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Mechanistic studies on the reversible binding of nitric oxide to metmyoglobin


Mechanistic studies on the reversible binding of nitric oxide to metmyoglobin

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dc.contributor.author Laverman, Leroy E. pl
dc.contributor.author Wanat, Alicja pl
dc.contributor.author Oszajca, Janusz pl
dc.contributor.author Stochel, Grażyna [SAP11011061] pl
dc.contributor.author Ford, Peter C. pl
dc.contributor.author van Eldik, Rudi [SAP14007947] pl
dc.date.accessioned 2015-08-26T10:15:18Z
dc.date.available 2015-08-26T10:15:18Z
dc.date.issued 2001 pl
dc.identifier.issn 0002-7863 pl
dc.identifier.uri http://ruj.uj.edu.pl/xmlui/handle/item/15048
dc.language eng pl
dc.title Mechanistic studies on the reversible binding of nitric oxide to metmyoglobin pl
dc.type JournalArticle pl
dc.description.physical 285-293 pl
dc.abstract.en The ferriheme protein metmyoglobin (metMb) in buffer solution at physiological pH 7.4 reversibly binds the biomessenger molecule nitric oxide to yield the nitrosyl adduct (metMb(NO)). The kinetics of the association and dissociation processes were investigated by both laser flash photolysis and stopped-flow kinetics techniques at ambient and high pressure, in three laboratories using several different sources of metMb. The activation parameters ¢ H q , ¢ S q , and ¢ V q were calculated from the kinetic effects of varying temperature and hydrostatic pressure. For the “on” reaction of metMb plus NO, reasonable agreement was found between the various techniques with ¢ H on q , ¢ S on q , and ¢ V on q determined to have the respective values 65 kJ mol - 1 , 60 J mol - 1 K - 1 , and 20 cm 3 mol - 1 . The large and positive ¢ S q and ¢ V q values are consistent with the operation of a limiting dissociative ligand substitution mechanism whereby dissociation of the H 2 O occupying the sixth distal coordination site of metMb must precede formation of the Fe - NO bond. While the activation enthalpies of the “off” reaction displayed reasonable agreement between the various techniques (ranging from 68 to 83 kJ mol - 1 ), poorer agreement was found for the ¢ S off q values. For this reason, the kinetics for the “off” reaction were determined more directly via NO trapping experiments, which gave the respective activation parameters ¢ H off q ) 76 kJ mol - 1 , ¢ S off q ) 41 J mol - 1 K - 1 , and ¢ V off q ) 20 cm 3 mol - 1 ), again consistent with a limiting dissociative mechanism. These results are discussed in reference to other investigations of the reactions of NO with both model systems and metalloproteins. pl
dc.description.volume 123 pl
dc.description.number 2 pl
dc.identifier.doi 10.1021/ja001696z pl
dc.identifier.eissn 1520-5126 pl
dc.title.journal Journal of the American Chemical Society pl
dc.language.container eng pl
dc.affiliation Wydział Chemii : Zakład Chemii Nieorganicznej pl
dc.subtype Article pl

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