MOLECULAR-DYNAMICS SIMULATION OF THE STABILITY OF A 22-RESIDUE ALPHA-HELIX IN WATER AND 30-PERCENT TRIFLUOROETHANOL

A molecular dynamics (MD) simulation was performed on the alpha-helix H8-HC5, the C-terminal part of myoglobin (residue 132-153), under peri odic boundary conditions in two different solutions, water and water w ith 30% (v/v) 2,2,2-trifluoroethanol (TFE), at 300 K to investigate th e stability of the helix. In both simulations, the initial configurati on was a canonical right-handed alpha-helix. In the course of the MD t rajectory in water (200 ps), the helix clearly destabilized and began to unfold after 100 ps. In the TFE solution, two stable parts of helic al regions were observed after 70 ps of a 200-ps MD simulation, suppor ting the notion that TFE acts as a structure-forming solvent. (C) 1993 John Wiley & Sons, Inc.