1H nuclear magnetic resonance determination of the membrane-bound conformation of senktide, a highly selective neurokinin B agonist.
Senktide is a highly specific and potent analog of neurokinin B, the natural ligand of the tachykinin receptor NK-3. The membrane-bound conformation of senktide, interacting with negatively charged membrane vesicles composed of perdeuterated phosphatidylcholine and phosphatidylglycerol (70:30), has been investigated using two-dimensional transferred nuclear Overhauser effect spectroscopy (TRNOESY). The occurrence of an N-methylated phenylalanine in the peptide's sequence induces a cis-trans-isomerisation of the corresponding peptide bond which is slow on the chemical-shift scale. NMR data indicate a much stronger membrane affinity of the trans isomer, allowing the determination of a highly resolved membrane-bound conformation using distance geometry and energy minimization. The membrane-bound backbone conformation of several residues is found to be close to a left-handed helix, certainly due to the presence of nonnatural residues (succinylated N-terminal, N-methyl-phenylalanine) as well as a glycine. The results are discussed in the context of a possible biological relevance of the membrane-bound conformation, in terms of the affinity and specificity of this neuropeptide.
Bersch
B
B
Laboratoire de Chimie Organique des Substances Naturelles, associé au CNRS, Université Louis Pasteur, Strasbourg, France.
Koehl
P
P
Nakatani
Y
Y
Ourisson
G
G
Milon
A
A
D000595:Amino Acid Sequence; D008081:Liposomes / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008969:Molecular Sequence Data; D015287:Neurokinin B / Q000031:analogs & derivatives / Q000737:chemistry; D010446:Peptide Fragments / Q000737:chemistry*; D011487:Protein Conformation; D012996:Solutions; D013373:Substance P / Q000031:analogs & derivatives* / Q000737:chemistry; D013816:Thermodynamics; D014867:Water
D008081:Liposomes; D010446:Peptide Fragments; D012996:Solutions; D014867:Water; C054724:senktide; D013373:Substance P; D015287:Neurokinin B