Crystal and NMR structures of a Trp-cage mini-protein benchmark for computational fold prediction.
To provide high-resolution X-ray crystallographic structures of a peptide with the Trp-cage fold, we prepared a cyclized version of this motif. Cyclized Trp-cage is remarkably stable and afforded two crystal forms suitable for X-ray diffraction. The resulting higher resolution crystal structures validate the prior NMR models and provide explanations for experimental observations that could not be rationalized by NMR structural data, including the structural basis for the increase in fold stability associated with motif cyclization and the manner in which a polar serine side chain is accommodated in the hydrophobic interior. A hexameric oligomer of the cyclic peptide is found in both crystal forms and indicates that under appropriate conditions, this minimized system may also serve as a model for protein-protein interactions.
Department of Chemistry, University of Washington, Seattle, WA 98195, USA. scian@u.washington.edu
Michele
M
Scian
Jasper C
JC
Lin
Isolde
I
Le Trong
George I
GI
Makhatadze
Ronald E
RE
Stenkamp
Niels H
NH
Andersen
D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000737:chemistry*; D017510:Protein Folding; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary
D010455:Peptides