登入選單

返回Google圖書搜尋

Structural and Thermodymanic Studies of the Thrombin-binding Aptamer and Related Quadruplexes

Chungfei Esther Tang

出版	University of California, San Francisco, 2006
URL	http://books.google.com.hk/books?id=pEhIrLX21WsC&hl=&source=gbs_api

註釋

Antiparallel quadruplexes contain guanine stretches that are antiparallel to each other, in which half of the nucleosides have the anti conformations about the glycosidic bonds and half possess the syn conformations. In contrast, the guanine stretches in the parallel topology are parallel to each other with all nucleosides in the anti conformation. Although the antiparallel fold is more prevalent, parallel quadruplexes are becoming increasingly common. The influence of individual nucleoside conformation on the overall folding topology was examined in order to understand the forces that determine the quadruplex fold. Selective substitution of rG for dG allowed us to reverse the antiparallel fold of the thrombin binding aptamer (TBA). In addition, this approach also converts a unimolecular quadruplex into a bimolecular one. The reverse substitutions of dG for rG in the all-RNA analogue of TBA confirmed the change in topology from parallel to antiparallel conformation as well as the change from bimolecular to unimolecular. Changing conformational properties of guanine nucleosides allows us to control the quadruplex folding topology.