Three-dimensional structure of gurmarin,a sweet taste-suppressing polypeptide |
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Authors: | Katsuaki Arai Rieko Ishima Soichi Morikawa Akiko Miyasaka Toshiaki Imoto Shoko Yoshimura Saburo Aimoto Kazuyuki Akasaka |
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Institution: | (1) Department of Chemistry, Faculty of Science, Kyoto University, 606 Kyoto, Japan;(2) Protein Engineering Research Institute, 565 Suita, Japan;(3) Faculty of Medicine, Tottori University, 683 Yonago, Japan;(4) Protein Research Institute, Osaka University, 565 Suita, Japan;(5) Department of Chemistry, Faculty of Science, Kobe University, 657 Kobe, Japan |
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Abstract: | Summary The solution structure of gurmarin was studied by two-dimensional proton NMR spectroscopy at 600 MHz. Gurmarin, a 35-amino acid residue polypeptide recently discovered in an Indian-originated tree Gymnema sylvestre, selectively suppresses the neural responses of rat to sweet taste stimuli. Sequence-specific protons. The three-dimensional solution structure was determined by simulated-annealing calculations on the basis of 135 interproton distance constraints derived from NOEs, six distance constraints for three hydrogen bonds and 16 dihedral angle constraints derived from coupling constants. A total of 10 structures folded into a well-defined structure with a triple-stranded antiparallel -sheet. The average rmsd values between any two structures were 1.65±0.39 Å for the backbone atoms (N, C , C) and 2.95±0.27 Å for all heavy atoms. The positions of the three disulfide bridges, which could not be deterermined chemically, were estimated to be Cys3–Cys18, Cys10–Cys23 and Cys17–Cys33 on the basis of the NMR distance constraints. This disulfide bridge pattern in gurmarin turned out to be analogous to that in -conotoxin and Momordica charantia trypsin inhibitor-II, and the topology of folding was the same as that in -conotoxin.Abbreviations DQF-COSY
double-quantum-filtered correlated spectroscopy
- HOHAHA
homonuclear Hartmann-Hahn spectroscopy
- NOESY
nuclear Overhauser enhancement spectroscopy
- ppm
parts per million; rmsd, root-mean-square deviation
- TSP
3-(trimethylsilyl)-2,2,3,3-tetradeutero-propionate |
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Keywords: | Three-dimensional structure Two-dimensional NMR Simulated annealing Sweet taste-suppressing polypeptide Gymnema sylvestre |
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