NMR studies of the solution conformation and dynamics of the tyrocidine peptide antibiotics
The tyrocidine B and tyrocidine C /sup 1/H NMR spectra in DMSO-d/sub 6/ were assigned by using 2D /sup 1/H-/sup 1/H correlation spectroscopy and 1D double resonance experiments. Based on the proton chemical shifts, /sup 3/J/sub NH-N..cap alpha../ coupling constants, the chemical shift temperature dependence, and 1D and 2D /sup 1/H-/sup 1/H NOE values, a backbone conformation consisting of an anti-parallel ..beta..-pleated sheet, a type I ..beta..-turn and a type II' ..beta..-turn was suggested for both tyrocidines B and C. Seven out of ten side chains were determined to exist predominantly in one classical Chi/sub 1/ rotamer; while the residues Val/sup 1/ and Leu/sup 3/ had two Chi/sub 1/ rotamers which were significantly populated. Chi/sub 2/ angles were determined for residues Phe/sup 4/, Trp/sup 6/, DPhe/sup 7/ (D Trp/sup 7/) and Asn/sup 8/. The natural abundance /sup 13/C spectra of tyrocidine B and tyrocidine C were assigned by using /sup 1/H-/sup 13/C correlation spectroscopy. A study of the effect of soluble paramagnetic nitroxide compounds on tyrocidine A proton T/sub 1/ values were performed which confirmed the proposed tyrocidine A conformation. It also proved that these nitroxide compounds are very useful in studying proton solvent exposure, and therefore in delineating hydrogen bonding. A proton NMR study of the opioid peptide dynorphin-(1-13) in aqueous solution was reported which was consistent with a non-ordered molecule in the solution.
- Research Organization:
- Wisconsin Univ., Madison (USA)
- OSTI ID:
- 6104391
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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