title: Vibrational analysis of peptides, polypeptides and proteins. XXVII. Structure of gramicidin S from normal mode analyses of low-energy conformations.
abstract: Normal mode calculations have been carried out on three low-energy structures of gramicidin S obtained from conformational energy calculations. When the results on the amide modes are compared with observed bands in the infrared and Raman spectra of crystalline gramicidin S and its N-deuterated derivative, one of the structures is clearly disfavored. Of the other two, one is slightly favored, and it corresponds to the lowest-energy structure obtained from the energy calculations. Spectra from solutions in DMSO and CH3 OH suggest that the molecular conformation is essentially retained in these solvents.
mesh_terms: D003461:Crystallography; D006096:Gramicidin; D009038:Motion; D011487:Protein Conformation; D012996:Solutions; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman; D013816:Thermodynamics
chemical_list: D012996:Solutions; D006096:Gramicidin