Peptide destabilization by two adjacent D-amino acids in single-stranded amphipathic alpha-helices.
We recently described the local destabilizing effect of systematic double D-amino acid replacements for characterization of amphipathic helices in peptides. The objective of this study was to determine the destabilizing effect of two adjacent D-amino acids incorporated into the center of a single-stranded amphipathic alpha-helix by hydrogen exchange and guanidine hydrochloride denaturation studies in trifluoroethanol (TFE)/water. Data from guanidine hydrochloride titration experiments in the presence of 30% TFE suggest that double D-amino acid replacements at the center of the helix destabilize the secondary structure by 4.5 kJ/mol. While the exchange rate for one backbone proton was found to vary by a factor of 10 at the replacement position, the remaining backbone protons are not markedly influenced by double D-amino acid replacement. These results confirm the hypothesis that the energy of -4.5 kJ/mol per residue is a major contribution to the stability of helical peptides in water and in solvent mixtures of TFE/water.
Rothemund
S
S
Institute of Molecular Pharmacology, Berlin, Germany.
Krause
E
E
Beyermann
M
M
Dathe
M
M
Bienert
M
M
Hodges
R S
RS
Sykes
B D
BD
Sönnichsen
F D
FD
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry*; D002942:Circular Dichroism; D019791:Guanidine; D006146:Guanidines / Q000494:pharmacology; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry* / Q000187:drug effects; D011489:Protein Denaturation; D017433:Protein Structure, Secondary; D013237:Stereoisomerism; D017186:Titrimetry
D000596:Amino Acids; D006146:Guanidines; D010455:Peptides; D019791:Guanidine