Alcohol-induced denaturation of beta-lactoglobulin: a close correlation to the alcohol-induced alpha-helix formation of melittin.

Alcohols denature the native structure of proteins and induce alpha-helical structure. The potential of alcohols causing such effects varies substantially depending on the alcohol species. With beta-lactoglobulin as a model protein, we compared the effects of various alcohols and observed the additive contribution of each group constituting the alcohol molecules. Whereas the hydrophobic hydrocarbon group promotes the transition according to their size, hydrophilic hydroxyl group suppresses the transition. Halogen groups promote the transition depending on their type and number. It has been known that alcohols induce the alpha-helical structure on the short peptides such as melittin. There is a close correlation between the potentials of alcohol in denaturing beta-lactoglobulin and those in inducing the helical structure in melittin, indicating that the underlying mechanisms of the two phenomena are the same.