Optimization of determination conditions of nitrite reductase activity produced by Bacillus megaterium

In order to investigate and utilize the catalytic characteristics of nitrite reductase(NiR) produced by Bacillus megaterium,the determination conditions of NiR activity were optimized by buffers,electron donors and their concentrations,NaCl concentration,enzyme dosage,reaction temperature and time.The determination system(250μL)of NiR activity consisted of 0.1mol/L Na2HPO4-0.05mol/L citric acid buffer(pH6.0)125μL,1mol/L NaCl 15μL,3 electron donors including 0.05mol/L methyl viologen 7.5μL,0.05mol/L sodium thiosulfate 20μL and 0.15mol/L sodium dithionite 20μL,and enzyme 50μL.The reaction was performed at 35℃ for 1.5min.