Increased production of low molecular weight recombinant proteins in Escherichia coli

A general method for obtaining high-level production of low molecular weight proteins in Escherichia coli is described. This method is based on the use of a novel Met-Xaa-protein construction which is formed by insertion of a single amino acid residue (preferably Arginine or Lysine) between the N-terminal methionine and the protein of interest. The utility of this method is illustrated by examples for achieving high-level production of human insulin-like growth factor-1, human proinsulin, and their analogs. Furthermore, highly produced insulin-like growth factor-1 derivatives and human proinsulin analogs are converted to their natural sequences by removal of dipeptides with cathepsin C.