Nitrite binding to metmyoglobin and methemoglobin in comparison to nitric oxide binding

doi:10.1007/s007750100284

Nitrite binding to metmyoglobin and methemoglobin ...

Bibliographic description

title:	Nitrite binding to metmyoglobin and methemoglobin in comparison to nitric oxide binding
author:	Wanat Alicja, Gdula-Argasińska Joanna , Rutkowska-Żbik Dorota, Witko Małgorzata, Stochel Grażyna , van Eldik Rudi
Journal title:	JBIC. Journal of Biological Inorganic Chemistry
volume:	7
issue:	1-2
date of publication:	2002
pages:	165-176
ISSN:	0949-8257
eISSN:	1432-1327
DOI:	10.1007/s007750100284
language:	English
Journal language:	English
abstract in english:	Nitrite binds reversibly to the ferriheme pro- teins metmyoglobin and methemoglobin in aqueous bu er solution at a physiological pH of 7.4. The spectral changes recorded for the formation of metMb2NO 2 ) di er signi®cantly from those observed for the nitrosy- lation of metMb, which can be accounted for in terms of the di erent reaction products. Nitric oxide binding to metMb produces a nitrosyl product with Fe2II)-NO + character, whereas the reaction with nitrite produces an Fe2III)-NO 2 ± complex. The kinetics of the binding and release of nitrite by metMb and metHb were investigated by stopped- ̄ow techniques at ambient and high pres- sure. The kinetic traces recorded for the reaction of ni- trite with metMb exhibit excellent single-exponential ®ts, whereas nitrite binding to metHb is characterized by double-exponential kinetics which were assigned to the reactions of the a -and b -chains of metHb with NO 2 . The rate constants for the binding of nitrite to metMb and metHb were found to be much smaller than those reported for the binding of NO, such that nitrite impu- rities will not a ect the latter reaction. The activation parameters 2 D H 6 ; D S ne ; D V 6 ) obtained from the tem- perature and pressure dependence of the reactions sup- port the operation of a dissociative mechanism for the binding and release of nitrite, similar to that found for the binding and release of NO in metMb.
affiliation:	Wydział Chemii : Zakład Chemii Nieorganicznej
type:	journal article
subtype:	academic paper