Conformational states of annexin VI in solution induced by acidic pH.
Acidic pH-induced folding of annexin (Anx)VI in solution was investigated in order to study the mechanism of formation of ion channels by the protein in membranes. Using 2-(p-toluidino)naphthalene-6-sulfonic acid as a hydrophobic probe, it was demonstrated that AnxVI exerts a large change in hydrophobicity at acidic pH. Moreover, circular dichroism spectra indicated that the native state of AnxVI changes at acidic pH towards a state characterized by a significant loss of alpha-helix content and appearance of new beta-structures. These changes are reversible upon an increase of pH. It is postulated that the structural folding of AnxVI could explain how a soluble protein may undergo transition into a molecule able to penetrate the membrane hydrophobic region. The physiological significance of these observations is discussed.
Golczak
M
M
Department of Cellular Biochemistry, Nencki Institute of Experimental Biology, 3 Pasteur Street, 02-093 Warsaw, Poland.
Kirilenko
A
A
Bandorowicz-Pikula
J
J
Pikula
S
S
D000143:Acids / Q000494:pharmacology*; D000818:Animals; D017317:Annexin A6 / Q000737:chemistry*; D002942:Circular Dichroism; D004735:Energy Transfer; D006863:Hydrogen-Ion Concentration; D007473:Ion Channels; D008099:Liver / Q000737:chemistry; D009282:Naphthalenesulfonates; D011487:Protein Conformation / Q000187:drug effects; D017510:Protein Folding; D017433:Protein Structure, Secondary / Q000187:drug effects; D013050:Spectrometry, Fluorescence; D013552:Swine
D000143:Acids; D017317:Annexin A6; D007473:Ion Channels; D009282:Naphthalenesulfonates; C009497:2-(4-toluidino)-6-naphthalenesulfonic acid