Lilly's experience in manufacturing human insulin in E. coli using rDNA technology is well documented (6, 23, 50-54). Commercial recombinant human insulin was initially made by a chain combination procedure (28), then four years later in 1986 via the proinsulin route (24). In this latter process a 277-residue chimeric fusion protein (Trp LE'- Methionine-Human Proinsulin) is expressed in E. coli followed by chemical cleavage at methionine with cyanogen bromide to release human proinsulin mixed disulphides. Human insulin is obtained subsequent to appropriate folding, enzymatic transformation, large-scale purification and crystallisation (55, 56).
Insulin lispro is manufactured in essentially the same manner as human insulin with a few exceptions. The expression product from fermentation is a smaller precursor molecule with a shorter amino terminal extension that is removed enzymatically to yield Lys Pro -human proinsulin. Insulin lispro is liberated from proinsulin by hydrolysis with trypsin and carboxypeptidase B (24), chromatographically purified, and finally crystallised in the presence of Zinc and phenol (47). As with recombinant human insulin (6), a complex battery of analytical tests were used to evaluate insulin lispro during the research, development, and analytical control of the drug. These are listed below. Those tests with an asterisk are used routinely as quality control checks for each batch of bulk crystals to assure high product quality.
Was this article helpful?