The structural and redox properties of a heme-containing fragment (1-56 residues) of cytochrome c have been investigated by spectroscopic (circular dichroism, electronic absorption, and EPR) and voltammetric techniques. The results indicate that the N-fragment lacks ordered secondary structure and has two histidines axially bound to the heme-iron (the native His18 and a misligated His26 or His33). Despite the absence of ordered secondary structure, the peptide chain shields the heme group from solvent, as shown by (i) the pK(a) of protonation of the nonnative histidine ligand (5.18 +/- 0.05), lower than that of the bis-histidine guanidine-unfolded cytochrome c (5.58 +/- 0.05), and (ii) the redox potential, E-o = 0 +/- 5 mV versus NHE, close to that of bis-histidine cytochrome c mutants but less negative than that of bis-histidine complexes of microperoxidase with short peptides. The electroactive N-fragment may be taken as a "minichrome c" model, with interesting potential for application to biosensor technology; further, the system provides useful information far a deeper understanding of cytochrome c folding and structural/functional organization. (C) 2000 Academic Press.

Santucci R., F.L. (2000). The heme-containing N-fragment (residues 1-56) of cytochrome c is a bis-histidine functional system. ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS, 379(2), 331-336 [10.1006/abbi.2000.1885].

The heme-containing N-fragment (residues 1-56) of cytochrome c is a bis-histidine functional system

SANTUCCI, ROBERTO;FIORUCCI, LAURA;SINIBALDI, FEDERICA;POLIZIO, FRANCESCA;DESIDERI, ALESSANDRO;
2000

Abstract

The structural and redox properties of a heme-containing fragment (1-56 residues) of cytochrome c have been investigated by spectroscopic (circular dichroism, electronic absorption, and EPR) and voltammetric techniques. The results indicate that the N-fragment lacks ordered secondary structure and has two histidines axially bound to the heme-iron (the native His18 and a misligated His26 or His33). Despite the absence of ordered secondary structure, the peptide chain shields the heme group from solvent, as shown by (i) the pK(a) of protonation of the nonnative histidine ligand (5.18 +/- 0.05), lower than that of the bis-histidine guanidine-unfolded cytochrome c (5.58 +/- 0.05), and (ii) the redox potential, E-o = 0 +/- 5 mV versus NHE, close to that of bis-histidine cytochrome c mutants but less negative than that of bis-histidine complexes of microperoxidase with short peptides. The electroactive N-fragment may be taken as a "minichrome c" model, with interesting potential for application to biosensor technology; further, the system provides useful information far a deeper understanding of cytochrome c folding and structural/functional organization. (C) 2000 Academic Press.
Pubblicato
Rilevanza internazionale
Articolo
Sì, ma tipo non specificato
Settore BIO/10
English
Con Impact Factor ISI
Circular dichroism; Cytochrome c; Electrochemistry; N-fragment
Santucci R., F.L. (2000). The heme-containing N-fragment (residues 1-56) of cytochrome c is a bis-histidine functional system. ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS, 379(2), 331-336 [10.1006/abbi.2000.1885].
Santucci, R; Fiorucci, L; Sinibaldi, F; Polizio, F; Desideri, A; Ascoli, F
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2108/49989
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