Systems and methods for production of recombinant IL-11 in yeast

A method for producing interleukin 11 (IL-11), comprising:

• introducing an expression vector encoding for a recombinant IL-11 into a yeast, wherein the recombinant IL-11 is not in the form of a fusion protein;
• culturing the yeast in a culture media under conditions to induce expression of IL-11;
• following culturing of the yeast, removing solids from the culture media to produce a supernatant;
• contacting the supernatant with a polyethylene glycol having an average molecular weight of about 2,000 D to about 20,000 D in quantities sufficient to form a suspension comprising a precipitate, wherein the polyethylene glycol is present in the supernatant at from about 4% (w/v) to about 12% (w/v) after contacting;
• collecting the precipitate;
• solubilizing the precipitate in a solution comprising guanidine hydrochloride at a concentration of about 4M to 10M to produce a crude IL-11 solution;
• reducing the guanidine hydrochloride concentration to 0.7M or less at a pH of about 4 to about 12 and at an IL-11 concentration of 0.1 mg/ml to 10 mg/mL to produce a refolded IL-11 solution;
• contacting the refolded IL-11 solution with a cation exchange media;
• and
• eluting a purified IL-11 from the cation exchange media.