Abstract: As an extremely important biological information molecule, the synthesis of nitric oxide depends on nitric oxide synthase, so nitric oxide synthase plays an irreplaceable role in animals and plants, especially in the growth and development of plants. In this study, the nitric oxide synthase gene of marine bacterium Exiguobacterium aurantiacum JM-2 was cloned, the target gene and vector were digested and ligated by Bam HⅠ and Hind Ⅲ, and then by heat shock transformation method the target gene was transferred to E. coli Top 10 and BL-21, which was successfully expressed to obtain transformed strains. Then IPTG was used to induce protein expression and purify the protein, and finally the activity of the protein was determined and analyzed. The results showed that when the optimum concentration of IPTG in the medium was 0.1 mmol/L and the induction time was 5 min, the activity of nitric oxide synthase was the highest.

Key words: gene cloning, purification of protein, nitric oxide synthase, activity determination