A Recombinant Monomeric Human Insulin Mutant with Resistance to Trypsin Design, Preparation and Characterization

By using a gapped duplex DNA method, the four amino acids on the B chain of insulin, i.e. B22Arg, B28Pro, B29Lys and B30Thr, were mutagenized simultaneously into B22Asp, B28Lys, B29Pro and B30Lys, respectively. The recombinant B22Asp B28Lys B29Pro B30Lys human insulin was obtained simply by the treatment with trypsin of the precursor that was expressed in yeast. This human insulin analog had only 6% of receptor binding activity as that of the porcine insulin, but retained 50% of in vivo biological activity, compared with the latter. The self-association ability of the mutant measured through FPLC gel filtration chromatography showed that it was in monomeric state. As a monomeric insulin analog with resistance to the trypsin digestion, this compound may be promising in practical application.