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Solution structures and thermodynamics of cis-trans X-Pro conformers of a novel single disulfide conopeptide

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Title Solution structures and thermodynamics of cis-trans X-Pro conformers of a novel single disulfide conopeptide
 
Creator Kancherla, Aswani K
Sarma, Siddhartha P
 
Subject cis peptide bond
Conopeptide
Conotoxin
Disulphide bond
Solution NMR
 
Description 710-728
The conopeptide Mo1853 (MW = 1853 Da) consists of 17 residues and a single disulfide bond. Structural studies using
homonuclear solution NMR methods (2D 1H,1H DQF-COSY, TOCSY, NOESY and ROESY spectra) revealed that Mo1853
exists as two equally populated cis and trans X–Pro peptide bond conformers which are in slow exchange regime, compared
to the chemical shift time scale. Temperature dependence of chemical shifts was measured and using coalescence
temperature of two amide protons, the rate of exchange and the free energy of activation for the conformational exchange
were determined to be 59 Hz and ≈ 67.2 kJ mol−1, respectively, at 318 K. Additional evidence for this conformational
equilibrium was also observed as exchange correlation peaks in the 2D-NOESY and ROESY spectra. Tertiary structures of
both the cis (PDB ID 8K3N) and trans (PDB ID 8K3M) conformers were determined using distance restraints, backbone
dihedral angle restraints, the disulfide bond restraint and the cis or trans conformation of the X–Pro peptide bond. The trans
conformer of Mo1853 is stabilized by hydrogen bonds while the cis conformer seems to be stabilized predominantly by
hydrophobic interactions. This was further corroborated by the fact that at lower temperatures, the hydrophobic interactions
became weaker reducing the population of the cis conformer with respect to that of the trans conformer. The cis and trans
X–Pro peptide bond conformational exchange could be another means to enhance the structural variability of the
conopeptides and could have significance in the synergistic functional response caused by the cone snail venom peptides.
 
Date 2023-09-20T05:12:34Z
2023-09-20T05:12:34Z
2023-09
 
Type Article
 
Identifier 0975-0959 (Online); 0301-1208 (Print)
http://nopr.niscpr.res.in/handle/123456789/62531
https://doi.org/10.56042/ijbb.v60i9.4061
 
Language en
 
Publisher NIScPR-CSIR,India
 
Source IJBB Vol.60(09) [September 2023]