Production of human interferon alpha-2b in Escherichia coli and removal of N-terminal methionine utilizing archaeal methionine aminopeptidase

Methionine is the first amino acid residue in most of the recombinant proteins and sometimes it is necessary to remove the starting methionine in order to get foreign proteins with wild type sequences. Recombinant human interferon alpha-2b was produced in Escherichia coli in insoluble form as inclusion bodies, which were solubilized and refolded. Analysis of the purified recombinant protein indicated that it consisted of two types of molecules, one type, in majority, having N-terminal methionine intact, whereas the other type, in minority, having the N-terminal methionine cleaved by methionine aminopeptidase of the host. Both species were separated by high performance liquid chromatography and N-terminal methionine of the remaining molecules was removed by utilizing methionine aminopeptidase from Pyrococcus furiosus in order to get similar form of the interferon alpha-2b as produced by human body. The methodology developed in this study can be extended to other proteins of pharmaceutical importance.