CHARACTERIZATION OF HUMAN DNA-LIGASE-I EXPRESSED IN A BACULOVIRUS-INSECT CELL SYSTEM

The baculovirus expression system used to overexpress human DNA ligase I (hLig I). Approx. 2 mg of recombinant hLig I was produced per 10(8) Spodoptera frugiperda Sf9 insect cells infected with the recombinant baculovirus. The optimum time point for the production of biologically active recombinant hLig I was 48 h post-infection. Lig I activity was demonstrated by auto-adenylating, polynucleotide joining and DNA rela xation assays. The baculovirus system has the advantage over previousl y described methods for producing hLig I of generating large amounts o f a full-length active protein.