Medical Scientist Training Program and Graduate Program in Biophysics, ‡Department of Biochemistry, and §Department of Chemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
Biochemistry. 2013 Sep 17;52(37):6304-12. doi: 10.1021/bi400619m. Epub 2013 Aug 30.
Pancreatic-type ribonucleases show clinical promise as chemotherapeutic agents but are limited in efficacy by the inefficiency of their uptake by human cells. Cellular uptake can be increased by the addition of positive charges to the surface of ribonucleases, either by site-directed mutagenesis or by chemical modification. This observation has led to the hypothesis that ribonuclease uptake by cells depends on electrostatics. Here, we use a combination of experimental and computational methods to ascertain the contribution of electrostatics to the cellular uptake of ribonucleases. We focus on three homologous ribonucleases: Onconase (frog), ribonuclease A (cow), and ribonuclease 1 (human). Our results support the hypothesis that electrostatics are necessary for the cellular uptake of Onconase. In contrast, specific interactions with cell-surface components likely contribute more to the cellular uptake of ribonuclease A and ribonuclease 1 than do electrostatics. These findings provide insight for the design of new cytotoxic ribonucleases.
胰腺核糖核酸酶作为化疗药物具有临床应用前景，但由于其在人细胞中的摄取效率低下而受到限制。通过在核糖核酸酶表面添加正电荷，可以通过定点突变或化学修饰来增加细胞摄取，这一观察结果导致了核糖核酸酶摄取细胞取决于静电作用的假说。在这里，我们使用实验和计算方法的组合来确定静电作用对核糖核酸酶细胞摄取的贡献。我们专注于三种同源核糖核酸酶：Onconase（蛙），核糖核酸酶 A（牛）和核糖核酸酶 1（人）。我们的结果支持静电作用对于 Onconase 细胞摄取是必需的假说。相比之下，与细胞表面成分的特异性相互作用可能比静电作用更有助于核糖核酸酶 A 和核糖核酸酶 1 的细胞摄取。这些发现为设计新型细胞毒性核糖核酸酶提供了参考。
