Structural studies on synthetic peptides from the principal neutralizing domain of HIV-1 gp120 that bind to CD4 and enhance HIV-1 infection.

In previous studies we have demonstrated that synthetic peptides, corresponding to sequences in the (307-330) region of the gp120 principal neutralizing domain of different HIV-1 isolates are specifically recognized by a site distinct from the high affinity gp120-binding site of CD4. Interestingly, a peptide designed from the HIV-1 MN strain is able to enhance viral infection, while a HTLV-IIIB derived analogue is at least ten-fold less efficient and no effect is shown by other tested peptides. This enhancing effect occurs in the early step of infection and it is not strain restricted. A correlation between structure and biological functions evidenced by CD, FT-IR, and preliminary mono and bidimensional NMR is presented in this paper. The experimental data are compared to the predictions obtained by theoretical calculations.