These are modified to include the piece of human DNA containing instructions for making proinsulin . Proinsulin is the precursor for insulin. The bacteria multiplies and produces large quantities of human proinsulin in a fermentor . Bacteria are then killed by heat sterilization, leaving behind the proinsulin. Proinsulin is enzymatically cleaved to produce human insulin.
Enzymatic cleavage is the slicing of a molecule by a protein.
The solution is centrifuged to remove cell matter and purified by liquid chromatography and crystallization . Insulin is a hormone produced by the pancreas, and is essential for the regulation of glucose in the body. The pancreas of a diabetes patient has lost the ability to produce insulin.