Studies of peptides forming 3(10)- and alpha-helices and beta-bend ribbon structures in organic solution and in model biomembranes by Fourier transform infrared spectroscopy.
In order to examine the potential correlation between infrared absorption spectra and 3(10)- and alpha-helices and beta-bend ribbon structures, the secondary structures of synthetic peptides known to contain pure 3(10)-helices, mixed 3(10)/alpha-helices, and pure beta-bend ribbon structures, based upon X-ray diffraction and NMR studies, have been investigated by using FTIR spectroscopy incorporating resolution-enhancement techniques. Studies of the peptides known to contain a stable 3(10)-helix in CDCl3 show the main amide I band of fully stable 3(10)-helices occurs at 1666-1662 cm-1. Resolution-enhancement methods revealed small contributions at 1681-1678 and 1646-1644 cm-1, while the amide II band occurs at 1533-1531 cm-1. Peptides known to contain both alpha- and 3(10)-helices in their structure exhibit bands characteristic of both types of conformation. Peptides known to fold into the beta-bend ribbon structure show an amide I band maximum at 1648-1645 cm-1 with the amide II band at 1538-1536 cm-1. Incorporation of these peptides into model membrane structures, e.g., DMPC vesicles, in aqueous buffer sometimes produces changes in the peptide secondary structure. Those peptides which possess a 3(10)-helical structure in CDCl3 solution change the secondary structure in DMPC vesicles to predominantly alpha-helical, plus a contribution from short, unstable 3(10)-helix and/or beta-turns. Those peptides which contain a combination of alpha- and 3(10)-helical structures in CDCl3 solution tend to retain some 3(10)-helical structure within the lipid environment, although the overall H-bonding pattern is altered. Those peptides which form a beta-bend ribbon structure appear to be largely unaffected in the membrane environment.(ABSTRACT TRUNCATED AT 250 WORDS)
Kennedy
D F
DF
Department of Protein and Molecular Biology, Royal Free Hospital School of Medicine, University of London, United Kingdom.
Crisma
M
M
Toniolo
C
C
Chapman
D
D
D000595:Amino Acid Sequence; D000621:Aminoisobutyric Acids; D004134:Dimyristoylphosphatidylcholine; D005583:Fourier Analysis; D008081:Liposomes; D009682:Magnetic Resonance Spectroscopy; D008565:Membrane Proteins / Q000737:chemistry; D008954:Models, Biological; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry*; D011487:Protein Conformation; D012996:Solutions; D013055:Spectrophotometry, Infrared / Q000379:methods; D014961:X-Ray Diffraction
D000621:Aminoisobutyric Acids; D008081:Liposomes; D008565:Membrane Proteins; D010455:Peptides; D012996:Solutions; C100049:2-aminoisobutyric acid; D004134:Dimyristoylphosphatidylcholine