Interaction of basic extension peptide fragments of adrenodoxin precursor with phospholipid vesicles

Two extension peptide fragments PA1-4 and PA17-32, which correspond to the residues 1-14 and 17-32, respectively, of adrenodoxin precursor, were synthesized by the solution method to find a sequence necessary for the import of the precursor into mitochondria. Biological assay showed that PA1-14 inhibited the import of two mitochondrial enzyme precursors, but PA17-32 showed no inhibition, indicating that the N-terminal sequence has important information for import. CD spectra of the peptides demonstrated that PA1-14 formed alpha-helical structure in Tris-HCl buffer (pH 7.4) containing acidic phospholipid liposomes. Furthermore, PA1-14 induced the moderate leakage of carboxyfluorescein from phospholipid vesicles. The relationship between the structure and function of the peptides is discussed.