The pH dependence of redox properties, spectroscopic features and CO binding kinetics for the chelated protohemin-6(7)-L-histidine methyl ester (heme-H) and the chelated protohemin-6(7)-glycyl-L-histidine methyl ester (heme-GH) systems has been investigated between pH 2.0 and 12.0. The two heme systems appear to be modulated by four protonating groups, tentatively identified as coordinated H2O, one of heme's propionates, N epsilon of the coordinating imidazole, and the carboxylate of the histidine residue upon hydrolysis of the methyl ester group (in acid medium). The pK(a) values are different for the two hemes, thus reflecting structural differences. In particular, the different strain at the Fe-N-epsilon bond, related to the different length of the coordinating arm, results in a dramatic alteration of the bond strength, which is much smaller in heme-H than in heme-GH. It leads to a variation in the variation of the pKa for the protonation of the N-epsilon of the axial imidazole as well as in the proton-linked behavior of the other protonating groups, envisaging a cross-talk communication mechanism among different groups of the heme, which can be operative and relevant also in the presence of the protein matrix.

De Sanctis, G., Fasciglione, G., Marini, S., Sinibaldi, F., Santucci, R., Monzani, E., et al. (2006). pH-dependent redox and CO binding properties of chelated protoheme-L-histidine and protoheme-glycyl-L-histidine complexes. JBIC, 11(2), 153-167 [10.1007/s00775-005-0060-y].

pH-dependent redox and CO binding properties of chelated protoheme-L-histidine and protoheme-glycyl-L-histidine complexes

FASCIGLIONE, GIOVANNI;MARINI, STEFANO;SINIBALDI, FEDERICA;SANTUCCI, ROBERTO;COLETTA, MASSIMILIANO
2006-03-01

Abstract

The pH dependence of redox properties, spectroscopic features and CO binding kinetics for the chelated protohemin-6(7)-L-histidine methyl ester (heme-H) and the chelated protohemin-6(7)-glycyl-L-histidine methyl ester (heme-GH) systems has been investigated between pH 2.0 and 12.0. The two heme systems appear to be modulated by four protonating groups, tentatively identified as coordinated H2O, one of heme's propionates, N epsilon of the coordinating imidazole, and the carboxylate of the histidine residue upon hydrolysis of the methyl ester group (in acid medium). The pK(a) values are different for the two hemes, thus reflecting structural differences. In particular, the different strain at the Fe-N-epsilon bond, related to the different length of the coordinating arm, results in a dramatic alteration of the bond strength, which is much smaller in heme-H than in heme-GH. It leads to a variation in the variation of the pKa for the protonation of the N-epsilon of the axial imidazole as well as in the proton-linked behavior of the other protonating groups, envisaging a cross-talk communication mechanism among different groups of the heme, which can be operative and relevant also in the presence of the protein matrix.
mar-2006
Pubblicato
Rilevanza internazionale
Articolo
Esperti anonimi
Settore BIO/10 - BIOCHIMICA
English
Con Impact Factor ISI
Absorption spectra; CO binding kinetics; Heme model systems; pH dependence; Redox properties
De Sanctis, G., Fasciglione, G., Marini, S., Sinibaldi, F., Santucci, R., Monzani, E., et al. (2006). pH-dependent redox and CO binding properties of chelated protoheme-L-histidine and protoheme-glycyl-L-histidine complexes. JBIC, 11(2), 153-167 [10.1007/s00775-005-0060-y].
De Sanctis, G; Fasciglione, G; Marini, S; Sinibaldi, F; Santucci, R; Monzani, E; Dallacosta, C; Casella, L; Coletta, M
Articolo su rivista
File in questo prodotto:
File Dimensione Formato  
JBIC2006hemcas.pdf

accesso aperto

Dimensione 537.78 kB
Formato Adobe PDF
537.78 kB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/39709
Citazioni
  • ???jsp.display-item.citation.pmc??? 1
  • Scopus 5
  • ???jsp.display-item.citation.isi??? 5
social impact