Chain length-function correlation of amphiphilic peptides. Synthesis and surface properties of a tetratetracontapeptide segment of apolipoprotein A-I.
The segment corresponding to residues 121 to 164 of human plasma apolipoprotein A-I (apo-A-I) has been synthesized by the Merrifield solid phase method. The peptide binds to unilamellar phospholipid vesicles and to phospholipid-cholesterol mixed vesicles. The surface affinity of the peptide measured in this way indicated that the mechanism of binding is the same as that of apo A-I (144-165) and apo A-I itself. The peptide appears to be a globular monomer in a aqueous solution, with 17% alpha helix content. The peptide bound to vesicles activates lecithin:cholesterol acyltransferase: compared to apo A-I, the peptide is about 30% as efficient in the activation of cholesterol esterification and of phospholipid hydrolysis when the surface is saturated by the activator. For a variety of amphiphilic peptides and for apo A-I, the lecithin: cholesterol acyltransferase-activating ability correlates well with their alpha helix contents in 50% trifluoroethanol.
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D016632:Apolipoprotein A-I; D001053:Apolipoproteins / Q000097:blood*; D002942:Circular Dichroism; D004789:Enzyme Activation; D006801:Humans; D007700:Kinetics; D008081:Liposomes; D010455:Peptides / Q000138:chemical synthesis* / Q000494:pharmacology; D007862:Phosphatidylcholine-Sterol O-Acyltransferase / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D013499:Surface Properties
D000596:Amino Acids; D016632:Apolipoprotein A-I; D001053:Apolipoproteins; D008081:Liposomes; D010455:Peptides; D007862:Phosphatidylcholine-Sterol O-Acyltransferase