Molecular dynamics simulation of the interaction between dense-phase carbon dioxide and the myosin heavy chain

- The tertiary structure of the MHC in MWDS and MWS changed significantly.
- The secondary structure of the MHC in MWDS and MWS changed significantly, too.
- The MHC underwent greater structural changes in MWDS than in MWS.
- DPCD exerted a large effect on the MHC structure.
- Being hydrogen bond, electrostatic & hydrophobic interactions between CO2 and MHC.

Dense-phase carbon dioxide (DPCD) can induce myosin denaturation and aggregation and result in the formation of a gel. To explore the mechanism that DPCD induce myosin the formation of gels, molecular dynamics simulations were used to investigate the effects of DPCD on the structural properties of the myosin heavy chain (MHC, GenBank Accession No: BAM65721.1) from Litopenaeus vannamei. In addition, the interaction between the MHC and CO2 was explored under the coupling of pressure and temperature. To facilitate a better understanding and comparison, the structure of MHC was simulated in water at 0.1 MPa and 50 °C (called the myosin-water system, MWS) and in water and DPCD at 25 MPa and 50 °C (called the myosin-water-DPCD system, MWDS). The analysis of the root-mean-square deviation (RMSD) and root-mean-square fluctuation (RMSF) revealed that the conformation of the MHC in both MWDS and MWS changed significantly relative to its initial structure. Moreover, the results of the solvent-accessible surface area demonstrated that the MHC structure changes from a compact arrangement to a looser arrangement in both MWDS and MWS. Finally, the results from investigations into the secondary structures showed that the α-helix content of the MHC decreased, whereas the β-turn and random coil content increased. Greater overall structural variations of the MHC were observed in MWDS than those observed in MWS. DPCD exerts a substantial effect on the MHC structure because of its hydrogen bonding, electrostatic repulsion and hydrophobic interactions with the MHC.

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