Chicken Liver Bile Acid-Binding Protein is in a Compact Partly Folded State at Acidic pH. Its Relevance to the Interaction with Lipid Membranes.

VERÓNICA NOLAN,; MASSIMILIANO PERDUCA,; MONACO, HUGO L.; GUILLERMO GABRIEL MONTICH

American Chemical Society

Año: 2005 vol. 44 p. 8486 - 8486

BSTRACT: Chicken liver bile acid-binding protein (formerly known as chicken liver basic fatty acidbinding protein) binds to anionic lipid membranes acquiring a partly folded state [Nolan, V., Perduca, M., Monaco, H., Maggio, B., and Montich, G. (2003) Biochim. Biophys. Acta 1611, 98-106]. To understand the mechanisms of its interactions with membranes, we have investigated the presence of partly folded states in solution. Using fluorescence spectroscopy of the single Trp residue, circular dichroism in the far- and near-UV, Fourier transform infrared spectroscopy, and size-exclusion chromatography, we found that L-BABP was partly unfolded at pH 2.5 and low ionic strength, retaining some of its secondary structure. Addition of 0.1 M NaCl at pH 2.5 or decreasing the pH to 1.5 produced a more compact partly folded state, with a partial increase of secondary structure and none of tertiary structure. Fluorescence emission spectra of this state indicate that the Trp residue is within