Polypeptide helices in hybrid peptide sequences.
A new class of polypeptide helices in hybrid sequences containing alpha-, beta-, and gamma-residues is described. The molecular conformations in crystals determined for the synthetic peptides Boc-Leu-Phe-Val-Aib-betaPhe-Leu-Phe-Val-OMe 1 (betaPhe: (S)-beta3-homophenylalanine) and Boc-Aib-Gpn-Aib-Gpn-OMe 2(Gpn: 1-(aminomethyl)cyclohexaneacetic acid) reveal expanded helical turns in the hybrid sequences (alpha alphabeta)n and (alphagamma)n. In 1, a repetitive helical structure composed of C14 hydrogen-bonded units is observed, whereas 2 provides an example of a repetitive C12 hydrogen-bonded structure. Using experimentally determined backbone torsion angles for the hydrogen-bonded units formed by hybrid sequences, we have generated energetically favorable hybrid helices. Conformational parameters are provided for C11, C12, C13, C14, and C15 helices in hybrid sequences.
Ananda
Kuppanna
K
Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India.
Vasudev
Prema G
PG
Sengupta
Anindita
A
Raja
K Muruga Poopathi
KM
Shamala
Narayanaswamy
N
Balaram
Padmanabhan
P
D003198:Computer Simulation; D018257:Helix-Loop-Helix Motifs; D006860:Hydrogen Bonding; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D017433:Protein Structure, Secondary / Q000235:genetics
D010455:Peptides