| Abstract
| - We evaluate the effect of the amino acid mutations of glycine, leucine, valine, phenylalanine,serine, and proline for the 10th alanine in the capped peptide, acetly(Ala)17NH2, upon the energies of theα-helices and β-strands using ONIOM DFT/AM1 molecular orbital calculations. The relative stabilities ofthe α-helix (to the β-strand) derive from the differences between the effects upon not only the helix but thestrand as well. Thus, Ala → Pro significantly destabilizes both but destabilizes the α-helix more, while Ala→ Gly stabilizes both but stabilizes the β-strand more. The theoretical results are discussed in the contextof the known experimental reports. We suggest that the solvation of the unfolded state drives the helix/coilequilibrium in solution.
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