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Opening the Arg-Glu salt bridge in myosin: computational study
Ilya Kaliman1, Bella Grigorenko, Maria Shadrina
1Department of Chemistry, M. V. Lomonosov Moscow State University, Moscow, 119992, Russian Federation.
Physical Chemistry Chemical Physics : PCCP
|June 10, 2009
Summary
Computational models show that opening the Arg-Glu salt bridge in myosin is easier after adenosine triphosphate hydrolysis. This process, however, does not aid inorganic phosphate release via the back-door mechanism.
Area of Science:
- Biochemistry
- Computational Biology
- Molecular Biophysics
Background:
- Myosin's function in muscle contraction involves the hydrolysis of adenosine triphosphate (ATP).
- The Arg-Glu salt bridge is a key structural element in myosin's active site.
- Understanding the dynamics of this salt bridge is crucial for elucidating the myosin ATPase cycle.
Purpose of the Study:
- To computationally model the opening of the Arg-Glu salt bridge in myosin.
- To investigate the role of this salt bridge opening in relation to ATP hydrolysis and inorganic phosphate release.
Main Methods:
- Quantum mechanics-molecular mechanics (QM-MM) simulations were employed.
- Potential of mean force (PMF) calculations were performed to analyze the energy landscape.
- Structures of enzyme-substrate and enzyme-product complexes were utilized.
Main Results:
- The opening of the Arg-Glu salt bridge is significantly facilitated after the termination of the chemical reaction (ATP hydrolysis).
- Computational analysis indicates that opening the salt bridge does not promote the egress of inorganic phosphate through the proposed back-door mechanism.
Conclusions:
- The Arg-Glu salt bridge opening is a post-hydrolysis event that occurs readily.
- The back-door phosphate release mechanism is unlikely to be promoted by the opening of this specific salt bridge in myosin.
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