The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Gianfranco Amicosante - One of the best experts on this subject based on the ideXlab platform.
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biochemical analysis of tem 134 a new tem type extended spectrum β lactamase variant produced in a Citrobacter Koseri clinical isolate from an italian hospital
Journal of Antimicrobial Chemotherapy, 2007Co-Authors: Mariagrazia Perilli, Francesco Luzzaro, Marianna Fiore, Gian Maria Rossolini, Giuseppe Celenza, Bernardetta Segatore, Cristina Pellegrini, Gianfranco AmicosanteAbstract:OBJECTIVES: Kinetic characterization of TEM-134, a new TEM-type extended-spectrum beta-lactamase variant isolated from Citrobacter Koseri during an Italian nationwide survey. TEM-134 is a natural derivative of TEM-2 with the following substitutions: E104K, R164H and G238S. METHODS: Recombinant TEM-134 was purified from Escherichia coli HB101 (pMGP-134) by three chromatographic steps (cation-exchange chromatography, gel permeation and fast chromatofocusing). Steady-state kinetic parameters (K(m) and k(cat)) were determined by measuring substrate hydrolysis under initial rate conditions using the Hanes linearization of the Michaelis-Menten equation. Modelling was carried out using the software Modeller (version 9.1). RESULTS: TEM-134 hydrolysed with variable efficiency (k(cat)/K(m) ranging from 5 x 10(3) to 8.0 x 10(5) M(-1) . s(-1)) penicillins, narrow-spectrum cephalosporins, cefepime, cefotaxime, ceftazidime and aztreonam, which appeared to be the best substrate. Molecular modelling of the enzyme indicated that the R164H substitution may result in a compromised omega loop in TEM-134 and this may be responsible for its narrower spectrum of activity. CONCLUSIONS: Kinetic data and molecular modelling suggested that R164H has a mild detrimental effect on the global activity of the enzyme.
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novel tem type extended spectrum β lactamase tem 134 in a Citrobacter Koseri clinical isolate
Antimicrobial Agents and Chemotherapy, 2005Co-Authors: Mariagrazia Perilli, Claudia Mugnaioli, Francesco Luzzaro, Marianna Fiore, Stefania Stefani, Gian Maria Rossolini, Gianfranco AmicosanteAbstract:A new natural TEM derivative with extended-spectrum β-lactamase activity, TEM-134, was identified in a ceftazidime-resistant clinical isolate of Citrobacter Koseri. Compared to TEM-1, TEM-134 contains the following mutations: Q39K, E104K, R164H, and G238S. The blaTEM-134 gene was not transferable by conjugation and, apparently, was chromosomally encoded. Expression studies with Escherichia coli revealed efficient cefotaximase and ceftazidimase activity for TEM-134.
Mariagrazia Perilli - One of the best experts on this subject based on the ideXlab platform.
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biochemical analysis of tem 134 a new tem type extended spectrum β lactamase variant produced in a Citrobacter Koseri clinical isolate from an italian hospital
Journal of Antimicrobial Chemotherapy, 2007Co-Authors: Mariagrazia Perilli, Francesco Luzzaro, Marianna Fiore, Gian Maria Rossolini, Giuseppe Celenza, Bernardetta Segatore, Cristina Pellegrini, Gianfranco AmicosanteAbstract:OBJECTIVES: Kinetic characterization of TEM-134, a new TEM-type extended-spectrum beta-lactamase variant isolated from Citrobacter Koseri during an Italian nationwide survey. TEM-134 is a natural derivative of TEM-2 with the following substitutions: E104K, R164H and G238S. METHODS: Recombinant TEM-134 was purified from Escherichia coli HB101 (pMGP-134) by three chromatographic steps (cation-exchange chromatography, gel permeation and fast chromatofocusing). Steady-state kinetic parameters (K(m) and k(cat)) were determined by measuring substrate hydrolysis under initial rate conditions using the Hanes linearization of the Michaelis-Menten equation. Modelling was carried out using the software Modeller (version 9.1). RESULTS: TEM-134 hydrolysed with variable efficiency (k(cat)/K(m) ranging from 5 x 10(3) to 8.0 x 10(5) M(-1) . s(-1)) penicillins, narrow-spectrum cephalosporins, cefepime, cefotaxime, ceftazidime and aztreonam, which appeared to be the best substrate. Molecular modelling of the enzyme indicated that the R164H substitution may result in a compromised omega loop in TEM-134 and this may be responsible for its narrower spectrum of activity. CONCLUSIONS: Kinetic data and molecular modelling suggested that R164H has a mild detrimental effect on the global activity of the enzyme.
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novel tem type extended spectrum β lactamase tem 134 in a Citrobacter Koseri clinical isolate
Antimicrobial Agents and Chemotherapy, 2005Co-Authors: Mariagrazia Perilli, Claudia Mugnaioli, Francesco Luzzaro, Marianna Fiore, Stefania Stefani, Gian Maria Rossolini, Gianfranco AmicosanteAbstract:A new natural TEM derivative with extended-spectrum β-lactamase activity, TEM-134, was identified in a ceftazidime-resistant clinical isolate of Citrobacter Koseri. Compared to TEM-1, TEM-134 contains the following mutations: Q39K, E104K, R164H, and G238S. The blaTEM-134 gene was not transferable by conjugation and, apparently, was chromosomally encoded. Expression studies with Escherichia coli revealed efficient cefotaximase and ceftazidimase activity for TEM-134.
Gian Maria Rossolini - One of the best experts on this subject based on the ideXlab platform.
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biochemical analysis of tem 134 a new tem type extended spectrum β lactamase variant produced in a Citrobacter Koseri clinical isolate from an italian hospital
Journal of Antimicrobial Chemotherapy, 2007Co-Authors: Mariagrazia Perilli, Francesco Luzzaro, Marianna Fiore, Gian Maria Rossolini, Giuseppe Celenza, Bernardetta Segatore, Cristina Pellegrini, Gianfranco AmicosanteAbstract:OBJECTIVES: Kinetic characterization of TEM-134, a new TEM-type extended-spectrum beta-lactamase variant isolated from Citrobacter Koseri during an Italian nationwide survey. TEM-134 is a natural derivative of TEM-2 with the following substitutions: E104K, R164H and G238S. METHODS: Recombinant TEM-134 was purified from Escherichia coli HB101 (pMGP-134) by three chromatographic steps (cation-exchange chromatography, gel permeation and fast chromatofocusing). Steady-state kinetic parameters (K(m) and k(cat)) were determined by measuring substrate hydrolysis under initial rate conditions using the Hanes linearization of the Michaelis-Menten equation. Modelling was carried out using the software Modeller (version 9.1). RESULTS: TEM-134 hydrolysed with variable efficiency (k(cat)/K(m) ranging from 5 x 10(3) to 8.0 x 10(5) M(-1) . s(-1)) penicillins, narrow-spectrum cephalosporins, cefepime, cefotaxime, ceftazidime and aztreonam, which appeared to be the best substrate. Molecular modelling of the enzyme indicated that the R164H substitution may result in a compromised omega loop in TEM-134 and this may be responsible for its narrower spectrum of activity. CONCLUSIONS: Kinetic data and molecular modelling suggested that R164H has a mild detrimental effect on the global activity of the enzyme.
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novel tem type extended spectrum β lactamase tem 134 in a Citrobacter Koseri clinical isolate
Antimicrobial Agents and Chemotherapy, 2005Co-Authors: Mariagrazia Perilli, Claudia Mugnaioli, Francesco Luzzaro, Marianna Fiore, Stefania Stefani, Gian Maria Rossolini, Gianfranco AmicosanteAbstract:A new natural TEM derivative with extended-spectrum β-lactamase activity, TEM-134, was identified in a ceftazidime-resistant clinical isolate of Citrobacter Koseri. Compared to TEM-1, TEM-134 contains the following mutations: Q39K, E104K, R164H, and G238S. The blaTEM-134 gene was not transferable by conjugation and, apparently, was chromosomally encoded. Expression studies with Escherichia coli revealed efficient cefotaximase and ceftazidimase activity for TEM-134.
Francesco Luzzaro - One of the best experts on this subject based on the ideXlab platform.
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biochemical analysis of tem 134 a new tem type extended spectrum β lactamase variant produced in a Citrobacter Koseri clinical isolate from an italian hospital
Journal of Antimicrobial Chemotherapy, 2007Co-Authors: Mariagrazia Perilli, Francesco Luzzaro, Marianna Fiore, Gian Maria Rossolini, Giuseppe Celenza, Bernardetta Segatore, Cristina Pellegrini, Gianfranco AmicosanteAbstract:OBJECTIVES: Kinetic characterization of TEM-134, a new TEM-type extended-spectrum beta-lactamase variant isolated from Citrobacter Koseri during an Italian nationwide survey. TEM-134 is a natural derivative of TEM-2 with the following substitutions: E104K, R164H and G238S. METHODS: Recombinant TEM-134 was purified from Escherichia coli HB101 (pMGP-134) by three chromatographic steps (cation-exchange chromatography, gel permeation and fast chromatofocusing). Steady-state kinetic parameters (K(m) and k(cat)) were determined by measuring substrate hydrolysis under initial rate conditions using the Hanes linearization of the Michaelis-Menten equation. Modelling was carried out using the software Modeller (version 9.1). RESULTS: TEM-134 hydrolysed with variable efficiency (k(cat)/K(m) ranging from 5 x 10(3) to 8.0 x 10(5) M(-1) . s(-1)) penicillins, narrow-spectrum cephalosporins, cefepime, cefotaxime, ceftazidime and aztreonam, which appeared to be the best substrate. Molecular modelling of the enzyme indicated that the R164H substitution may result in a compromised omega loop in TEM-134 and this may be responsible for its narrower spectrum of activity. CONCLUSIONS: Kinetic data and molecular modelling suggested that R164H has a mild detrimental effect on the global activity of the enzyme.
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novel tem type extended spectrum β lactamase tem 134 in a Citrobacter Koseri clinical isolate
Antimicrobial Agents and Chemotherapy, 2005Co-Authors: Mariagrazia Perilli, Claudia Mugnaioli, Francesco Luzzaro, Marianna Fiore, Stefania Stefani, Gian Maria Rossolini, Gianfranco AmicosanteAbstract:A new natural TEM derivative with extended-spectrum β-lactamase activity, TEM-134, was identified in a ceftazidime-resistant clinical isolate of Citrobacter Koseri. Compared to TEM-1, TEM-134 contains the following mutations: Q39K, E104K, R164H, and G238S. The blaTEM-134 gene was not transferable by conjugation and, apparently, was chromosomally encoded. Expression studies with Escherichia coli revealed efficient cefotaximase and ceftazidimase activity for TEM-134.
Marianna Fiore - One of the best experts on this subject based on the ideXlab platform.
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biochemical analysis of tem 134 a new tem type extended spectrum β lactamase variant produced in a Citrobacter Koseri clinical isolate from an italian hospital
Journal of Antimicrobial Chemotherapy, 2007Co-Authors: Mariagrazia Perilli, Francesco Luzzaro, Marianna Fiore, Gian Maria Rossolini, Giuseppe Celenza, Bernardetta Segatore, Cristina Pellegrini, Gianfranco AmicosanteAbstract:OBJECTIVES: Kinetic characterization of TEM-134, a new TEM-type extended-spectrum beta-lactamase variant isolated from Citrobacter Koseri during an Italian nationwide survey. TEM-134 is a natural derivative of TEM-2 with the following substitutions: E104K, R164H and G238S. METHODS: Recombinant TEM-134 was purified from Escherichia coli HB101 (pMGP-134) by three chromatographic steps (cation-exchange chromatography, gel permeation and fast chromatofocusing). Steady-state kinetic parameters (K(m) and k(cat)) were determined by measuring substrate hydrolysis under initial rate conditions using the Hanes linearization of the Michaelis-Menten equation. Modelling was carried out using the software Modeller (version 9.1). RESULTS: TEM-134 hydrolysed with variable efficiency (k(cat)/K(m) ranging from 5 x 10(3) to 8.0 x 10(5) M(-1) . s(-1)) penicillins, narrow-spectrum cephalosporins, cefepime, cefotaxime, ceftazidime and aztreonam, which appeared to be the best substrate. Molecular modelling of the enzyme indicated that the R164H substitution may result in a compromised omega loop in TEM-134 and this may be responsible for its narrower spectrum of activity. CONCLUSIONS: Kinetic data and molecular modelling suggested that R164H has a mild detrimental effect on the global activity of the enzyme.
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novel tem type extended spectrum β lactamase tem 134 in a Citrobacter Koseri clinical isolate
Antimicrobial Agents and Chemotherapy, 2005Co-Authors: Mariagrazia Perilli, Claudia Mugnaioli, Francesco Luzzaro, Marianna Fiore, Stefania Stefani, Gian Maria Rossolini, Gianfranco AmicosanteAbstract:A new natural TEM derivative with extended-spectrum β-lactamase activity, TEM-134, was identified in a ceftazidime-resistant clinical isolate of Citrobacter Koseri. Compared to TEM-1, TEM-134 contains the following mutations: Q39K, E104K, R164H, and G238S. The blaTEM-134 gene was not transferable by conjugation and, apparently, was chromosomally encoded. Expression studies with Escherichia coli revealed efficient cefotaximase and ceftazidimase activity for TEM-134.