Figure 7.

Fluorescence excitation and emission spectra for various T7 DNA polymerase E514Cou complexes. The excitation spectrum (red) has a maximum at 361 nm but also contains a smaller peak with a local maximum around 280 nm. Emission spectra were collected with excitation of the sample at 295 nm, first for the free enzyme (300 nm) with thioredoxin (6 µm) and Mg²⁺ (E, black). An excess of DNA_dd (400 nm) was added, resulting in a small increase in fluorescence for the binary complex (E + D_dd, blue). dATP (10 µm) was then added and resulted in a further increase in fluorescence for the ternary complex (E + D_dd + dATP, green). The emission maximum was at 447 nm.