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steady-state kinetics of <i>Roystonea regia</i>palm tree peroxidase

Journal of Biophysical Chemistry 2012年第1期3卷 16-28页

作者： laura sánchez zamorano Nazaret Hidalgo Cuadrado Patricia Pérez Galende Manuel G. Roig Valery L. shnyrov Departamento de Química Física Facultad de Química Universidad de Salamanca Salamanca Spain

Royal palm tree peroxidase (RPTP) has been isolated to homogeneity from leaves of Roystonea regia palm trees. The enzyme purification steps included homogenization, (NH4)sO4 precipitation, extraction of palm leaf colored compounds and consecutive chromatography on Phenyl-sepharose, TsK-Gel DEAE-5PW and superdex-200. The novel peroxidase was characterized as having a molecular weight of 48.2 ± 3.0 kDa and an isoelectric point pI 5.4 ± 0.1. The enzyme forms dimers in solution with approximate molecular weight of 92 ± 2 kDa. Here we investigated the steady-state kinetic mechanism of the H2O2-supported oxidation of different organic substrates by RPTP. The results of the analysis of the initial rates vs. H2O2 and reducing substrate concentrations were seen to be consistent with a substrate-inhibited Ping-Pong Bi-Bi reaction mechanism. The phenomenological approach used expresses the peroxidase Ping-Pong mechanism in the form of the Michaelis-Menten equation and affords an interpretation of the effects in terms of the kinetic parameters KmH2O2, KmAH2, kcat, KsIH2O2, KsIAH2 and of the microscopic rate constants k1 and k3 of the shared three-step peroxidase catalytic cycle. Furthermore, the concentration and time-dependences and the mechanism of the suicide inactivation of RPTP by hydrogen peroxide were studied kinetically with guaiacol as co-substrate. The turnover number (r) of H2O2 required to complete the inactivation of the enzyme was 2154 ± 100 and the apparent rate constants of catalysis 185 s–1 and 18 s–1.

关键词： Roystonea regia Peroxidase steady-state Kinetics substrate Inhibition Mechanism-Based Inactivation Kinetics Hydrogen Peroxide

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New environmental factors related to diabetes risk in humans:Emerging bisphenols used in synthesis of plastics

引用

World Journal of Diabetes 2023年第8期14卷 1301-1313页

作者： Rafael Moreno-Gómez-Toledano María Delgado-Marín Alberto Cook-Calvete Claudia González-Cucharero Nunzio Alcharani Beatriz Jiménez-Guirado Ignacio Hernandez Rafael Ramirez-Carracedo laura Tesoro laura Botana sandra sánchez-Esteban Javier Diez-Mata Jose Luis zamorano Ricardo J.Bosch Carlos Zaragoza Marta saura Universidad de Alcalá Department of Biological Systems/PhysiologyAlcaláde Henares 28871Spain Cardiology Department University Hospital Ramón y CajalMadrid 28034Spain Laboratory of Cardiovascular Pathophysiology Joint Translational Research UnitUniversity Francisco de Vitoria School of MedicineMadrid 28034Spain Instituto Ramón y Cajal de Investigación sanitaria-IRYCIs Madrid 28034Spain

BACKGROUND Diabetes mellitus(DM)is one of the largest global health emergencies of the 21st *** recent years,its connection with environmental pollutants,such as bisphenol A(BPA),has been demonstrated;consequently,new structurally similar molecules are used to replace BPA in the plastics industry(BPs,BPF and BPAF).AIM To carry out a systematic review to allow coherent evaluation of the state of the ***,a meta-analysis was performed to unify the existing quantitative *** Firstly,a systematic review was carried out,using the terms“(bisphenol)AND(Diabetes OR Hyperglycemia)”,to maximize the number of ***,three authors analyzed the set of ***,a meta-analysis was performed for each BP,using RevMan *** addition,funnel plots were developed to study publication *** The systematic analysis of the literature revealed 13 recent articles(2017–2023)related to the study *** qualitative analysis showed interesting data linking diabetes to the three most widely used substitute BPs in the industry:BPs,BPF and ***,the meta-analysis determined a positive relationship with BPs,BPF and BPAF,which was only statistically significant with *** There is a need to apply the precautionary principle,regulating the use of new ***,replacing BPA with BPs,BPF or BPAF is unlikely to protect the population from potential health risks,such as DM.

关键词： Bisphenol s Bisphenol F Bisphenol AF Diabetes mellitus systematic review Meta-analysis

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