Protein Heterogeneity in Recombinant Protein Expression

Abstract

Recombinant proteins are commonly utilized in the drug discovery pipeline as a means of assessing the potential drug’s potency. However, when expressed, heterogeneity in the protein’s sequence and/or structure can occur, thereby affecting experimental results. Thus, it is important to assess the degree of heterogeneity during the expression and purification of recombinant proteins. Hence, this project focused on assessing the heterogeneity of purified recombinant E. coli DXP reductoisomerase (DXR, IspC) by comparing the trypsin digested fragments of the recombinant protein to a database. This was first accomplished by expressing, harvesting, and purifying the recombinant E. coli IspC. After purification, the protein was assessed for purity via SDS-PAGE. Then, trypsin digestion was performed on the purified protein by exposing them to 3 different ratios of trypsin for two different incubation times. The resulting fragments were run via SDS-PAGE and the results compared to an in-silico digest. Herein, we present the results of this analysis.