Acetonitrile-induced conformational transitions in poly-L-lysine.
The effect of acetonitrile on the random coil, alpha-helix and beta-sheet conformations induced in poly-L-lysine is studied. It is found that acetonitrile at higher concentrations transforms the backbone of polylysine from a random coil to a helical conformation. Addition of acetonitrile to polylysine (pH 11.5) in the alpha-helix conformation, induces conformational changes in two stages. At concentrations below 60% v/v, acetonitrile stabilizes the helical conformation and at higher concentrations (> 70% v/v), it destabilizes the helix. beta-sheet-->alpha-helix-->random coil conformational transitions are found to occur when polylysine in the heat-induced conformation is titrated with acetonitrile. The possible mechanism(s) of action of acetonitrile in inducing these structural transitions is discussed.
Arunkumar
A I
AI
Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan.
Kumar
T K
TK
Sivaraman
T
T
Yu
C
C
D000097:Acetonitriles / Q000737:chemistry / Q000494:pharmacology*; D002942:Circular Dichroism; D006863:Hydrogen-Ion Concentration; D011107:Polylysine / Q000737:chemistry* / Q000187:drug effects; D011487:Protein Conformation / Q000187:drug effects
D000097:Acetonitriles; D011107:Polylysine; C032159:acetonitrile