The 3-D complex structures of extracellular domain of human CD16 (FcgammaRIII) and hIgG1 or B88-9 were obtained by means of computer-guided molecular modeling, respectively. The binding epitopes were predicted and binding energy was calculated theoretically. The epitopes of human CD16 interacted with hIgG1 and B88-9 were different and the binding energy of B88-9 was stronger than hIgG1. The computer competing simulation results showed that B88-9 could bind to CD16 when CD16 was also bound by hIgG1, while IgG1 could not bind to CD16 after CD16 was bound by B88-9. By flow cytometry analysis, the competitive binding activity of B88-9 to CD16 with hIgG1 was evaluated. With the increasing concentrations of hIgG1, the binding activity of B88-9 was not interfered markedly. It suggested that hIgG1 could not inhibit the interaction of CD16 and B88-9 and the binding domain of hIgG1 and B88-9 on CD16 was different.

中文翻译：

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人CD16（FcgRIII）上结合表位的差异与hIgG1和单克隆抗体B88-9相互作用。

人CD16（FcgammaRIII）和hIgG1或B88-9的胞外域的3-D复杂结构分别通过计算机指导的分子建模获得。预测结合表位并从理论上计算结合能。人CD16与hIgG1和B88-9相互作用的表位不同，B88-9的结合能强于hIgG1。计算机竞争的模拟结果表明，当h16G1也与CD16结合时，B88-9可以与CD16结合，而当B8-9与CD16结合时，IgG1不与CD16结合。通过流式细胞术分析，评估了B88-9对CD16与hIgG1的竞争结合活性。随着hIgG1浓度的增加，B88-9的结合活性不会受到明显干扰。