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Spectroscopic and Kinetic Evidence for the Crucial Role of Compound 0 in the P450cam‐Catalyzed Hydroxylation of Camphor by Hydrogen Peroxide 下载免费PDF全文
Dr. Alicja Franke Prof. Dr. Rudi van Eldik 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(43):15201-15210
The hydroperoxo iron(III) intermediate P450camFeIII–OOH, being the true Compound 0 (Cpd 0) involved in the natural catalytic cycle of P450cam, could be transiently observed in the peroxo‐shunt oxidation of the substrate‐free enzyme by hydrogen peroxide under mild basic conditions and low temperature. The prolonged lifetime of Cpd 0 enabled us to kinetically examine the formation and reactivity of P450camFeIII–OOH species as a function of varying reaction conditions, such as pH, and concentration of H2O2, camphor, and potassium ions. The mechanism of hydrogen peroxide binding to the substrate‐free form of P450cam differs completely from that observed for other heme proteins possessing the distal histidine as a general acid–base catalyst and is mainly governed by the ability of H2O2 to undergo deprotonation at the hydroxo ligand coordinated to the iron(III) center under conditions of pH≥p${K{{{\rm P450}\hfill \atop {\rm a}\hfill}}}$ . Notably, no spectroscopic evidence for the formation of either Cpd I or Cpd II as products of heterolytic or homolytic O?O bond cleavage, respectively, in Cpd 0 could be observed under the selected reaction conditions. The kinetic data obtained from the reactivity studies involving (1R)‐camphor, provide, for the first time, experimental evidence for the catalytic activity of the P450FeIII–OOH intermediate in the oxidation of the natural substrate of P450cam. 相似文献
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Magdalena Rudowska Robert Wieczorek Alicja Kluczyk Piotr Stefanowicz Zbigniew Szewczuk 《Journal of the American Society for Mass Spectrometry》2013,24(6):846-856
The fragmentation of peptides containing quaternary ammonium group, but lacking easily mobilizable protons, was examined with the aid of deuterium-labeled analogs and quantum-chemical modeling. The fragmentation of oligoproline containing quaternary ammonium group involves the mobilization of hydrogens localized at α- and γ- or δ-carbon atoms in the pyrrolidine ring of proline. The study of the dissociation pattern highlights the unusual proline residue behavior during MS/MS experiments of peptides. 相似文献
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Alicja Boryło Bogdan Skwarzec Grzegorz Romańczyk Janusz Siebert 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(3):1685-1691
The determination of polonium 210Po in human blood samples is presented and discussed in this paper. The human blood samples were collected from patients of Medical University of Gdańsk with ischaemic heart disease (morbus ischaemicus cordis, MIC). The polonium concentrations in analyzed human blood samples are very differentiated. 210Po is of particular interest in public health and although is present in the environment in extremely low amounts, it is easily bioaccumulated to the human body. The study shows that the amount of 210Po that is incorporated into the human body depends on the food habits and some difference in its levels could be observed between smokers and non-smokers. 相似文献
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Marek Biziuk Edmund Kozłowski Alicja Błasiak 《International journal of environmental analytical chemistry》2013,93(3):147-151
Abstract The present method is based on preconcentration of organic contaminants on XAD-4 as sorbent, thermal desorption, mineralization and coulometric argentometric titration for the final determination of halides. The results were calculated as the total parameter VOX (volatile organic halogen) expressed as chlorine. The method has been used for the VOX determination in tap water, Vistula river water and Baltic Sea water. Sampling of the Baltic Sea water has been carried out during the research cruise of the r/v ‘Oceania’. The relatively high anthropogenic pollution of the river Vistula (c vox = 11–45 μg Cl/cd3), Gulf of Gdańsk (c vox = 0.6–4.5 μg Cl/dm3) and the Pomerania Bay (c vox = 2 μg Cl/dm3) has been determined. The VOX concentration in the tap water varied between 13 and 56 μg/dm3; that is, this water is seriously polluted by volatile organic halogen compounds. 相似文献
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