Cooperative effect of hydrophobic and electrostatic forces on alcohol-induced α-helix formation of α1-acid glycoprotein

α1-Acid glycoprotein (AGP) is a serum glycoprotein that mainly binds basic drugs. Previous reports have shown that AGP converts from a β-sheet to an α-helix upon interaction with biomembranes. In the current studies, we found that alkanols, diols, and halogenols all induce this conformational change. Increased length and bulkiness of the hydrocarbon group and the presence of a halogen atom promoted this conversion, whereas the presence of a hydroxyl group inhibited it. Moreover, the effect was dependent on the hydrophobic and electrostatic properties of the alcohols. These results indicate that, in a membrane environment, hydrophobic and electrostatic factors cooperatively induce the transition of AGP from a β-sheet to an α-helix.