Fig. 6.

SULT2A8 stability in the presence of cofactor and substrates. A: Trypsin limited proteolysis study. Purified SULT2A8 was coincubated with or without PAP and Na CDC as indicated in the trypsin digestion reactions. Digested proteins were electrophoresed by SDS-PAGE and detected by Coomassie blue staining. B: SULT2A8 WT and its mutants with substitution in the active site (upper panel) or loop 3 (lower panel) were coincubated with PAP, native/non-native substrates as indicated. The reaction was assayed using JBS Thermofluor Dye system. Fluorescent at 568 nm was detected with excitation wavelength of 483 nm under heating in a ramp rate of 1°C/min. T_m was calculated by solving the nonlinear fit through a Boltzmann sigmoidal equation and presented in means and standard deviation (n = 3). Differences of each ligand-treated protein were compared with its corresponding apo form using unpaired Student’s t-test, and significance was indicated in the text.