Salhany J M, Schopfer L M
Veterans Administration Medical Center, Omaha, Nebraska.
J Biol Chem. 1993 Apr 15;268(11):7643-5.
Considerable effort is being made to design anti-viral drugs for the human immunodeficiency virus type 1 (HIV-1) infection process. Some of this work has focused on CD4 protein, the HIV-1 receptor on T helper lymphocytes. One drug that binds to CD4 protein and inhibits both viral infection and growth is DIDS (4,4'-diisothiocyanato-2,2'-stilbenedisulfonate). DIDS is best known for its ability to inhibit erythrocyte band 3 anion exchange. Although the antiviral potency of DIDS is evident in vitro (IC50 approximately 30 microM), intravenous administration of DIDS should not be effective owing to the large number of band 3 molecules present on the red blood cell membrane (approximately 10(6)/cell), and to the very small Kd for DIDS binding to band 3 (approximately 30 nM). Therefore, we sought to identify other anion transport inhibitors that would bind weakly to band 3, but tightly to CD4 protein, and that could be administered to humans without significant toxic side effects. On the basis of our previous work with band 3 (Salhany, J. M., Rauenbuehler, P. B., and Sloan, R. L. (1987) J. Biol. Chem. 262, 15965-15973), we elected to study the binding of pyridoxal 5'-phosphate (PLP) to soluble CD4 protein. We have discovered that PLP binds surprisingly tightly to soluble CD4 protein (Kd = 45 microM), with a stoichiometry of about 1 mol of PLP/mol of protein. Furthermore, PLP binding was found to be competitive with DIDS for its binding site on soluble CD4 protein. These results suggest that PLP may be an effective anti-viral agent for the HIV-1 infection process.
人们正在付出巨大努力来设计用于治疗人类免疫缺陷病毒1型（HIV-1）感染过程的抗病毒药物。这项工作中的一些聚焦于CD4蛋白，即T辅助淋巴细胞上的HIV-1受体。一种与CD4蛋白结合并抑制病毒感染和生长的药物是DIDS（4,4'-二异硫氰酸根合-2,2'-二苯乙烯二磺酸）。DIDS最广为人知的是其抑制红细胞带3阴离子交换的能力。尽管DIDS的抗病毒效力在体外很明显（半数抑制浓度约为30微摩尔），但由于红细胞膜上存在大量的带3分子（约10⁶/细胞），以及DIDS与带3结合的解离常数非常小（约30纳摩尔），静脉注射DIDS应该不会有效。因此，我们试图鉴定其他阴离子转运抑制剂，它们与带3的结合较弱，但与CD4蛋白的结合紧密，并且可以在没有明显毒副作用的情况下施用于人类。基于我们之前对带3的研究工作（Salhany, J. M., Rauenbuehler, P. B., and Sloan, R. L. (1987) J. Biol. Chem. 262, 15965 - 15973），我们选择研究磷酸吡哆醛（PLP）与可溶性CD4蛋白的结合。我们发现PLP与可溶性CD4蛋白的结合惊人地紧密（解离常数 = 45微摩尔），化学计量比约为1摩尔PLP/摩尔蛋白。此外，发现PLP结合与DIDS在可溶性CD4蛋白上的结合位点存在竞争。这些结果表明PLP可能是HIV-1感染过程的一种有效抗病毒剂。
