This article compares soluble native protein expression from Wheat Germ Extract Plus and two E. coli expression systems using Flexi® Vector plasmids encoding 55 different human proteins. While only three of the proteins were expressed in the soluble fraction of E. coli cells, the number of proteins expressed using the E. coli T7 S30 Extract System for Circular DNA increased to 42. However, only 10 of those proteins were in the soluble fraction. In contrast, all 55 proteins were expressed in the soluble fraction of Wheat Germ Extract Plus, and nearly fourfold higher yields were achieved using the Wheat Germ Extract Plus in dialysis mode compared to batch mode.
Promega Notes 91, 21–25.