Solution Structures of α- and β-Amanitin via Distance Geometry Calculations and a Relaxation-Matrix Analysis of Nuclear Overhauser Effect Spectra
✍ Scribed by S. Acheson; M.H. Lambert; S.C. Brown; P.W. Jeffs
- Publisher
- Elsevier Science
- Year
- 1993
- Tongue
- English
- Weight
- 617 KB
- Volume
- 101
- Category
- Article
- ISSN
- 1064-1866
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✦ Synopsis
The solution structures of (\alpha) - and (\beta)-amanitin in dimethyl sulfoxide/chloroform (85/15) at (286 \mathrm{~K}) have been examined through analysis of two-dimensional double-quantum-filtered correlated spectra and nuclear-Overhauser-effect spectra (NOESY). The NOESY data were analyzed by both a two-spin approximation and a relaxation-matrix analysis. Analysis of NOESY data acquired with a long mixing time ( (\tau_{\mathrm{m}}>T_{1}) ) provides experimental verification that the two-spin approximation underestimates interproton distances greater than approximately (3.0 \AA). The interproton distances obtained from relaxation-matrix analyses were used in combination with distance-geometry-based calculations to compute a set of 10 solution structures for each compound. The sets of solution structures compare favorably with reported crystal structures for these compounds. A simplified relaxation-matrix-analysis procedure is presented which can estimate interproton distances from a set of references distances and a single NOESY volume matrix. This simplified analysis was used together with a cross-validation procedure to investigate the accuracy of computed distances. In the present case, distances obtained with the relaxation analysis are slightly more accurate than distances obtained with a simplified two-spin analysis. c) 1993 Academic Press, Inc.