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Nat Struct Biol. 1999 Apr;6(4):331-5.

A cis proline turn linking two beta-hairpin strands in the solution structure of an antibody-bound HIV-1IIIB V3 peptide.

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Department of Structural Biology, The Weizmann Institute of Science, Rehovot, Israel.


The refined solution structure of an 18-residue HIV-1IIIB V3 peptide in complex with the Fv fragment of an anti-gp120 antibody reveals an unexpected type VI beta-turn comprising residues RGPG at the center of a beta-hairpin. The central glycine and proline of this turn are linked by a cis peptide bond. The residues of the turn interact extensively with the antibody Fv. 15N[1H] NOE measurements show that the backbone of the peptide, including the central QRGPGR loop, is well ordered in the complex. The solution structure is significantly different from the X-ray structures of HIV-1MN V3 peptides bound to anti-peptide antibodies. These differences could be due to a two-residue (QR) insertion preceding the GPGR sequence in the HIV-1IIIB strain, and the much longer peptide epitope immobilized by the anti-gp120 antibody.

[Indexed for MEDLINE]

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