Interaction of substance P with phospholipid bilayers: A neutron diffraction study.
Neutron diffraction has been used to study the membrane-bound structure of substance P (SP), a member of the tachykinin family of neuropeptides. The depth of penetration of its C-terminus in zwitterionic and anionic phospholipid bilayers was probed by specific deuteration of leucine 10, the penultimate amino acid residue. The results show that the interaction of SP with bilayers, composed of either dioleoylphosphatidylcholine (DOPC), or a 50:50 mixture of DOPC and the anionic phospholipid dioleoylphosphatidylglycerol (DOPG), takes place at two locations. One requires insertion of the peptide into the hydrophobic region of the bilayer, the other is much more peripheral. The penetration of the peptide into the hydrophobic region of the bilayer is reflected in a marked difference in the water distribution profiles. SP is seen to insert into DOPC bilayers, but a larger proportion of the peptide is found at the surface when compared to the anionic bilayers. The positions of the two label populations show only minor differences between the two types of bilayer.
Department of Preclinical Veterinary Sciences, Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Summerhall, Edinburgh EH9 1QH, Scotland, United Kingdom. j.bradshaw@ed.ac.uk
J P
JP
Bradshaw
S M
SM
Davies
T
T
Hauss
D017666:Deuterium Oxide; D008051:Lipid Bilayers / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009502:Neutrons; D010713:Phosphatidylcholines / Q000737:chemistry*; D010715:Phosphatidylglycerols / Q000737:chemistry*; D011487:Protein Conformation; D012542:Scattering, Radiation; D013329:Structure-Activity Relationship; D013373:Substance P / Q000737:chemistry*
D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D010715:Phosphatidylglycerols; D013373:Substance P; C051388:1,2-dioleoyl-sn-glycero-3-phosphoglycerol; C017251:1,2-oleoylphosphatidylcholine; D017666:Deuterium Oxide