title: Determination of the intramolecular tyrosine-tryptophan distance in a 7-peptide related to the C-terminal sequence of cholecystokinin.
abstract: The solution conformation of a 7-peptide with the C-terminal sequence of cholecystokinin was investigated by evaluation of intramolecular resonance energy transfer between tyrosine (donor) in position 1 and tryptophan (acceptor) in position 4. From the relative enhancement of acceptor fluorescence a transfer efficiency of 0.70 +/- 0.04 was determined. The use of this parameter in Förster's equation permitted the calculation of the average intramolecular tyrosine-tryptophan separation, whereby the assumption of random donor-acceptor orientation was made. The resulting average distance of 10.0 +/- 0.3 A suggests some type of a folded conformation and excludes the existence of a fully extended chain in the N-terminal part of the peptide. A comparison with tyrosine-tryptophan distances observed in other biologically active polypeptides is made.
mesh_terms: D000595:Amino Acid Sequence; D002766:Cholecystokinin / Q000031:analogs & derivatives*; D004735:Energy Transfer; D008968:Molecular Conformation; D010455:Peptides / Q000032:analysis*; D014364:Tryptophan / Q000032:analysis*; D014443:Tyrosine / Q000032:analysis*
chemical_list: D010455:Peptides; D014443:Tyrosine; D014364:Tryptophan; D002766:Cholecystokinin