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A cis proline turn linking two beta-hairpin strands in the solution structure of an antibody-bound HIV-1IIIB V3 peptide.
Tugarinov V; Zvi A; Levy R; Anglister J; Department of Structural
July 30, 1999
Nat Struct Biol. 1999 Apr;6(4):331-5. Unique Identifier : AIDSLINE

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.

JOURNAL ARTICLE Amino Acid Sequence Carbon Isotopes HIV Antibodies/*CHEMISTRY/*METABOLISM HIV Envelope Protein gp120/*CHEMISTRY/*IMMUNOLOGY/METABOLISM HIV-1/*CHEMISTRY Immunoglobulin Fragments/CHEMISTRY/METABOLISM Immunoglobulin Variable Region/CHEMISTRY/METABOLISM Models, Molecular Molecular Sequence Data Nitrogen Isotopes Nuclear Magnetic Resonance/METHODS Peptide Fragments/*CHEMISTRY/*IMMUNOLOGY/METABOLISM Proline/CHEMISTRY Protein Conformation Solutions Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S.