Specific formation of trypsin resistant micelle structure on a hydrophobic peptide observed with Triton X−100 but not with ocytlglucoside

Interaction manners of the coat peptide of Pf3 phage, Pf3 peptide, with lipid bilayer have been extensively studied. We designed a derivative of Pf3 peptide, referred to as DDRK peptide, and this peptide was subjected to trypsin digestion to understand its physicochemical properties. In the presence of Triton X−100 used for solubilization of DDRK peptide, trypsin digestion of DDRK peptide caused specific cleavage at its N-terminal Lysine residue. N-terminal region of the DDRK peptide is relatively hydrophilic, but its remaining region is hydrophobic. Thus, hydrophobic region of DDRK peptide is expected to be coated by Triton micelle, and formation of micelle structure of Triton seemed to cause selective cleavage of the DDRK peptide at its hydrophilic N-terminal Lys residue by trypsin. However, such protective effect on the DDRK peptide against trypsin digestion was not observed with octylglucoside. The observed results are important for understanding the interaction manners of detergents with hydrophobic peptides.