Improvement of Soluble Production of Reteplase in Escherichia coli by Optimization of Chemical Chaperones in Lysis Buffer

Development of Solubilization and Refolding Buffers

Overexpression of heterologous protein in prokaryotic host cells, such as Escherichia coli, usually leads to formation of inactive and insoluble aggregates known as inclusion bodies (IBs). Recovery of refolded and functionally bioactive proteins from IBs is a challenging task, and a unique condition (e.g., solubilizing and refolding buffers) for each individual protein should be experimentally obtained. Here, we present a simple protocol for development of solubilizing and refolding buffers for successful recovery of pure bioactive proteins from IBs.

L-ARGININE AND L-GLUTAMIC ACID INCREASE THE CONTENT OF PROTEIN C IN THE EARLY STAGES OF ISOLATION FROM DONOR PLASMA

Current large-scale production of blood-derived pharmacological preparations is aimed at expanding the list of products and deeper extraction of target proteins especially at the pre-purification stage. In particular, this problem becomes critical for the isolation of proteins like protein C (PC), which is present in plasma in trace amounts. Aim. We aimed to improve the buffer composition to minimize the interaction of PC with other proteins and lipids that are inevitably present in the stock material. Methods. The content of protein C in plasma and its derivatives was assessed by the amidolytic activity to the chromogenic substrate S2366. A decrease in homologous impurities and plasma enrichment with protein C was provided by selective bulk adsorption on DEAE-cellulose. Results. Here we describe that an equimolar mixture of two amino acids (L-arginine and L-glutamic acid) essentially increased the content of protein C at the stage of cryo-depleted plasma pre-purification, including initial dilution and subsequent enrichment of plasma with protein C due to selective bulk adsorption on DEAE- cellulose. Additionally, it was revealed that solutions of these amino acids, when combined, inhibit the induced amidolytic activity of protein C and increase its solubility (in contrast to other plasma proteases). Conclusion. Pre-adding of a mixture of amino acids L-arginine and L-glutamic acid to cryo-depleted plasma significantly optimizes the pre-purification stage of protein C, providing a 5-fold increase in its yield after elution from DEAE-cellulose.