Solution conformations of an insect neuropeptide: crustacean cardioactive peptide (CCAP).
The solution structure of crustacean cardioactive peptide (CCAP), a cyclic amidated nonapeptide neurohormone, was studied using molecular dynamics techniques, with constraints derived from NMR studies in water and water/dodecylphosphocholine micellar medium. This peptide, found in various invertebrates, has the primary sequence Pro(1) Phe(2) Cys(3) Asn(4) Ala(5) Phe(6) Thr(7) Gly(8) Cys(9) NH(2), with an intramolecular disulfide bridge between the two cysteine residues. In aqueous solution the peptide was found to have a type(IV) beta-turn between residues 5-8. In a water/decane biphasic medium a type(IV) beta-turn between residues 3 and 6 and two classic gamma-turns between residues 4-6 and 7-9, were found. Analysis of the (1)H and (13)C NMR chemical shifts data showed that the model free S(2) order parameter of the residues varied between 0.65 and 0.9. The molecular dynamic root mean square fluctuations of structural ensembles of the backbone varied between 0.5 and 2.2 with the central residues showing the least fluctuations.
Jackson
Graham E
GE
Chemistry Department, University of Cape Town, Private Bag, 7701 Rondebosch, Cape Town, South Africa. graham.jackson@uct.ac.za
Mabula
Andre N
AN
Stone
Shane R
SR
Gäde
Gerd
G
Kövér
Katalin E
KE
Szilágyi
László
L
van der Spoel
David
D
D000818:Animals; D003198:Computer Simulation; D008958:Models, Molecular; D009479:Neuropeptides / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D012996:Solutions
D009479:Neuropeptides; D012996:Solutions; C058620:crustacean cardioactive peptide