Fig. 4.

Comparison of MALDI-TOF mass spectra of Dh3 and corresponding stabilised duplexes, and Dh4 at 1 h time point with 10% mouse serum at room temperature using matrix b. 50 μM solutions of Dh3 (1 + 2), Dh3 stabilised on one strand (using 2′-OMe modification to block RNAse A-like clipping at cleavage site; 2 + 3 and 1 + 4), Dh3 stabilised on both strands (3 + 4) and Dh4 (5 + 6) siRNA duplexes were incubated with 10% mouse serum for 1 h. Unstabilised strands 1 and 2 were rapidly degraded whereas the full length stabilised RNA strands 3 and 4, as well as strands 5 and 6, which do not have terminal UA sequences did not show extensive degradation at this time point. Note that a higher guide wire voltage was used in these experiments, which has the result of enhancing the intensities of lower molecular mass fragments.