Development of an optimized refolding process for recombinant Ala–Glu–IGF-1

Denatured and reduced N-terminal extended insulin-like growth factor-1 (AE-IGF-1) was purified from Escherichia coli extracts and subjected to in vitro folding. The renaturation process was shown to be a function of the redox potential of the solution. Folding by different methods had no significant effect on the renaturation. A mammal yield of 60% (w/w) was obtained. The folded AE-IGF-1 was enzymatically converted to IGF-1. The major by-product (20% w/w) wasidentified as scrambled IGF-1