Evaluation of the binding between potential anti-HIV DNA-based drugs and viral envelope glycoprotein gp120 by capillary electrophoresis with laser-induced fluorescence detection

The fusion of the human immunodeficiency virus (HIV) with the target cell w as assisted by the interaction between the viral envelope glycoprotein HIV- 1 gp120 and a chemokine receptor. Studies have shown that the efficiency of the binding depends on the presence of the V3 loop of the gp120 which is k nown to interact with polyanions, such as phosphorothioate oligodeoxynucleo tides (Sd, potential anti-HIV drugs). In this study, capillary electrophore sis with laser-induced fluorescence detection (CE-LIF) was used to systemat ically evaluate binding between Sd and HIV-1 gp120. A 25-mer fluorescently tagged phosphorothioate oligodeoxynucleotide (GEM) was employed as a probe to study this interaction. The dissociation constant (K-d) between GEM and gp120 was determined to be 0.98 nM by Scatchard analysis. The competition c onstants (K-c) of a set of Sd that compete with GEM for binding to gp120 we re also determined. The results showed that the interaction had a strong de pendence on the sulfur phosphorothioate backbone. Chain length and the sequ ence of Sd also affect the ability of binding to gp120. The ability to stud y the protein-drug binding in the solution with minimal sample consumption makes CE-LIF very attractive for biological studies. (C) 2000 Academic Pres s.