Specificity of helix-induction by 2,2,2-trifluoroethanol in polypeptides.
The specificity of helix-induction in polypeptides by 2,2,2-trifluoro ethanol (TFE) is studied using an all beta-sheet protein such as cardiotoxin analogue I (CTX I) from the Taiwan Cobra (Naja naja atra) and a homopolymer such as poly-L-lysine. It is found that alcohols including TFE can 'non-specifically' induce helix at high concentrations both in CTX I and polylysine at neutral pH. However, among the alcohols used, only TFE could transform the heat-induced beta-sheet conformation of polylysine at pH 11.5 into an alpha-helix. The beta-sheet to alpha-helix conversion in polylysine (in the beta-sheet conformation) occurs even at very low concentrations of TFE (< 5% v/v). In addition, experiments on the effect(s) of TFE on the denatured and reduced CTX I (rCTX I) indicate the helix-induction in rCTX I takes place at low TFE concentrations (< 20% v/v). The results of this study hint at the possible influence of disulfide bridges on the induction of helix by TFE.
Arunkumar
A I
AI
Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan.
Kumar
T K
TK
Yu
C
C
D000595:Amino Acid Sequence; D002942:Circular Dichroism; D004179:Cobra Cardiotoxin Proteins / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry* / Q000187:drug effects*; D011107:Polylysine / Q000737:chemistry / Q000187:drug effects; D017510:Protein Folding; D017433:Protein Structure, Secondary / Q000187:drug effects*; D014270:Trifluoroethanol / Q000494:pharmacology*
D004179:Cobra Cardiotoxin Proteins; D010455:Peptides; D011107:Polylysine; D014270:Trifluoroethanol