The Experts below are selected from a list of 210 Experts worldwide ranked by ideXlab platform
José Daniel Figueroa-villar - One of the best experts on this subject based on the ideXlab platform.
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Homology modeling of wild type and pyrimethamine/cycloguanil-cross Resistant Mutant type Plasmodium falciparum dihydrofolate reductase. A model for antimalarial chemotherapy resistance
Biophysical Chemistry, 2001Co-Authors: Osvaldo Andrade Santos Filho, Ricardo Bicca De Alencastro, José Daniel Figueroa-villarAbstract:Abstract We propose a low-resolution model for both the wild type and the pyrimethamine (Pyr)/cycloguanil (Cyc) cross-Resistant Mutant type Plasmodium falciparum DHFR (PfDHFR), based on homology modeling using chicken liver DHFR as a template. The built models contain five α-helices, eight β-sheets, eight tight turns and several loops. The Ramachandran plot for the models shows 95.3 and 100% of the amino acid residues in the favorable regions for the whole enzymes and for the active sites, respectively. Furthermore, we made a preliminary analysis of the complexes Pyr/Cyc-wild DHFR and Pyr/Cyc-Mutant DHFR in order to explain the probable mechanism of resistance. Our results show that the steric factor may be the main structural cause of P. falciparum resistance toward antifolate drugs.
Jose Daniel Figueroavillar - One of the best experts on this subject based on the ideXlab platform.
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homology modeling of wild type and pyrimethamine cycloguanil cross Resistant Mutant type plasmodium falciparum dihydrofolate reductase a model for antimalarial chemotherapy resistance
Biophysical Chemistry, 2001Co-Authors: Osvaldo A Santosfilho, Ricardo Bicca De Alencastro, Jose Daniel FigueroavillarAbstract:Abstract We propose a low-resolution model for both the wild type and the pyrimethamine (Pyr)/cycloguanil (Cyc) cross-Resistant Mutant type Plasmodium falciparum DHFR (PfDHFR), based on homology modeling using chicken liver DHFR as a template. The built models contain five α-helices, eight β-sheets, eight tight turns and several loops. The Ramachandran plot for the models shows 95.3 and 100% of the amino acid residues in the favorable regions for the whole enzymes and for the active sites, respectively. Furthermore, we made a preliminary analysis of the complexes Pyr/Cyc-wild DHFR and Pyr/Cyc-Mutant DHFR in order to explain the probable mechanism of resistance. Our results show that the steric factor may be the main structural cause of P. falciparum resistance toward antifolate drugs.
Ricardo Bicca De Alencastro - One of the best experts on this subject based on the ideXlab platform.
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homology modeling of wild type and pyrimethamine cycloguanil cross Resistant Mutant type plasmodium falciparum dihydrofolate reductase a model for antimalarial chemotherapy resistance
Biophysical Chemistry, 2001Co-Authors: Osvaldo A Santosfilho, Ricardo Bicca De Alencastro, Jose Daniel FigueroavillarAbstract:Abstract We propose a low-resolution model for both the wild type and the pyrimethamine (Pyr)/cycloguanil (Cyc) cross-Resistant Mutant type Plasmodium falciparum DHFR (PfDHFR), based on homology modeling using chicken liver DHFR as a template. The built models contain five α-helices, eight β-sheets, eight tight turns and several loops. The Ramachandran plot for the models shows 95.3 and 100% of the amino acid residues in the favorable regions for the whole enzymes and for the active sites, respectively. Furthermore, we made a preliminary analysis of the complexes Pyr/Cyc-wild DHFR and Pyr/Cyc-Mutant DHFR in order to explain the probable mechanism of resistance. Our results show that the steric factor may be the main structural cause of P. falciparum resistance toward antifolate drugs.
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Homology modeling of wild type and pyrimethamine/cycloguanil-cross Resistant Mutant type Plasmodium falciparum dihydrofolate reductase. A model for antimalarial chemotherapy resistance
Biophysical Chemistry, 2001Co-Authors: Osvaldo Andrade Santos Filho, Ricardo Bicca De Alencastro, José Daniel Figueroa-villarAbstract:Abstract We propose a low-resolution model for both the wild type and the pyrimethamine (Pyr)/cycloguanil (Cyc) cross-Resistant Mutant type Plasmodium falciparum DHFR (PfDHFR), based on homology modeling using chicken liver DHFR as a template. The built models contain five α-helices, eight β-sheets, eight tight turns and several loops. The Ramachandran plot for the models shows 95.3 and 100% of the amino acid residues in the favorable regions for the whole enzymes and for the active sites, respectively. Furthermore, we made a preliminary analysis of the complexes Pyr/Cyc-wild DHFR and Pyr/Cyc-Mutant DHFR in order to explain the probable mechanism of resistance. Our results show that the steric factor may be the main structural cause of P. falciparum resistance toward antifolate drugs.
A Tomasz - One of the best experts on this subject based on the ideXlab platform.
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inhibition of cell wall turnover and autolysis by vancomycin in a highly vancomycin Resistant Mutant of staphylococcus aureus
Journal of Bacteriology, 1997Co-Authors: Krzysztof Sieradzki, A TomaszAbstract:A highly vancomycin-Resistant Mutant (MIC = 100 microg/ml) of Staphylococcus aureus, Mutant VM, which was isolated in the laboratory by a step-pressure procedure, continued to grow and synthesize peptidoglycan in the presence of vancomycin (50 microg/ml) in the medium, but the antibiotic completely inhibited cell wall turnover and autolysis, resulting in the accumulation of cell wall material at the cell surface and inhibition of daughter cell separation. Cultures of Mutant VM removed vancomycin from the growth medium through binding the antibiotic to the cell walls, from which the antibiotic could be quantitatively recovered in biologically active form. Vancomycin blocked the in vitro hydrolysis of cell walls by autolytic enzyme extracts, lysostaphin and mutanolysin. Analysis of UDP-linked peptidoglycan precursors showed no evidence for the presence of D-lactate-terminating muropeptides. While there was no significant difference in the composition of muropeptide units of Mutant and parental cell walls, the peptidoglycan of VM had a significantly lower degree of cross-linkage. These observations and the results of vancomycin-binding studies suggest alterations in the structural organization of the Mutant cell walls such that access of the vancomycin molecules to the sites of wall biosynthesis is blocked.
Yoshinobu Matsumura - One of the best experts on this subject based on the ideXlab platform.
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All genomic mutations in the antimicrobial surfactant-Resistant Mutant, Escherichia coli OW66, are involved in cell resistance to surfactant
Applied Microbiology and Biotechnology, 2010Co-Authors: Kunihiro Nakata, Myo Myoung Koh, Tetsuaki Tsuchido, Yoshinobu MatsumuraAbstract:The spontaneous antimicrobial surfactant-Resistant Mutant, Escherichia coli OW66, has been isolated, and its physiological properties have been characterized in our previous paper (Ishikawa et al., J Appl Microbiol 92:261–268, 2002b ). This report revealed that strain OW66 had seven mutations in their chromosomal DNA by comparative genomic hybridization microarray, and that their alternative functions were involved in cell resistance to antimicrobial surfactants. These mutations were located in oppB , ydcR , IVR( vacJ - yfdC ), rpoN , rpoB , rpoC , and soxR . Furthermore, seven of the single-mutated isogenic strains and seven of the six-mutated isogenic strains were constructed from strains OW6 (NBRC106482) and OW66, respectively, through homologous recombination, and their resistances to an antimicrobial surfactant were measured using the minimum inhibitory concentration method. These results revealed that all six-mutated strains were more sensitive than strain OW66, and that the soxR66 mutation was independently involved in antimicrobial surfactant resistance of E. coli cells. Expression of soxR66 and soxS was increased in both strains OW66 and OW6- soxR66 without the surfactant treatment by the quantitative real time-polymerase chain reaction analysis, compared with strain OW6. Two-dimensional polyacrylamide gel electrophoresis analysis also revealed that some proteins in the soxRS regulon, including Mn-SOD, were overexpressed in both strains OW66 and OW6- soxR66 . These results indicate that the soxR66 mutation leads to the constitutive expression of the soxRS regulon, resulting in the acquired resistance of E. coli cells to an antimicrobial surfactant.
