       Document 0573
 DOCN  M9620573
 TI    A helical epitope in the C4 domain of HIV glycoprotein 120.
 DT    9602
 AU    Robey FA; Kelson-Harris T; Roller PP; Robert-Guroff M; Peptide and
       Immunochemistry Unit, NIDR, National Institutes of; Health, Bethesda,
       Maryland 20892, USA.
 SO    J Biol Chem. 1995 Oct 13;270(41):23918-21. Unique Identifier : AIDSLINE
       MED/96025763
 AB    The fourth conserved domain of the human immunodeficiency virus type 1
       (HIV-1) envelope, the C4 region of glycoprotein 120 (gp120), is an
       amphipathic stretch of amino acids that, based on mutational analyses,
       constitutes a major component of the CD4 binding region in gp120. In the
       absence of crystallographic and NMR data on C4 in intact gp120, we
       sought to gain insight into C4's conformation and accessibility in gp120
       by taking an immunochemical approach. In this study, a peptomer composed
       of a repeat peptide of C4 amino acids 419-436 from gp120 of HIV-1MN was
       synthesized for use as a conformationally constrained immunogen.
       Circular dichroism studies disclosed that the polymerized peptide,
       peptomer-(419-436), in 0.01 M Na2HPO4 buffer, pH 7.4, at 25 degrees C
       contained a dominant alpha-helical structure (53 +/- 1%) compared with 2
       +/- 4% alpha-helical content for the monomeric peptide-(419-436). The
       peptomer in Ribi's adjuvant induced the production of rabbit antibodies
       that recognized recombinant and native gp120 but, consistent with the
       literature, the C4 peptide having no conformational constraints did not.
       The experimental results show that only those antibodies formed against
       a helical immunogen from C4 will recognize recombinant and native gp120,
       and, therefore, the results support the notion that C4 is an alpha-helix
       in gp120.
 DE    Amino Acid Sequence  Animal  Antibodies  Binding Sites, Antibody
       Circular Dichroism  DNA Mutational Analysis  Epitopes/*CHEMISTRY  Human
       HIV Envelope Protein gp120/*CHEMISTRY/*IMMUNOLOGY  HIV-1/*METABOLISM
       Molecular Sequence Data  Molecular Weight  Peptide
       Fragments/CHEMISTRY/CHEMICAL SYNTHESIS/IMMUNOLOGY  *Protein Structure,
       Secondary  Rabbits/IMMUNOLOGY  Recombinant Proteins/CHEMISTRY/IMMUNOLOGY
       Support, U.S. Gov't, P.H.S.  JOURNAL ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).

