NMR and molecular dynamics studies of tachykinins: conformation of substance P fragment 4-11

The conformation of the C-terminal octapeptide fragment of Substance P (SP4-11, Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-NH2) has been investigated by 2D-NMR and MD methods. The octapeptide exists in a blend of conformations. The molecule seems to shuttle between conformations with gamma-bends either at Phe5 or Gly6 or Gln3 or Leu7 and between a nearly extended structure.