Studies into the scale-up of a process to produce biosynthetic insulin-like growth factor

Abstract

A recombinant insulin-like growth factor analog (Long-R3–IGF-I, 19921) is currently produced for industrial use as a component in mammalian cell culture media. Gradually expanding markets require that the existing production process be modified to allow increased throughput. The process is therefore examined and the key bottleneck identified as the ion-exchange recovery of refolded peptide. Theoretically, process throughput can be significantly increased with minimum expense by increasing the refolding concentration and by concentrating the refolded peptide prior to ion-exchange recovery. Experimental studies into the effect of refolding concentration on peptide yield are described and the results fitted to a model of competing first– and second-order reactions. An increase in the refolding concentration is presently uneconomical, due to a reduction in the yield of correctly refolded protein. However, concentrating the refolded peptide by ultrafiltration proved feasible. Using this result, the outline of a semi-continuous de-bottlenecked process is described which is capable of increasing the throughput ten-fold without major purchase of new equipment.