Influence of alpha-helices on the emulsifying properties of proteins

A peptide derived from apomyoglobin by cyanogen bromide cleavage was found to be an active emulsifier. This molecule, peptide 1-55, has two potential amphipathic alpha -helices and a hydrophilic C-terminal domain. The importa nce of each of these domains to the emulsifying properties of this molecule was investigated by testing the products of gene constructs based on the s equence of peptide 1-55, but lacking one of the three domains. The emulsify ing activity of the peptides lacking either of the alpha -helices was corre lated with the hydrophobic moments of their respective helices. The hydroph obic moment is a measure of the amphipathicity of alpha -helices; a hydroph obic moment analysis of other emulsifying peptides supports the hypothesis that a high hydrophobic moment contributes to good emulsifying properties i n a molecule which contains alpha -helices.