Evidence for the molten globule state of human apo-ceruloplasmin.
The conformational features of copper-free ceruloplasmin (CP), as compared to the holo-protein, were evaluated utilizing far- and near-UV circular dichroism and fluorescence spectroscopy. The results obtained indicate that apo-CP maintains the secondary structure of the holo-protein, while the tertiary interactions are much weaker. In addition, the removal of copper from the holo-protein leads to the exposure of hydrophobic patches to solvent, as shown by the fact that apo-CP, at variance from the holo-protein, binds the hydrophobic probe ANS. It is proposed that the CP molecule, upon copper removal, acquires the conformational features typical of a molten globule, which might be the conformational state of CP during its biosynthesis before metal incorporation.
De Filippis
V
V
CRIBI Biotechnology Centre, University of Padua, Italy.
Vassiliev
V B
VB
Beltramini
M
M
Fontana
A
A
Salvato
B
B
Gaitskhoki
V S
VS
D000817:Anilino Naphthalenesulfonates / Q000378:metabolism; D001059:Apoproteins / Q000737:chemistry*; D002570:Ceruloplasmin / Q000737:chemistry*; D002942:Circular Dichroism; D003300:Copper / Q000378:metabolism / Q000494:pharmacology*; D006527:Hepatolenticular Degeneration / Q000503:physiopathology; D006801:Humans; D008667:Metalloproteins / Q000737:chemistry; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence
D000817:Anilino Naphthalenesulfonates; D001059:Apoproteins; D008667:Metalloproteins; C006612:apoceruloplasmin; C027132:1-anilino-8-naphthalenesulfonate; D003300:Copper; D002570:Ceruloplasmin