Interaction between inducible nitric oxide synthase and calmodulin in Ca2+-free and -bound forms.
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.
Xiao
Han
H
Department of Biochemistry and National Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210093, People's Republic of China.
Zhou
Hui
H
Chen
Guifang
G
Liu
Shanli
S
Li
Genxi
G
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*
D002147:Calmodulin; D004800:Enzymes, Immobilized; D011094:Polyethyleneimine; D052247:Nitric Oxide Synthase Type II; D002118:Calcium