Intramolecular ditryptophan crosslinks enforce two types of antiparallel beta structures.
BACKGROUND
Two types of biaryl crosslinks can be formed with natural protein sidechains: ditryptophan and dityrosine. Biaryl crosslinks have the same topology as disulfide crosslinks, yet little is known about their effect on local peptide structure.


RESULTS
Three ditryptophan-linked peptide dimers based on the sequence Ac-Leu-Trp-Ala-COX were prepared. The tripeptide dimer with -CONH(2) termini was too insoluble to study, but the tripeptide dimer with -COOMe termini crystallized from methanol/chloroform as an antiparallel beta-sheet. The tripeptide dimer with a -CONMe(2) termini adopted a slipped antiparallel beta structure in methanol/chloroform.


CONCLUSIONS
These results suggest that intermolecular ditryptophan crosslinks that join the middle of peptide chains can confer a preference for antiparallel beta-sheet structure. The effect is most dramatic when both the inside and outside edges of the dimer can form hydrogen bonds as in the crystal structure of dimer 3b.
Matthews
J H
JH
Department of Chemistry, University of California, Irvine, CA 92697-2025, USA.
Dinh
T D
TD
Tivitmahaisoon
P
P
Ziller
J W
JW
Van Vranken
D L
DL
D003460:Crystallization; D018360:Crystallography, X-Ray; D019281:Dimerization; D006860:Hydrogen Bonding; D008958:Models, Molecular; D009842:Oligopeptides / Q000737:chemistry*; D017433:Protein Structure, Secondary; D012995:Solubility; D014364:Tryptophan / Q000378:metabolism*
D009842:Oligopeptides; D014364:Tryptophan