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- Jackson, Graham E, et al.
(författare)
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Solution conformations of an insect neuropeptide : crustacean cardioactive peptide (CCAP)
- 2009
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Ingår i: Peptides. - : Elsevier BV. - 0196-9781 .- 1873-5169. ; 30:3, s. 557-564
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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- Mugumbate, Grace, et al.
(författare)
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Anopheles gambiae, Anoga-HrTH hormone, free and bound structure : A nuclear magnetic resonance experiment
- 2013
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Ingår i: Peptides. - : Elsevier BV. - 0196-9781 .- 1873-5169. ; 41, s. 94-100
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Tidskriftsartikel (refereegranskat)abstract
- The spread of malaria by the female mosquito, Anopheles gambiae, is dependent, amongst other things, on its ability to fly. This in turn, is dependent on the adipokinetic hormone, Anoga-HrTH (pGlu-Leu-Thr-Phe-Thr-Pro-Ala-Trp-NH2). No crystal structure of this important neuropeptide is available and hence NMR restrained molecular dynamics was used to investigate its conformational space in aqueous solution and when bound to a membrane surface. The results showed that Anoga-HrTH has an almost cyclic conformation that is stabilized by a hydrogen bond between the C-terminus and Thr3. Upon docking of the agonist to its receptor, this H-bond is broken and the molecule adopts a more extended structure. Preliminary AKHR docking calculations give the free energy of binding to be -47.30 kJ/mol. There is a close correspondence between the structure of the docked ligand and literature structure-activity studies. Information about the 3D structure and binding mode of Anoga-HrTH to its receptor is vital for the design of suitable mimetics which can act as insecticides.
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- Munyuki, Gadzikano, et al.
(författare)
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beta-Sheet Structures and Dimer Models of the Two Major Tyrocidines, Antimicrobial Peptides from Bacillus aneurinolyticus
- 2013
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 52:44, s. 7798-7806
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Tidskriftsartikel (refereegranskat)abstract
- The structures of two major tyrocidines, antibiotic peptides from Bacillus aneurinolyticus, in an aqueous environment were studied using nuclear magnetic resonance spectroscopy, restrained molecular dynamics (MD), circular dichroism, and mass spectrometry. TrcA and TrcC formed beta-structures in an aqueous environment. Hydrophobic and hydrophilic residues were not totally separated into nonpolar and polar faces of the peptides, indicating that tyrocidines have low amphipathicity. In all the beta-structures, residues Trp(4)/Phe(4) and Orn(9) were on the same face. The ability of the peptides to form dimers in aqueous environment was studied by replica exchange MD simulations. Both peptides readily dimerize, and predominant complex structures were characterized through cluster analysis. The peptides formed dimers by either associating sideways or stacking on top of each other. Dimers formed through sideways association were mainly stabilized by hydrogen bonding, while the other dimers were stabilized by hydrophobic interactions. The ability of tyrocidine peptides to form different types of dimers with different orientations suggests that they can form larger aggregates, as well.
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