Optimization of surface plasmon resonance based assay for investigating T-antigen helicase activity

Due to the increasing number of helicases shown to unwind quadruplex DNA structures in addition to duplex DNA, the biological significance of this activity is currently under investigation. One limitation of traditional gel analysis of helicase activity is the inability to effectively monitor unwinding of intramolecular G-quadruplex DNA substrates. Optimization of our novel SPR-based assay for monitoring the helicase activity of simian virus 40 (SV40) large T-antigen (T-ag) was undertaken to explore limitations and improvements in the ability to investigate G-quadruplex helicase activity. Although T-ag helicase was used, the assay is general in nature. An improved method for assessing unwinding of intramolecular G-quadruplex DNA substrates was developed.