Stereodependent and solvent-specific formation of unusual β-structure through side chain-backbone H-bonding in C4(S)-(NH2/OH/NHCHO)-L-prolyl polypeptides.
It is shown that C4(S)-NH2/OH/NHCHO-prolyl polypeptides exhibit PPII conformation in aqueous medium, but in a relatively hydrophobic solvent trifluoroethanol (TFE) transform into an unusual β-structure. The stereospecific directing effect of H-bonding in defining the specific structure is demonstrated by the absence of β-structure in the corresponding C4(S)-guanidinyl/(NH/O)-acetyl derivatives and retention of β-structure in C4(S)-(NHCHO)-prolyl polypeptides in TFE. The distinct conformations are identified by the characteristic CD patterns and supported by Raman spectroscopic data. The solvent dependent conformational effects are interpreted in terms of intraresidue H-bonding that promotes PPII conformation in water, switching over to interchain H-bonding in TFE. The present observations add a new design principle to the growing repertoire of strategies for engineering peptide secondary structural motifs for innovative nanoassemblies and new biomaterials.
Chemical Biology Unit, Chemistry Discipline, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune, 411008.
Nitin D
ND
Bansode
Chemical Biology Unit, Chemistry Discipline, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune, 411008.
B
B
Madhanagopal
Chemical Biology Unit, Chemistry Discipline, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune, 411008.
Mahesh V
MV
Sonar
Chemical Biology Unit, Chemistry Discipline, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune, 411008.
Krishna N
KN
Ganesh
D000595:Amino Acid Sequence; D002942:Circular Dichroism; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary; D013059:Spectrum Analysis, Raman; D013237:Stereoisomerism; D014270:Trifluoroethanol / Q000737:chemistry*
D010455:Peptides; D014270:Trifluoroethanol
PPII conformation; polyproline peptides; trifluoroethanol; β-structure