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Solid-state and solution-phase conformations of pseudoproline-containing dipeptides

Journal Article


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Abstract


  • The conformations of 14 threonine-derived pseudoproline-containing dipeptides (including four d-allo-Thr derivatives) have been investigated by NMR. In solution, the major conformer observed for all dipeptides is that in which the amide bond between the pseudoproline and the preceding amino acid is cis. For dipeptides in which the N-terminus is protected, the ratio of cis- to trans-conformers does not depend significantly on the side chain of the N-terminal amino acid, or the stereochemistry of the Thr residue. However, for dipeptides bearing a free N-terminus, there are significant differences in the ratios of cis- to trans-conformers depending on the side chain present. Three dipeptides were crystallized and their X-ray structures determined. In two cases, (benzyloxycarbonyl (Cbz)-Val-Thr(ΨMe,Mepro)-OMe and Cbz-Val-Thr(ΨMe,Mepro)-OH), the dipeptides adopt a trans-conformation in the solid state, in contrast to the structures observed in solution. In the third case, (9-fluorenylmethoxycarbonyl (Fmoc)-Val-d-allo-Thr(ΨMe,Mepro)-OH), a cis-amide geometry is observed. These structural differences are attributed to crystal-packing interactions.

Authors


  •   Clegg, Jack K. (external author)
  •   Cochrane, James (external author)
  •   Sayyadi, Nima (external author)
  •   Skropeta, Danielle
  •   Turner, Peter (external author)
  •   Jolliffe, Katrina A. (external author)

Publication Date


  • 2009

Citation


  • Clegg, J. K., Cochrane, J. R., Sayyadi, N., Skropeta, D., Turner, P. & Jolliffe, K. A. (2009). Solid-state and solution-phase conformations of pseudoproline-containing dipeptides. Australian Journal of Chemistry: an international journal for chemical science, 62 (7), 711-719.

Scopus Eid


  • 2-s2.0-67949107979

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=1292&context=scipapers

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/258

Number Of Pages


  • 8

Start Page


  • 711

End Page


  • 719

Volume


  • 62

Issue


  • 7

Abstract


  • The conformations of 14 threonine-derived pseudoproline-containing dipeptides (including four d-allo-Thr derivatives) have been investigated by NMR. In solution, the major conformer observed for all dipeptides is that in which the amide bond between the pseudoproline and the preceding amino acid is cis. For dipeptides in which the N-terminus is protected, the ratio of cis- to trans-conformers does not depend significantly on the side chain of the N-terminal amino acid, or the stereochemistry of the Thr residue. However, for dipeptides bearing a free N-terminus, there are significant differences in the ratios of cis- to trans-conformers depending on the side chain present. Three dipeptides were crystallized and their X-ray structures determined. In two cases, (benzyloxycarbonyl (Cbz)-Val-Thr(ΨMe,Mepro)-OMe and Cbz-Val-Thr(ΨMe,Mepro)-OH), the dipeptides adopt a trans-conformation in the solid state, in contrast to the structures observed in solution. In the third case, (9-fluorenylmethoxycarbonyl (Fmoc)-Val-d-allo-Thr(ΨMe,Mepro)-OH), a cis-amide geometry is observed. These structural differences are attributed to crystal-packing interactions.

Authors


  •   Clegg, Jack K. (external author)
  •   Cochrane, James (external author)
  •   Sayyadi, Nima (external author)
  •   Skropeta, Danielle
  •   Turner, Peter (external author)
  •   Jolliffe, Katrina A. (external author)

Publication Date


  • 2009

Citation


  • Clegg, J. K., Cochrane, J. R., Sayyadi, N., Skropeta, D., Turner, P. & Jolliffe, K. A. (2009). Solid-state and solution-phase conformations of pseudoproline-containing dipeptides. Australian Journal of Chemistry: an international journal for chemical science, 62 (7), 711-719.

Scopus Eid


  • 2-s2.0-67949107979

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=1292&context=scipapers

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/258

Number Of Pages


  • 8

Start Page


  • 711

End Page


  • 719

Volume


  • 62

Issue


  • 7