Non-specific helix-induction in charged homopolypeptides by alcohols.
The specificity/non-specificity of helix-induction in charged homopolymers such as polylysine and polyglutamic acid, at neutral pH, by various alcohols namely 2,2,2-trifluoroethanol (TFE), methanol, ethanol and 1-propanol is studied. It is found that all the alcohols used, non-specifically induced helical conformation at high concentrations. In addition, the effect(s) of TFE on an all beta-sheet protein, such cardiotoxin analogue I (CTX I) from the Taiwan Cobra (Naja naja atra) is also studied. Evaluation of the helix propensity in the amino-acid sequence of CTX I using helix-coil algorithm, AGADIR, shows a total of 1.15% helical content in the protein. In CTX I, helical conformation is found to be induced at high concentrations of TFE (> or = 70% v/v). Interestingly, upon denaturation and reduction of disulfide bridges in CTX I, helix is found to be induced even at low concentrations of TFE (> or = 20% v/v). The results of this study hints at the possible influence of native tertiary structural interactions and disulfide bridges in 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
D000433:1-Propanol; D000438:Alcohols; D002942:Circular Dichroism; D000431:Ethanol; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D000432:Methanol; D011099:Polyglutamic Acid / Q000737:chemistry*; D011107:Polylysine / Q000737:chemistry*; D017433:Protein Structure, Secondary; D014270:Trifluoroethanol
D000438:Alcohols; D011107:Polylysine; D011099:Polyglutamic Acid; D000431:Ethanol; D014270:Trifluoroethanol; D000433:1-Propanol; D000432:Methanol