Irina Babaligea - Academia.edu (original) (raw)
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Papers by Irina Babaligea
Bioprocess and Biosystems Engineering, 2008
Possible reaction pathways that may lead to horseradish peroxidase inactivation during the aerobi... more Possible reaction pathways that may lead to horseradish peroxidase inactivation during the aerobic oxidation of 2-aminophenol were investigated using extended kinetic curves. A kinetic model involving the formation of a low-reactive species, Compound III, was proposed and several rate constants were calculated using an optimisation computing program. Sensitivity analysis allowed to conclude that both oxidase and peroxidase cycles occur in 2-aminophenol oxidation.
A kinetic model able to adequately describe the accumulation of p-topaquinone in peroxidase-media... more A kinetic model able to adequately describe the accumulation of p-topaquinone in peroxidase-mediated oxidation of l-dopa was developed, and the rate constants for both enzymatic and non-enzymatic branch were estimated either experimentally or using a computing program for detailed kinetic simulation. It is demonstrated that the accumulation of p-topaquinone in significant amounts occurred in excess of hydrogen peroxide or during auto-oxidation of l-dopa, but changes in the ratio of initial concentrations of the reactants can reduce considerably the production of this intermediate.
Bioprocess and Biosystems Engineering, 2008
Possible reaction pathways that may lead to horseradish peroxidase inactivation during the aerobi... more Possible reaction pathways that may lead to horseradish peroxidase inactivation during the aerobic oxidation of 2-aminophenol were investigated using extended kinetic curves. A kinetic model involving the formation of a low-reactive species, Compound III, was proposed and several rate constants were calculated using an optimisation computing program. Sensitivity analysis allowed to conclude that both oxidase and peroxidase cycles occur in 2-aminophenol oxidation.
Bioprocess and Biosystems Engineering, 2008
Possible reaction pathways that may lead to horseradish peroxidase inactivation during the aerobi... more Possible reaction pathways that may lead to horseradish peroxidase inactivation during the aerobic oxidation of 2-aminophenol were investigated using extended kinetic curves. A kinetic model involving the formation of a low-reactive species, Compound III, was proposed and several rate constants were calculated using an optimisation computing program. Sensitivity analysis allowed to conclude that both oxidase and peroxidase cycles occur in 2-aminophenol oxidation.
Biochemical Engineering Journal, 2010
A kinetic model able to adequately describe the accumulation of p-topaquinone in peroxidase-media... more A kinetic model able to adequately describe the accumulation of p-topaquinone in peroxidase-mediated oxidation of l-dopa was developed, and the rate constants for both enzymatic and non-enzymatic branch were estimated either experimentally or using a computing program for detailed kinetic simulation. It is demonstrated that the accumulation of p-topaquinone in significant amounts occurred in excess of hydrogen peroxide or during auto-oxidation of l-dopa, but changes in the ratio of initial concentrations of the reactants can reduce considerably the production of this intermediate.
Chemical Engineering & Technology, 2010
Kinetic parameters of operational inactivation of horseradish peroxidase during the enzymatic oxi... more Kinetic parameters of operational inactivation of horseradish peroxidase during the enzymatic oxidation of 2-aminophenol with hydrogen peroxide were estimated using an isoconversional method. This method only requires the progress kinetic curves obtained at constant initial concentrations of the substrates. In order to investigate the possible pathways of low-reactive species compound III formation, a kinetic model was proposed and several rate constants were calculated using an optimization computing program. Generation of an oxygen reactive species in the reaction system was also considered in the reaction scheme. Sensitivity analysis, corroborated with the overall inactivation kinetics observed with the isoconversional method, allows the conclusion that the inactivation of the enzyme occurs mainly via the reaction of compound II with hydrogen peroxide.
Chemical Engineering & Technology, 2010
Kinetic parameters of operational inactivation of horseradish peroxidase during the enzymatic oxi... more Kinetic parameters of operational inactivation of horseradish peroxidase during the enzymatic oxidation of 2-aminophenol with hydrogen peroxide were estimated using an isoconversional method. This method only requires the progress kinetic curves obtained at constant initial concentrations of the substrates. In order to investigate the possible pathways of low-reactive species compound III formation, a kinetic model was proposed and several rate constants were calculated using an optimization computing program. Generation of an oxygen reactive species in the reaction system was also considered in the reaction scheme. Sensitivity analysis, corroborated with the overall inactivation kinetics observed with the isoconversional method, allows the conclusion that the inactivation of the enzyme occurs mainly via the reaction of compound II with hydrogen peroxide.
Chemical Engineering & Technology, 2010
Kinetic parameters of operational inactivation of horseradish peroxidase during the enzymatic oxi... more Kinetic parameters of operational inactivation of horseradish peroxidase during the enzymatic oxidation of 2-aminophenol with hydrogen peroxide were estimated using an isoconversional method. This method only requires the progress kinetic curves obtained at constant initial concentrations of the substrates. In order to investigate the possible pathways of low-reactive species compound III formation, a kinetic model was proposed and several rate constants were calculated using an optimization computing program. Generation of an oxygen reactive species in the reaction system was also considered in the reaction scheme. Sensitivity analysis, corroborated with the overall inactivation kinetics observed with the isoconversional method, allows the conclusion that the inactivation of the enzyme occurs mainly via the reaction of compound II with hydrogen peroxide. Figure 7. Experimental and simulated kinetic curves according to the proposed model; [OAP] 0 = 1 · 10 -4 M, [H 2 O 2 ] = 2.5 · 10 -5 M.
Bioprocess and Biosystems Engineering, 2008
Possible reaction pathways that may lead to horseradish peroxidase inactivation during the aerobi... more Possible reaction pathways that may lead to horseradish peroxidase inactivation during the aerobic oxidation of 2-aminophenol were investigated using extended kinetic curves. A kinetic model involving the formation of a low-reactive species, Compound III, was proposed and several rate constants were calculated using an optimisation computing program. Sensitivity analysis allowed to conclude that both oxidase and peroxidase cycles occur in 2-aminophenol oxidation.
Biochemical Engineering Journal, 2010
A kinetic model able to adequately describe the accumulation of p-topaquinone in peroxidase-media... more A kinetic model able to adequately describe the accumulation of p-topaquinone in peroxidase-mediated oxidation of l-dopa was developed, and the rate constants for both enzymatic and non-enzymatic branch were estimated either experimentally or using a computing program for detailed kinetic simulation. It is demonstrated that the accumulation of p-topaquinone in significant amounts occurred in excess of hydrogen peroxide or during auto-oxidation of l-dopa, but changes in the ratio of initial concentrations of the reactants can reduce considerably the production of this intermediate.
Applied Catalysis A: General, 2012
The catalytic oxidation of 2-aminophenol (OAP) to 2-amino-3H-phenoxazin-3-one (APX, Questiomycin ... more The catalytic oxidation of 2-aminophenol (OAP) to 2-amino-3H-phenoxazin-3-one (APX, Questiomycin A) was the object of numerous studies partly due to antimicrobial properties of Questiomycin A and mostly because it can be used as a model for the synthesis of the naturally occurring antineoplastic agent Actinomycin D. Several copper complexes were used as dioxygen and/or substrates activators in order to mimic the activity of phenoxazinone synthase, but the reported assays failed to provide reasonable mechanistic features in media compatible with natural conditions. The main purposes of our work were to use simple copper salts to perform oxidation of OAP in oxygenated aqueous solutions and to develop a reaction scheme able to explain the low yields in APX along with the operational inactivation of the catalyst. A 11-step kinetic model able to describe the inactivation of copper(II) catalyst during oxidation of OAP to APX in oxygenated solutions was developed, and the rate constants for both catalytic and noncatalytic branch were estimated either experimentally or using a computing program for detailed kinetic simulation. It was demonstrated that the inactivation path can be assigned to formation of the stable bis(o-iminosemiquinonato)copper(II) complex, a compound reported as a moderate antimicrobial agent.
Bioprocess and Biosystems Engineering, 2008
Possible reaction pathways that may lead to horseradish peroxidase inactivation during the aerobi... more Possible reaction pathways that may lead to horseradish peroxidase inactivation during the aerobic oxidation of 2-aminophenol were investigated using extended kinetic curves. A kinetic model involving the formation of a low-reactive species, Compound III, was proposed and several rate constants were calculated using an optimisation computing program. Sensitivity analysis allowed to conclude that both oxidase and peroxidase cycles occur in 2-aminophenol oxidation.
A kinetic model able to adequately describe the accumulation of p-topaquinone in peroxidase-media... more A kinetic model able to adequately describe the accumulation of p-topaquinone in peroxidase-mediated oxidation of l-dopa was developed, and the rate constants for both enzymatic and non-enzymatic branch were estimated either experimentally or using a computing program for detailed kinetic simulation. It is demonstrated that the accumulation of p-topaquinone in significant amounts occurred in excess of hydrogen peroxide or during auto-oxidation of l-dopa, but changes in the ratio of initial concentrations of the reactants can reduce considerably the production of this intermediate.
Bioprocess and Biosystems Engineering, 2008
Possible reaction pathways that may lead to horseradish peroxidase inactivation during the aerobi... more Possible reaction pathways that may lead to horseradish peroxidase inactivation during the aerobic oxidation of 2-aminophenol were investigated using extended kinetic curves. A kinetic model involving the formation of a low-reactive species, Compound III, was proposed and several rate constants were calculated using an optimisation computing program. Sensitivity analysis allowed to conclude that both oxidase and peroxidase cycles occur in 2-aminophenol oxidation.
Bioprocess and Biosystems Engineering, 2008
Possible reaction pathways that may lead to horseradish peroxidase inactivation during the aerobi... more Possible reaction pathways that may lead to horseradish peroxidase inactivation during the aerobic oxidation of 2-aminophenol were investigated using extended kinetic curves. A kinetic model involving the formation of a low-reactive species, Compound III, was proposed and several rate constants were calculated using an optimisation computing program. Sensitivity analysis allowed to conclude that both oxidase and peroxidase cycles occur in 2-aminophenol oxidation.
Biochemical Engineering Journal, 2010
A kinetic model able to adequately describe the accumulation of p-topaquinone in peroxidase-media... more A kinetic model able to adequately describe the accumulation of p-topaquinone in peroxidase-mediated oxidation of l-dopa was developed, and the rate constants for both enzymatic and non-enzymatic branch were estimated either experimentally or using a computing program for detailed kinetic simulation. It is demonstrated that the accumulation of p-topaquinone in significant amounts occurred in excess of hydrogen peroxide or during auto-oxidation of l-dopa, but changes in the ratio of initial concentrations of the reactants can reduce considerably the production of this intermediate.
Chemical Engineering & Technology, 2010
Kinetic parameters of operational inactivation of horseradish peroxidase during the enzymatic oxi... more Kinetic parameters of operational inactivation of horseradish peroxidase during the enzymatic oxidation of 2-aminophenol with hydrogen peroxide were estimated using an isoconversional method. This method only requires the progress kinetic curves obtained at constant initial concentrations of the substrates. In order to investigate the possible pathways of low-reactive species compound III formation, a kinetic model was proposed and several rate constants were calculated using an optimization computing program. Generation of an oxygen reactive species in the reaction system was also considered in the reaction scheme. Sensitivity analysis, corroborated with the overall inactivation kinetics observed with the isoconversional method, allows the conclusion that the inactivation of the enzyme occurs mainly via the reaction of compound II with hydrogen peroxide.
Chemical Engineering & Technology, 2010
Kinetic parameters of operational inactivation of horseradish peroxidase during the enzymatic oxi... more Kinetic parameters of operational inactivation of horseradish peroxidase during the enzymatic oxidation of 2-aminophenol with hydrogen peroxide were estimated using an isoconversional method. This method only requires the progress kinetic curves obtained at constant initial concentrations of the substrates. In order to investigate the possible pathways of low-reactive species compound III formation, a kinetic model was proposed and several rate constants were calculated using an optimization computing program. Generation of an oxygen reactive species in the reaction system was also considered in the reaction scheme. Sensitivity analysis, corroborated with the overall inactivation kinetics observed with the isoconversional method, allows the conclusion that the inactivation of the enzyme occurs mainly via the reaction of compound II with hydrogen peroxide.
Chemical Engineering & Technology, 2010
Kinetic parameters of operational inactivation of horseradish peroxidase during the enzymatic oxi... more Kinetic parameters of operational inactivation of horseradish peroxidase during the enzymatic oxidation of 2-aminophenol with hydrogen peroxide were estimated using an isoconversional method. This method only requires the progress kinetic curves obtained at constant initial concentrations of the substrates. In order to investigate the possible pathways of low-reactive species compound III formation, a kinetic model was proposed and several rate constants were calculated using an optimization computing program. Generation of an oxygen reactive species in the reaction system was also considered in the reaction scheme. Sensitivity analysis, corroborated with the overall inactivation kinetics observed with the isoconversional method, allows the conclusion that the inactivation of the enzyme occurs mainly via the reaction of compound II with hydrogen peroxide. Figure 7. Experimental and simulated kinetic curves according to the proposed model; [OAP] 0 = 1 · 10 -4 M, [H 2 O 2 ] = 2.5 · 10 -5 M.
Bioprocess and Biosystems Engineering, 2008
Possible reaction pathways that may lead to horseradish peroxidase inactivation during the aerobi... more Possible reaction pathways that may lead to horseradish peroxidase inactivation during the aerobic oxidation of 2-aminophenol were investigated using extended kinetic curves. A kinetic model involving the formation of a low-reactive species, Compound III, was proposed and several rate constants were calculated using an optimisation computing program. Sensitivity analysis allowed to conclude that both oxidase and peroxidase cycles occur in 2-aminophenol oxidation.
Biochemical Engineering Journal, 2010
A kinetic model able to adequately describe the accumulation of p-topaquinone in peroxidase-media... more A kinetic model able to adequately describe the accumulation of p-topaquinone in peroxidase-mediated oxidation of l-dopa was developed, and the rate constants for both enzymatic and non-enzymatic branch were estimated either experimentally or using a computing program for detailed kinetic simulation. It is demonstrated that the accumulation of p-topaquinone in significant amounts occurred in excess of hydrogen peroxide or during auto-oxidation of l-dopa, but changes in the ratio of initial concentrations of the reactants can reduce considerably the production of this intermediate.
Applied Catalysis A: General, 2012
The catalytic oxidation of 2-aminophenol (OAP) to 2-amino-3H-phenoxazin-3-one (APX, Questiomycin ... more The catalytic oxidation of 2-aminophenol (OAP) to 2-amino-3H-phenoxazin-3-one (APX, Questiomycin A) was the object of numerous studies partly due to antimicrobial properties of Questiomycin A and mostly because it can be used as a model for the synthesis of the naturally occurring antineoplastic agent Actinomycin D. Several copper complexes were used as dioxygen and/or substrates activators in order to mimic the activity of phenoxazinone synthase, but the reported assays failed to provide reasonable mechanistic features in media compatible with natural conditions. The main purposes of our work were to use simple copper salts to perform oxidation of OAP in oxygenated aqueous solutions and to develop a reaction scheme able to explain the low yields in APX along with the operational inactivation of the catalyst. A 11-step kinetic model able to describe the inactivation of copper(II) catalyst during oxidation of OAP to APX in oxygenated solutions was developed, and the rate constants for both catalytic and noncatalytic branch were estimated either experimentally or using a computing program for detailed kinetic simulation. It was demonstrated that the inactivation path can be assigned to formation of the stable bis(o-iminosemiquinonato)copper(II) complex, a compound reported as a moderate antimicrobial agent.