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Effect of phospholipid bilayers on solution conformation of branched polymeric polypeptides and peptide–polymer conjugates
Author(s) -
Nagy Ildikó B.,
Majer Zsuzsa,
Hudecz Ferenc
Publication year - 2001
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/1097-0282(200102)58:2<152::aid-bip40>3.0.co;2-v
Subject(s) - chemistry , phospholipid , conjugate , liposome , oligopeptide , peptide , aqueous solution , polylysine , stereochemistry , crystallography , membrane , organic chemistry , biochemistry , mathematical analysis , mathematics
This report provides a detailed analysis on the influence of phosholipid bilayers on the conformation of poly[Lys( X i – DL ‐Ala m )] (XAK, where X = Ser, Orn, Glu, or AcGlu) type branched polypeptides and their peptide conjugates. CD spectra of polycationic (SAK, OAK), amphoteric (EAK), or polyanionic (Ac‐EAK) polylysine derivatives were recorded in 0.25 M acetate buffer at pH 7.4 as well as in the presence of DPPC or DPPC/PG (95/5, 80/20 mol/mol) liposomes. Based on these data, two groups of polypeptides are described. Group one contains polypeptides with significantly ordered conformation even in buffer solution (SAK, AcEAK), which is essentially not altered by phospholipids. Group two, branched polypeptides (OAK, EAK), with only partially ordered conformation in aqueous solution in the presence of phospholipid bilayers with high PG content, could adopt more (EAK) or less (OAK) ordered α‐helical structure depending on their charge properties. In addition, we report on the synthesis of two new sets of oligopeptide‐branched polypeptide conjugates. Studies with selected conjugates suggest that these compounds are highly ordered in buffer solution almost regardless from the helix‐forming ability of the carrier (AK, SAK, EAK) and from the hydrophilic/hydrophobic character of peptides attached (AVKDEL vs FWRGDLVFDFQV). Addition of phospholipid bilayers with different composition essentially had no modifying effect on conformation of conjugates. From this we can conclude that the covalently coupled oligopeptides has a predominant effect of the conformational properties of conjugates. © 2001 John Wiley & Sons, Inc. Biopoly 58: 152–164, 2001