Figure 3.

Efficiency of an siRNA is determined at two points of the RNAi pathway. (1) A strand bias exists that is defined by the intrinsic thermodynamic properties of the siRNA duplex, that is, by the relative stability of both ends. (2) A highly ordered structure may have a detrimental influence on the hybridisation of the siRNA/RISC to its target site and may therefore reduce the efficiency of the silencing process, even in cases in which the intended antisense strand is favored for incorporation into RISC. (Reprinted with slight modifications from the Journal of Molecular Biology; see [42], with kind permission from Elsevier.)