FIG. 3.
Effect of preincubation with aptamer or sCD4 on gp120 binding to immobilized receptors. BIAcore sensorgram overlays show the competition binding of (A) monomeric Ba-L gp120, (B) gp120-sCD4 complex, (C) gp120-aptamer B40 complex, and (D) gp120-sCD4-aptamer B40 complex to immobilized equimolar amounts of sulfated N-terminal peptide of CCR5 (S-peptide; solid line), desulfated N-terminal peptide of CCR5 (C-peptide; dotted line) and soluble human CD4 ectodomain (sCD4; dashed line) on a CM5 biosensor chip. The S-peptide and C-peptide are biotinylated at the C terminus and captured by use of streptavidin, while sCD4 is directly coupled via amine coupling. The horizontal I-shaped bars show the injection period of the analytes. RU, response units; SPR, surface plasmon resonance.