Expressing optimization of argE gene and mechanism analysis of Zn²⁺ feeding time and its concentration

The cellular location of target gene argE expressed in recombinant BL21(DE3)-pET22b-argE was determined. The effects of Zn²⁺ effect feeding time and concentration on the biomass production and gene expression product activity were studied. The mechanism of Zn²⁺ effect was analyzed. The results showed that N-acetylornithine deacetylase coded by argE gene was over expressed and most of it was expressed as insoluble inclusion body, only a little as soluble expression. 1.0 g/L Mg²⁺ concentration improved both the biomass production and enzyme activity greatly. With different concentrations and feeding times, Zn²⁺ could bring about different influences. In contrast to the inhibition of feeding Zn²⁺at the cultivation beginning, addition of 1.0 mg/L Zn²⁺ after inducing for 2.5 h with 1.0% lactose reduced the inhibition on the growth and increased the enzyme activity. SDS-PAGE analysis and enzyme activity measurement proved that Zn²⁺ did not influence the expression rate, but the catalyst site of recombinant NAOase.