Figure 2.

Characterization of HPLC-purified cross-linked duplex 1^I6S-Et-S4U2 (a) by denaturing anion exchange HPLC (b, bottom) in comparison to the non-linked parent duplex (b, top). Alkylation at the sulfur atoms within the thio-nucleobases is confirmed by the wavelength shift and strong intensity reduction of the absorption band above 300 nm in the UV spectrum (c, solid) compared to the spectrum of 1^I6S∙2^U4S (dashed). The thermal stability of the cross-linked duplex 1^I6S-Et-S4U2 (d, solid) is drastically increased compared to 1^I6S∙2^U4S (dashed).