV 35S RNA promoter. To address the question of whether the as-1-like sequence may be of functional significance for the expression of the PR-1a gene, gel shift assays were performed with TGA1a, a protein been shown to interact with as-1 in vitro. TGA1a was found to bind to the PR-1a as-1-like sequence with similar specificity and affinity as to as-1. Furthermore, mutations were introduced in the as-1-like sequence in the context of the inducible 906 bp PR-1a promoter which are impaired in binding TGA1a in vitro. Significantly reduced levels of GUS reporter gene activity were obtained with the mutant promoter regions as compared to the wild-type PR-1a promoter in response to all stimuli in transgenic tobacco plants. Yet, mutation of the as-1-like sequence did not abolish induction of reporter gene expression. Taken together, these results suggest that the level of expression of the tobacco PR-1a gene is controlled by an as-1-like sequence motif in the PR-1a upstream region, possibly interacting with a factor related to TGA1a.
Plant Mol Biol 1998 Jul
PMID:An as-1-like motif controls the level of expression of the gene for the pathogenesis-related protein 1a from tobacco. 967 82

Radiation generates a variety of free radicals during the exposure of biological tissues through radiolysis of water. These free radicals are highly reactive and cause oxidative damage to biological molecules. This study examined the protective ability of aspirin against radiation induced oxidative stress. The study assessed the protective effect of aspirin (0.05 mM, 0.10 mM, 0.50 mM) on the generation of free radicals during exposure of J774A.1 macrophage cells to radiation (13.25 cGy). Approximately a 2.2-fold increase in superoxide anion formation as determined by cytochrome c reduction was observed following exposure of the cells to radiation for 20 one second exposures. Preincubation with aspirin exhibited a dose dependent decrease in free radical production as assessed by chemiluminescence and cytochrome c reduction. Aspirin also produced a concentration dependent reduction in radiation induced DNA damage in the cells. The data indicate that radiation of these cells results in production of reactive oxygen species and DNA damage, and aspirin can decrease these effects in a concentration dependent manner.
Res Commun Mol Pathol Pharmacol 1998 Sep
PMID:Protective ability of acetylsalicylic acid (aspirin) to scavenge radiation induced free radicals in J774A.1 macrophage cells. 987 84

Wounding corneal epithelium establishes a laterally oriented, DC electric field (EF). Corneal epithelial cells (CECs) cultured in similar physiological EFs migrate cathodally, but this requires serum growth factors. Migration depends also on the substrate. On fibronectin (FN) or laminin (LAM) substrates in EF, cells migrated faster and more directly cathodally. This also was serum dependent. Epidermal growth factor (EGF) restored cathodal-directed migration in serum-free medium. Therefore, the hypothesis that EGF is a serum constituent underlying both field-directed migration and enhanced migration on ECM molecules was tested. We used immunofluorescence, flow cytometry, and confocal microscopy and report that 1) EF exposure up-regulated the EGF receptor (EGFR); so also did growing cells on substrates of FN or LAM; and 2) EGFRs and actin accumulated in the cathodal-directed half of CECs, within 10 min in EF. The cathodal asymmetry of EGFR and actin staining was correlated, being most marked at the cell-substrate interface and showing similar patterns of asymmetry at various levels through a cell. At the cell-substrate interface, EGFRs and actin frequently colocalized as interdigitated, punctate spots resembling tank tracks. Cathodal accumulation of EGFR and actin did not occur in the absence of serum but were restored by adding ligand to serum-free medium. Inhibition of MAPK, one second messenger engaged by EGF, significantly reduced EF-directed cell migration. Transforming growth factor beta and fibroblast growth factor also restored cathodal-directed cell migration in serum-free medium. However, longer EF exposure was needed to show clear asymmetric distribution of the receptors for transforming growth factor beta and fibroblast growth factor. We propose that up-regulated expression and redistribution of EGFRs underlie cathodal-directed migration of CECs and directed migration induced by EF on FN and LAM.
Mol Biol Cell 1999 Apr
PMID:Electric field-directed cell motility involves up-regulated expression and asymmetric redistribution of the epidermal growth factor receptors and is enhanced by fibronectin and laminin. 1019 71

This study was conducted to investigate the effects of aging on collagen and collagenase expression by human dermal fibroblasts. To evaluate this effect, the expression of these ECM was determined and compared between either fetal and adult fibroblasts or dermal fibroblasts at various passages. A total of 13 cell strains, 8 fetal foreskin and 5 adult dermal fibroblasts, were grown to 80-90% confluency and their rates of cell proliferation and expression of mRNA for collagenase (MMP-1) and pro alpha1(I) chain of type I collagen was determined and compared. Fetal cells had a significantly higher rate of proliferation relative to adult fibroblasts evaluated within 10 days of culture. Northern analysis was used to evaluate the steady state levels of mRNA in these cells. The result of these experiments revealed a significantly greater expression of mRNA for collagenase (58.6 +/- 7.7 vs. 9.9 +/- 1.5, p < 0.05) in strains of adult fibroblasts. This was consistent with collagenase activity of conditioned medium derived from adult cells relative to fetal fibroblasts. However the expression of pro alpha1 (I) chain of type I collagen mRNA was not significantly (56.2 +/- 5.2 vs. 58.5 +/- 3.5) different between adult and fetal fibroblasts. This finding was confirmed by measuring total collagen production present in conditioned medium of these cells using hydroxyproline as an index for collagen production. The cellular response to IGF-1 and IFN-alpha2b as representatives of fibrogenic and anti-fibrogenic factors were also evaluated. When expression of collagenase was used as an indication for cellular response, the degree of this response to IGF-1 but not IFN-alpha2b was significantly greater in fetal relative to adult cells. Serial passage was also used as an in vitro model for aging fibroblasts and found a gradual reduction in pro alpha1(I) chain of type I collagen mRNA and hydroxyproline formation due to passaging. In conclusion, a slower rate of proliferation, a greater collagenase activity and expression of collagenase mRNA by aging fibroblasts could be some of the main reasons for attenuation of wound healing in elderly patients.
Mol Cell Biochem 1999 Apr
PMID:Aging differentially modulates the expression of collagen and collagenase in dermal fibroblasts. 1039 Nov 29

The highly conserved N-and C-terminal domains of IGFBPs are believed to participate in IGF binding, but only recently have some of the critical residues in the IGFBP sequence involved in ligand binding been identified. Here we describe two highly conserved amino acids in the C-terminal domain of rat IGFBP-5 that are involved in binding IGF-I. Site-directed mutagenesis was used to produce two mutants, G203K and Q209A, of rIGFBP-5. Relative to wild-type rIGFBP-5, an 8-fold reduction in affinity for human IGF-I was found for recombinant G203K protein in both IGF-I ligand blots and solution phase ligand binding assays, and a 7-and 6-fold reduction for Q209A respectively. This shows that Gly203 and Gln209 in IGFBP-5 are important determinants in binding IGF-I, and due to their complete conservation in all IGFBP sequences, we suggest that they are likely to be involved in binding IGF-I in all six binding proteins. In addition, these two non-basic residues lie within the ECM binding region (201-218) of IGFBP-5, demonstrating that the C-terminus contains partially overlapping IGF-I and ECM binding sites. We therefore propose that heparin binding to basic amino acids in IGFBP-5 between 201-218 may physically occlude subsequent interaction between IGF-I and Gly203/Gln209, and that this may explain previous work of others showing reduced affinity of ECM bound IGFBP-5 for IGF-I.
J Mol Endocrinol 1999 Aug
PMID:Amino acids within the extracellular matrix (ECM) binding region (201-218) of rat insulin-like growth factor binding protein (IGFBP)-5 are important determinants in binding IGF-I. 1042 23

The mechanism by which 5-aminosalicylic acid (5-ASA) reduces mucosal injury in colitis is undefined. In murine cells, 5-ASA modulates the expression of the inducible nitric oxide (NO) synthase, a potential mediator of colitic injury, but its effect on the human isoform is unknown. Given the lack of conserved regulation of iNOS expression in rodent and human systems, we sought to test the effect of 5-ASA on the expression of human iNOS in cultured enterocytes. Transformed human intestinal epithelial cells, DLD-1 and Caco-2BBe, were stimulated by IL-1beta and IFN-gamma and analyzed for iNOS upregulation and NO production in the presence of various aminosalicylates. 5-ASA, but not 4-ASA, dose-dependently inhibited NO production by both cell lines [IC50 (mM) DLD-1 =4.5, Caco-2BBe =2. 5]. 5-ASA also inhibited the expression of iNOS protein and mRNA and blocked cytokine-induced transcriptional upregulation of the iNOS gene. 5-ASA (1-5 mM) had no effect on cytokine-induced nuclear translocation of NF-kappaB or expression of IRF-1, transactivating factors which regulates the human iNOS enhancer. We conclude that 5-ASA inhibits iNOS expression and NO production at therapeutically relevant concentrations. The inhibition occurs at the level of transcriptional activation and is independent of IRF-1 and NF-kappaB. Since NO is an important final effector of mucosal injury in inflammatory bowel disease, these findings may have implications for the clinical efficacy of 5-ASA.
Int J Mol Med 1999 Oct
PMID:5-aminosalicylic acid inhibits iNOS transcription in human intestinal epithelial cells. 1049 88

The crystal structure of O6-methylguanine-DNA methyltransferase (EC 2.1.1.63) of hyperthermophilic archaeon Pyrococcuskodakaraensis strain KOD1 (Pk -MGMT) was determined by single isomorphous replacement method with anomalous scattering (SIRAS) at 1.8 A resolution. The archaeal protein is extremely thermostable and repairs alkylated DNA by suicidal alkyl transfer from guanine O6 to its own cysteine residue. Archaea constitute the third primary kingdom of living organisms, sharing characteristics with procaryotic and eucaryotic cells. They live in various extreme environments and are thought to include the most ancient organisms on the earth. Structural studies on hyperthermophilic archaeal proteins reveal the structural features essential for stability under the extreme environments in which these organisms live, and will provide the structural basis required for stabilizing various mesophilic proteins for industrial applications. Here, we report the crystal structure of Pk-MGMT and structural comparison of Pk-MGMT and methyltransferase homologue from Escherichia coli (AdaC, C-terminal fragment of Ada protein). Analyses of solvent-accessible surface area (SASA) reveals a large discrepancy between Pk-MGMT and AdaC with respect to the property of the ASA. In the Pk-MGMT structure, the intra-helix ion-pairs contribute to reinforce stability of alpha-helices. The inter-helix ion-pairs exist in the interior of Pk-MGMT and stabilize internal packing of tertiary structure. Furthermore, structural features of helix cappings, intra and inter-helix ion-pairs are found around the active-site structure in Pk-MGMT.
J Mol Biol 1999 Sep 24
PMID:Hyperthermostable protein structure maintained by intra and inter-helix ion-pairs in archaeal O6-methylguanine-DNA methyltransferase. 1049 33

Electron spin resonance (ESR) was used to investigate the reaction of aspirin toward reactive oxygen species, such as hydroxyl radicals (*OH), superoxide radicals (O2-) and H2O2. The Fenton reaction (Fe(II) + H2O2 ---> FE(III) + *OH + OR) was used as a source of *OH radicals. The results show that aspirin is an efficient *OH radical scavenger with a reaction rate constant of k = 3.6 x 10(10) M(-1) sec(-1), which is faster than several well established antioxidants, such as ascorbate, glutathione and cysteine. However, aspirin is not a good scavenger for O2- or H2O2. Through its antioxidant property, aspirin exhibited a protective effect against silica-induced lipid peroxidation and DNA strand breakage. Aspirin also inhibited the activation of nuclear transcription factor-kappaB induced by silica, lipopolysaccharide or the transition metal, Fe(II), as demonstrated by electrophoretic mobility shift assay. The results show that aspirin functions as an antioxidant via its ability to scavenge *OH radicals. This antioxidant property may explain some of its various physiological and pharmacological actions.
Mol Cell Biochem 1999 Sep
PMID:Antioxidant properties of aspirin: characterization of the ability of aspirin to inhibit silica-induced lipid peroxidation, DNA damage, NF-kappaB activation, and TNF-alpha production. 1054 57

Aspirin is a commonly used drug with a wide pharmacological spectrum including antiplatelet, anti-inflammatory, and neuroprotective actions. This study shows that aspirin and sodium salicylate, its major blood metabolite, reverse contractile actions of endothelin-1 (ET-1) in isolated rat aorta and human mammary arteries. They also prevent the intracellular Ca(2+) mobilizing action of ET-1 in cultured endothelial cells but not those of neuromedin B or UTP. Inhibition of the actions of ET-1 by salicylates is apparently competitive. Salicylates inhibit (125)I-ET-1 binding to recombinant rat ETA receptors. Salicylic acid promotes dissociation of (125)I-ET-1 ETA receptor complexes both in the absence and the presence of unlabeled ET-1. It has no influence on the rate of association of (125)I-ET-1 to ETA receptors. Salicylates do not promote dissociation of (125)I-ET-1 ETB receptor complexes. Salicylates potentiate relaxing actions of receptor antagonists such as bosentan. It is concluded that salicylates are allosteric inhibitors of ETA receptors. The results also suggest that: 1) irreversible ET-1 binding probably limits actions of receptor antagonists in vivo, and 2) an association of salicylates and ETA receptor antagonists should be used to evaluate the physiopathological role of ET-1 and may be of therapeutic interest in the treatment of ischemic heart disease.
Mol Pharmacol 2000 Apr
PMID:Aspirin and sodium salicylate inhibit endothelin ETA receptors by an allosteric type of mechanism. 1072 28


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