Fig. 7. Insulin reduction assay of GST-DPY-11 protein. (A) A time course of the enzymatic activity assayed at a fixed concentration (3 µM) of the tested proteins. (B) A comparison of the catalytic activities of the fusion protein and thioredoxin at different concentrations and a fixed reaction time of 20 minutes. Black squares represent the E. coli recombinant thioredoxin; white triangles represent the GST fusion protein of wild-type TRX domain; black triangles represent the mutant fusion protein with glycine 76 mutated to glutamic acid; white circles represent the GST alone and black circles, the buffer alone.