title: Interaction between inducible nitric oxide synthase and calmodulin in Ca2+-free and -bound forms.
abstract: We have obtained the first direct electrochemistry of full-length inducible nitric oxide synthase (iNOS) by entrapping the enzyme in polyethylenimine (PEI) film. The interaction between iNOS and calmodulin (CaM) was then studied, which revealed an enhanced electron-transfer reactivity of the enzyme facilitated by CaM. It was also found that interflavin electron transfer of iNOS could be activated by the binding of Ca2+-bound CaM. The formal potentials (E degrees ') of flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) were determined to be -470 and -284 mV vs SCE at pH 7, respectively. The effect of Ca2+ on the interaction between iNOS and CaM has been examined as well. CaM bound with adequate Ca2+ was shown to have a better capability to enhance the electron-transfer reactions within iNOS.
authors.affiliation: Department of Biochemistry and National Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210093, People's Republic of China.
authors.forename: Han
authors.initials: H
authors.lastname: Xiao
authors.forename: Hui
authors.initials: H
authors.lastname: Zhou
authors.forename: Guifang
authors.initials: G
authors.lastname: Chen
authors.forename: Shanli
authors.initials: S
authors.lastname: Liu
authors.forename: Genxi
authors.initials: G
authors.lastname: Li
mesh_terms: D000818:Animals; D002118:Calcium / Q000737:chemistry*; D002147:Calmodulin / Q000737:chemistry*; D004563:Electrochemistry; D004579:Electron Transport; D004800:Enzymes, Immobilized / Q000737:chemistry; D051379:Mice; D052247:Nitric Oxide Synthase Type II / Q000737:chemistry*; D011094:Polyethyleneimine / Q000737:chemistry; D025941:Protein Interaction Mapping / Q000379:methods*
chemical_list: D002147:Calmodulin; D004800:Enzymes, Immobilized; D011094:Polyethyleneimine; D052247:Nitric Oxide Synthase Type II; D002118:Calcium