A U.S. Patent for a “Process for Preparing Recombinant Insulin Using Microfiltration” was awarded to Merck on February 18th, 2020. The present invention is a process for producing insulin or insulin analog, wherein the process has a digestion step in which an aqueous solution of properly refolded pre-proinsulin or pre-proinsulin analog is digested with one or more proteolytic enzymes to produce an aqueous solution of insulin or insulin analog, digestion byproducts, and host cell impurities and a downstream purification or chromatography step, in which the insulin or insulin analog is separated from the digestion byproducts, and host cell impurities… Learn More