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Pull-down of Calmodulin-binding Proteins
Published on: January 23, 2012
Interaction between inducible nitric oxide synthase and calmodulin in Ca2+-free and -bound forms
Han Xiao1, Hui Zhou, Guifang Chen
1Department of Biochemistry and National Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210093, People's Republic of China.
Journal of Proteome Research
|March 8, 2007
Summary
Researchers achieved direct electrochemistry of inducible nitric oxide synthase (iNOS) using polyethylenimine (PEI) films. Calmodulin (CaM) binding enhanced iNOS electron transfer, particularly with Ca2+-bound CaM.
Area of Science:
- Biochemistry
- Electrochemistry
- Enzyme kinetics
Background:
- Inducible nitric oxide synthase (iNOS) is a crucial enzyme in biological systems.
- Understanding iNOS electrochemical properties is vital for its functional characterization.
- Calmodulin (CaM) is a known calcium-binding protein that modulates enzyme activity.
Purpose of the Study:
- To establish direct electrochemistry for full-length iNOS.
- To investigate the interaction between iNOS and CaM and its effect on enzyme activity.
- To determine the formal potentials of the flavin cofactors within iNOS.
Main Methods:
- Enzymatic electrochemistry using polyethylenimine (PEI) film entrapment.
- Electrochemical analysis of iNOS-CaM interactions under varying Ca2+ conditions.
- Determination of formal potentials for FAD and FMN cofactors.
Main Results:
- First direct electrochemistry of full-length iNOS successfully obtained.
- CaM binding significantly enhanced iNOS electron-transfer reactivity.
- Ca2+-bound CaM further activated interflavin electron transfer within iNOS.
- Formal potentials for FAD and FMN were determined as -470 mV and -284 mV vs SCE at pH 7.
Conclusions:
- Direct electrochemistry provides a powerful tool for studying iNOS.
- CaM acts as a positive allosteric effector, enhancing iNOS electrochemical activity.
- Ca2+ concentration is critical for CaM's ability to modulate iNOS function.
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