Fig. 3
From: Enantioselective reduction of sulfur-containing cyclic imines through biocatalysis

Colorimetric pH shift assay of 3-thiazolines. a Concept of colorimetric pH shift assay. Reduction of substrate catalyzed by imine reductase (IRED) and in situ-cofactor-regeneration by glucose dehydrogenase (GDH) results in a pH shift, due to formation of gluconic acid. This pH shift is visualized by bromthymol blue as indicator. b Substrate spectrum of 3-thiazolines examined in this work