Tryptophan fluorescence spectra of UV-B irradiated purified recombinant full length and N terminus truncated forms of <i>Arabidopsis</i> DNA Pol λ (AtPolλ).

<p>0.05 mg/mL of purified (A) full length recombinant Pol λ, (B) Del 1, (C) Del 2, and (D) Del 3 protein samples in a final volume of 600 μL of 50 mM Tric-HCl buffer, pH 7.5 (containing 1 mM β-ME and 1 mM PMSF) were irradiated with an UV-B dose of ~200 J/m² for the indicated time points in the dark at 25°C. Tryptophan fluorescence spectra of control and UV-B irradiated protein samples were measured using excitation wavelength of 295 nm. The emission wavelengths were set in the range between 300 to 400 nm with the emission scan speed of 240 nm/min. The 0-h time point served as the control. (E) Normalized tryptophan fluorescence intensity per tryptophan residue in full length recombinant Pol λ, Del 1, Del 2 and Del 3 fragments under control condition (without UV-B exposure). (F) Normalized tryptophan fluorescence intensity per tryptophan residue in full length recombinant Pol λ, Del 1, Del 2 and Del 3 fragments after 4 h of UV-B (~200 J/m²) at room temperature.