Mitchell D J, Kim D T, Steinman L, Fathman C G, Rothbard J B
Department of Neurology, Stanford University, USA.
J Pept Res. 2000 Nov;56(5):318-25. doi: 10.1034/j.1399-3011.2000.00723.x.
Homopolymers or peptides containing a high percentage of cationic amino acids have been shown to have a unique ability to cross the plasma membrane of cells, and consequently have been used to facilitate the uptake of a variety of biopolymers and small molecules. To investigate whether the polycationic character of these molecules, or some other structural feature, was the molecular basis for the effect, the ability of a variety of homopolymers to enter cells was assayed by confocal microscopy and flow cytometry. Polymers of L- or D-arginine containing six or more amino acids entered cells far more effectively than polymers of equal length composed of lysine, ornithine and histidine. Peptides of fewer than six amino acids were ineffective. The length of the arginine side-chain could be varied without significant loss of activity. These data combined with the inability of polymers of citrulline to enter cells demonstrated that the guanidine headgroup of arginine was the critical structural component responsible for the biological activity. Cellular uptake could be inhibited by preincubation of the cells with sodium azide, but not by low temperature (3 degrees C), indicating that the process was energy dependent, but did not involve endocytosis.
已证明含有高比例阳离子氨基酸的均聚物或肽具有穿越细胞质膜的独特能力，因此已被用于促进多种生物聚合物和小分子的摄取。为了研究这些分子的聚阳离子特性或其他一些结构特征是否是该效应的分子基础，通过共聚焦显微镜和流式细胞术测定了多种均聚物进入细胞的能力。含有六个或更多氨基酸的L-或D-精氨酸聚合物比由赖氨酸、鸟氨酸和组氨酸组成的等长聚合物更有效地进入细胞。少于六个氨基酸的肽无效。精氨酸侧链的长度可以改变而不会显著丧失活性。这些数据与瓜氨酸聚合物无法进入细胞相结合，表明精氨酸的胍基是负责生物活性的关键结构成分。细胞摄取可通过用叠氮化钠预孵育细胞来抑制，但不能通过低温（3摄氏度）抑制，这表明该过程是能量依赖性的，但不涉及内吞作用。
