Ajinomoto’s Corynex™ expression system is a gram-positive, fast-growing soil bacterium that produces a high yield of recombinant protein secreted directly into the culture supernatant. The process is streamlined and generates fewer impurities than the traditional E. coli production system, according to the company.
“Many experiments that hardly produced protein in many traditional methods could be efficiently secreted in the Corynex,” reported staff scientist Yoshimi Kikuchi, Ph.D. “Furthermore, a protein that has complex structure, such as many disulfide bonds, homodimer, heterodimer, and multimer structures could be secreted as correctly folded structures possessing biological activity.” Therefore, refolding is not required.
Dr. Kikuchi said the purification process is simple. “Since there are minimal amounts of original secreted proteins in the culture supernatant of Corynebacterium glutamicum, the purity of the target protein secreted in the Corynex is very high.” Purification requires only six steps, according to Ajinomoto’s literature, whereas the production process using E. coli listed 12 steps.
As an example, Dr. Kikuchi elaborated, human IGF-1 could be produced efficiently using either the Corynex system or E. coli as a host strain. Using Corynex, it is produced in its correctly folded form and purified in only one-step chromatography.
“Using E. coli as the host strain, IGF-1 accumulates in the cytoplasm as an inclusion body, for which a re-folding process is required to obtain the active form. Furthermore, the re-folded IGF-1 is purified in four-step chromatography.”
Tests, in which living MCF-7 cells were measured four days after being stimulated by human epidermal growth factor produced naturally or by the Corynex system, showed nearly identical results.