title: Synthesis and conformational studies of N-glycosylated analogues of the HIV-1 principal neutralizing determinant.
abstract: The principal neutralizing determinant (PND) of HIV-1 is found in the V3 loop of the envelope glycoprotein. Antibodies elicited by peptides from this region, containing the GlyProGlyArgAlaPhe (GPGRAF) sequence, were able to neutralize diverse HIV-1 isolates [Javaherian et al. (1990) Science 250, 1590-1593]. The GPGR tetrapeptide was predicted to adopt a type II beta-turn conformation. Earlier, we showed that glycosylation of synthetic T cell epitopic peptides at natural glycosylation sites stabilized beta-turns [Otvös et al. (1991) Int. J. Pept. Protein Res. 38, 467-482]. To evaluate the secondary structure modifying effect of the introduction of an N-glycosylated asparagine residue and to find a correlation between conformation and a possible PND potential, a series of glycopeptide derivatives, N(sugar) GPGRAFY-NH2 (4a-f), have been prepared, together with the parent peptides GPGRAFY-NH2 (2) and NGPGRAFY-NH2 (3), by solid-phase peptide synthesis [sugars: (a) beta-D-glucopyranosyl (Glc); (b) beta-D-galactopyranosyl (Gal); (c) Glc-beta(1----4)-Glc; (d) 2-acetamido-2-deoxy-beta-D-glucopyranosyl (GlcNAc); (e) 2-acetamido-2-deoxy-beta-D-galactopyranosyl (GalNAc); (f) GlcNAc-beta(1----4)-GlcNAc; sugars are attached through a beta (1----N beta) linkage to asparagine (N).] Peptides 2-4 were characterized by amino acid analysis, reversed-phase HPLC, and fast atom bombardment mass spectrometry. Circular dichroism (CD) and Fourier-transform infrared (FT-IR) spectroscopic studies were performed in trifluoroethanol (TFE) and water (D2O was used in FT-IR experiments). Nonglycosylated peptides showed significantly different CD spectra in aqueous and TFE solution.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Institute of Biophysics, Biological Research Center, Szeged, Hungary.
authors.forename: I
authors.initials: I
authors.lastname: Laczkó
authors.forename: M
authors.initials: M
authors.lastname: Hollósi
authors.forename: L
authors.initials: L
authors.lastname: Urge
authors.forename: K E
authors.initials: KE
authors.lastname: Ugen
authors.forename: D B
authors.initials: DB
authors.lastname: Weiner
authors.forename: H H
authors.initials: HH
authors.lastname: Mantsch
authors.forename: J
authors.initials: J
authors.lastname: Thurin
authors.forename: L
authors.initials: L
authors.lastname: Otvös
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D004797:Enzyme-Linked Immunosorbent Assay; D006020:Glycopeptides / Q000138:chemical synthesis / Q000737:chemistry / Q000276:immunology; D015488:HIV Antigens / Q000737:chemistry*; D015699:HIV Envelope Protein gp120 / Q000737:chemistry* / Q000276:immunology / Q000648:ultrastructure; D015497:HIV-1 / Q000276:immunology*; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D011487:Protein Conformation; D013055:Spectrophotometry, Infrared
chemical_list: D006020:Glycopeptides; D015488:HIV Antigens; D015699:HIV Envelope Protein gp120