Dalrymple P N, Houston L L
Biochem J. 1980 Jun 15;188(3):941-4. doi: 10.1042/bj1880941.
Ricin, was nitrated with tetranitromethane and reduced with sodium dithionite. Of the 8.0 nitro groups incorporated, 3.2 were on the A chain and 5.1 were on the B chain. Nitrated ricin1 was somewhat less active than nitrated and reduced ricin1 in inhibiting protein synthesis in vitro, but both were highly inhibitory. However, the modified toxins were less than 1% as active as ricin in inhibiting protein synthesis in cultured cells. Indirect immunofluorescence assays demonstrated tha both modified toxins were specifically bound to the cell surface and could be displaced by galactose.
蓖麻毒素用四硝基甲烷硝化，并用连二亚硫酸钠还原。在掺入的8.0个硝基中，3.2个在A链上，5.1个在B链上。硝化蓖麻毒素1在体外抑制蛋白质合成方面比硝化并还原的蓖麻毒素1活性稍低，但两者都具有高度抑制性。然而，修饰后的毒素在抑制培养细胞中蛋白质合成的活性仅为蓖麻毒素的1%以下。间接免疫荧光分析表明，两种修饰后的毒素都能特异性结合到细胞表面，并且能被半乳糖取代。
