The binding of NO and CO to chelated protoheme-L-histidine methyl ester (HM-H), protoheme-glycyl-L-histidine methyl ester (HM-GH), and free protoheme (HM) has been studied in methanol-DMSO solution. In all cases, the NO adducts are five-coordinated indicating that binding of NO occurs with displacement of the axial base and confirms the strong negative trans effect exerted by NO in heme complexes, though it is found that the presence of strain in the iron-histidine bond of HM-H has a positive influence on NO binding, making it thermodynamically more favorable than for HM-GH. The equilibrium constants thus decrease in the series HM>HM-H>HM-GH. In contrast to NO, CO has a positive trans effect, and therefore, an opposite trend is observed in the binding of this ligand to the heme complexes

Effect of strain in the proximal ligand on the binding of nitric oxide and carbon monoxide to chelated protoheme complexes / M. Gullotti, L. Santagostini, E. Monzani, L. Casella. - In: INORGANIC CHEMISTRY. - ISSN 0020-1669. - 46:21(2007), pp. 8971-8975. [10.1021/ic700852c]

Effect of strain in the proximal ligand on the binding of nitric oxide and carbon monoxide to chelated protoheme complexes

M. Gullotti
Primo
;
L. Santagostini
Secondo
;
2007

Abstract

The binding of NO and CO to chelated protoheme-L-histidine methyl ester (HM-H), protoheme-glycyl-L-histidine methyl ester (HM-GH), and free protoheme (HM) has been studied in methanol-DMSO solution. In all cases, the NO adducts are five-coordinated indicating that binding of NO occurs with displacement of the axial base and confirms the strong negative trans effect exerted by NO in heme complexes, though it is found that the presence of strain in the iron-histidine bond of HM-H has a positive influence on NO binding, making it thermodynamically more favorable than for HM-GH. The equilibrium constants thus decrease in the series HM>HM-H>HM-GH. In contrast to NO, CO has a positive trans effect, and therefore, an opposite trend is observed in the binding of this ligand to the heme complexes
Settore CHIM/01 - Chimica Analitica
http://pubs.acs.org/cgi-bin/article.cgi/inocaj/2007/46/i21/pdf/ic700852c.pdf
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/39782
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