Fusion of negatively charged liposomes induced by peptides of the N-terminal fragment of HIV-1 transmembrane protein

The fusion of the negatively charged liposomes (phosphatidylcholine-phosphatidylethanolamine olipin = 2:3:5) induced by synthetic peptides corresponding to the N-terminal region of the human immunodeficiency virus transmembrane glycoprotein (gp41) was studied. Peptides which are identical to the N-terminal sequence of gp41 (residues 517-538) are of the highest activity, and their activity increases at pH 6.0. A peptide with C-terminal lysine has the highest sensitivity to pH. The peptides conjugated with serum albumin or synthetic polymers are completely inactive. The peptide hydrophobicity was shown to decrease at pH 6.0 using the ANSA fluorescent probe. Under these conditions, the peptide-induced leakage of liposome is lower. The effect of the peptide structure on liposome fusion is discussed.