PRODUCTION OF HUMAN NORMAL ADULT AND FETAL HEMOGLOBINS IN ESCHERICHIA-COLI

A hemoglobin expression system in Escherichia coli is described, In or der to produce authentic human hemoglobin, we need to co-express both methionine aminopeptidase and globin genes under the control of a stro ng promoter, We have constructed three plasmids, pHE2, pHE4 and pHE7, for the expression of human normal adult hemoglobin and a plasmid, pHE 9, for the expression of human fetal hemoglobin, in high yields, The g lobin genes can be derived from either synthetic genes or human globin cDNAs. The extra amino-terminal methionine residues of the expressed globins can be removed by the co-expressed methionine aminopeptidase, The heme is inserted correctly into the expressed alpha-globin from ou r expression plasmids. A fraction (similar to 25%) of the heme is not inserted correctly into the expressed beta- or gamma-globin, However, the incorrectly inserted hemes can be converted into the correct confo rmation by carrying out a simple oxidation-reduction process on the pu rified hemoglobin molecule, We have investigated the functional proper ties of the expressed hemoglobins by measuring their oxygen-binding pr operties and their structural features by obtaining their H-1-NMR spec tra, Our results show that authentic human normal adult and fetal hemo globins can be produced from our expression plasmids in E.coli and in high yields. Our expression system allows us to design and to produce any recombinant hemoglobins needed for our research on the structure-f unction relationship in hemoglobin.