Download MendeleyThe Bowman-Birk Inhibitor Reactive Site Loop Sequence Represents an Independent Structural Beta-Hairpin Motif
Brauer, A.B.E., Kelly, G., Mcbride, J.D., Cooke, R.M., Matthews, S.J., Leatherbarrow, R.J.(2001) J Mol Biol 306: 799
- PubMed: 11243789
- DOI: https://doi.org/10.1006/jmbi.2000.4410
- Primary Citation of Related Structures:
1HD9 - PubMed Abstract:
We have determined the NMR structure in aqueous solution of a disulphide-cyclised 11-residue peptide that forms a stable beta-hairpin, incorporating a type VIb beta-turn. The structure is found to be extremely well ordered for a short peptide, with the 30 lowest energy simulated annealing structures having an average pairwise r.m.s. deviation of only 0.36 A over the backbone. All but three side-chains adopt distinct conformations, allowing a detailed analysis of their involvement in cross-strand interactions. The peptide sequence analysed originates from a previously reported study, which identified potent inhibitors of human leukocyte elastase from screening a combinatorial peptide library based on the short protein beta-sheet segment that forms the reactive site loop of Bowman-Birk inhibitors. A detailed comparison of the peptide's solution structure with the corresponding region in the whole protein structure reveals a very good correspondence not only for the backbone (r.m.s. deviation approximately 0.7 A) but also for the side-chains. This isolated beta-hairpin retains the biologically active "canonical conformation" typical of small serine proteinase inhibitor proteins, which explains why it retains inhibitory activity. Since the structural integrity is sequence-inherent and does not depend upon the presence of the remaining protein, this beta-hairpin represents an independent structural motif and so provides a useful model of this type of protein architecture and its relation to biological function. The relationship between the conformation of this beta-hairpin and its biological activity is discussed.
Organizational Affiliation:
Department of Chemistry, Imperial College of Science Technology and Medicine, South Kensington, London, UK.
