Human serum albumin (HSA) participates in heme scavenging, the bound heme turning out to be a reactivity center and a powerful spectroscopic probe. Here, the reversible unfolding of heme-HSA has been investigated by H-1-NMR relaxometry, circular dichroism, and absorption spectroscopy. In the presence of 6 equiv of myristate ( thus fully saturating all available fatty acid binding sites in serum heme-albumin), 1.0 M guanidinium chloride induces some unfolding of heme-HSA, leading to the formation of a folding intermediate; this species is characterized by increased relaxivity and enhanced dichroism signal in the Soret region, suggesting a more compact heme pocket conformation. Heme binds to the folding intermediate with K-d = (1.2 +/- 0.1) x 10(-6) M. In the absence of myristate, the conformation of the folding intermediate state is destabilized and heme binding is weakened [K-d = (3.4 +/- 0.1) x 10(-5) M]. Further addition of guanidinium chloride ( up to 5 M) brings about the usual denaturation process. In conclusion, myristate protects HSA from unfolding, stabilizing a folding intermediate state in equilibrium with the native and the fully unfolded protein, envisaging a two-step unfolding pathway for heme-HSA in the presence of myristate.

Fanali, G., De Sanctis, G., Gioia, M., Coletta, M., Ascenzi, P., Fasano, M. (2009). Reversible two-step unfolding of heme-human serum albumin: A 1H-NMR relaxometric and circular dichroism study. JBIC, 14(2), 209-217 [10.1007/s00775-008-0439-7].

Reversible two-step unfolding of heme-human serum albumin: A 1H-NMR relaxometric and circular dichroism study

Gioia M.;COLETTA, MASSIMILIANO;
2009-01-01

Abstract

Human serum albumin (HSA) participates in heme scavenging, the bound heme turning out to be a reactivity center and a powerful spectroscopic probe. Here, the reversible unfolding of heme-HSA has been investigated by H-1-NMR relaxometry, circular dichroism, and absorption spectroscopy. In the presence of 6 equiv of myristate ( thus fully saturating all available fatty acid binding sites in serum heme-albumin), 1.0 M guanidinium chloride induces some unfolding of heme-HSA, leading to the formation of a folding intermediate; this species is characterized by increased relaxivity and enhanced dichroism signal in the Soret region, suggesting a more compact heme pocket conformation. Heme binds to the folding intermediate with K-d = (1.2 +/- 0.1) x 10(-6) M. In the absence of myristate, the conformation of the folding intermediate state is destabilized and heme binding is weakened [K-d = (3.4 +/- 0.1) x 10(-5) M]. Further addition of guanidinium chloride ( up to 5 M) brings about the usual denaturation process. In conclusion, myristate protects HSA from unfolding, stabilizing a folding intermediate state in equilibrium with the native and the fully unfolded protein, envisaging a two-step unfolding pathway for heme-HSA in the presence of myristate.
2009
Pubblicato
Rilevanza internazionale
Articolo
Sì, ma tipo non specificato
Settore BIO/10
English
guanidine; heme; human serum albumin; myristic acid; saturated fatty acid; absorption spectroscopy; article; binding site; circular dichroism; denaturation; human; priority journal; protein conformation; protein folding; protein stability; protein structure; proton nuclear magnetic resonance; relaxation time; signal transduction; Binding Sites; Circular Dichroism; Guanidine; Heme; Humans; Magnetic Resonance Spectroscopy; Models, Molecular; Myristic Acid; Protein Conformation; Protein Denaturation; Protein Folding; Protons; Serum Albumin
Fanali, G., De Sanctis, G., Gioia, M., Coletta, M., Ascenzi, P., Fasano, M. (2009). Reversible two-step unfolding of heme-human serum albumin: A 1H-NMR relaxometric and circular dichroism study. JBIC, 14(2), 209-217 [10.1007/s00775-008-0439-7].
Fanali, G; De Sanctis, G; Gioia, M; Coletta, M; Ascenzi, P; Fasano, M
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/41231
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