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  • 1
    ISSN: 1573-5001
    Keywords: Amaninamide ; Correlation time ; Evaluation of errors ; Interproton distances ; NOESY ; ROESY ; 2D NMR ; Peptides ; Cross-relaxation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary We have analyzed a combined use of the two-dimensional nuclear Overhauser effect in the laboratory frame (NOESY) and in the rotating frame (ROESY) to determine interproton distances and correlation time in medium-sized rigid molecules (Davis, 1987). This method can be applied in the intermediate motional regime, 0.2 〈 ωoτc, 〈 5, (τc, correlation time, (ωo resonance frequency). Error limits depend on the motional regime and are smallest near ωoτc=1.14. The method was tested on six geminal proton pairs in the bicyclic octapeptide (S-deoxo-γ-[R]-OH-Ile3 amaninamide, Mw =870) for which at 297 K in DMSO, a correlation time of 1.0 ns, with a standard deviation of 0.12 ns, and an interproton distance of 1.87 Å, with standard deviation of 0.04 Å, are obtained.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1075-2617
    Keywords: gp120/CD4 interactions ; HIV-1 PND ; conformation by CD and NMR ; solid-phase peptide synthesis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of peptides patterned on the principal neutralizing domain of the HIV-1 envelope glycoprotein gp120 have been synthesized by solid-phase techniques. Interestingly, in vitro experiments have shown that some of these peptides specifically interact with CD4 and, in particular, that the peptide corresponding to the sequence 307-330 of the HIV-1 MN isolate was able to enhance infection in a dose- specific and not a strain-restricted way. To bypass problems observed in preliminary runs, several peptides were synthesized by both Fmoc and Boc chemistry. Comparison of the two strategies has allowed the set up of convenient protocols for the preparation of the target peptides in good yield, and with the high-purity grade needed for biological and physicochemical studies. Since the biological effects were present in the carboxyl-free C-terminal linear peptide but not in the amidated C-terminal analogue, preliminary conformational studies by circular dichroism and nuclear magnetic resonance techniques were also performed in an attempt to correlate these effects with possible contributions of structured conformations as predicted by theoretical calculations. The possibility of a β-turn structure for the crucial Gly-Pro-Gly-Arg sequence has been confirmed by 2D NMR experiments. Ongoing studies suggest the exploitation of the activating properties of the MN-derived peptides to design a more sensitive and innovative serological test based on the virus itself and not on anti-HIV antibodies, as is the case for the large majority of tests currently in use. © 1997 European Peptide Society and John Wiley & Sons, Ltd.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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