[Expression constructs of inducible isoform of nitric oxide synthase in Escherichia coli cells]

In the present work we describe the construction of expression system for inducible murine macrophage nitric oxide synthase (iNOS) in E.coli. For this purpose a framework of translation iNOS was cloned in the expression vector pCWori +. As biosynthesis of active iNOS requires coexpression of calmodulin (CaM), for obtaining functional expression of this protein we conducted amplification of an appropriate site of the library total cDNA a frog Xenopus laevis, then plasmids for coexpression of calmodulin were constructed under a control tac and T7 promotors. Recombinant iNOS was functionally active as revealed by the analysis of CO-reduced spectrums, detection of derivation NO with the help of reaction conversion HbO2 in metHb, and also identification of a molecule NO by EPR method. The output of recombinant iNOS at usage of different constructions varied from 10 up to 22 mg/l culture, and specific activity was from 0.42 up to 0.64 U/mg of protein. These data coincide with the earlier published results of other investigators. It was established, that the expressed iNOS is associated to a membrane fraction of cells, thus in the 105,000 g-supernatant the activity of an enzyme is not detected. The data on membrane localization iNOS are inconsistent with general notion this enzyme is soluble.