DFT studies on helix formation in N-acetyl-(L-alanyl)n-N′-methylamide for n=1–20

摘要: Abstract We compare the geometries and relative energies of important secondary structural elements, 3.613 helix, 310 helix C5ext structures, for a set blocked peptide models, N-acetyl-( L -alanyl)n-N′-methylamide, n=1–20. use full density-functional theory (DFT) calculations at B3LYP/6-31G* level (for peptides up to 11 residues), self-consistent-charge tight binding (SCC-DFTB) semiempirical AM1 method. The structures are found be not inherently stable in general. Their stability is dependent on length, other motifs aqueous or membrane environments. For short with less than eight residues, relaxes into structure. longer peptides, middle chain, while ends assume conformations, C-terminus additionally βII type turn formed. calculated recently developed SCC-DFTB method very good agreement results from B3LYP calculations. Therefore, we look formation -alanyl)n-N′-methylamide n=11, 14, 17 20. On potential energy surface, find more all sizes. However, effects solution might change this picture favor motif.