African Journal of
Microbiology Research

  • Abbreviation: Afr. J. Microbiol. Res.
  • Language: English
  • ISSN: 1996-0808
  • DOI: 10.5897/AJMR
  • Start Year: 2007
  • Published Articles: 5233

Full Length Research Paper

Thermodynamics investigation of Ca2+ effect on Troponin-C (TnC): A QM/MM study

Mahmoud Raouf 1 and Leila Mahdavian2*
1Department of Physical Education, Doroud Branch, Islamic Azad University, P. O. Box: 133, Doroud, Iran. 2Department of Chemistry, Doroud Branch, Islamic Azad University, P. O. Box: 133, Doroud, Iran.
Email: [email protected], [email protected]

  •  Accepted: 23 June 2011
  •  Published: 09 September 2011


Troponin (Tn) is an essential protein in calcium ion settings of skeletal and heart muscle contractions. It has three subcategories (TnC, TnI, TnT) which are connected to filament actin by tropomyosin. TnC controls the calcium in muscle contraction and is the Ca2+-binding subunit of the troponin complex. ATP facilitates separation of myosin from actin filament, eventually making thick filament to slip off thin filament. This results in short sarcomere. In this study, it is investigated that thermodynamics properties increase concentrations of Ca2+ and temperature present in lactic acid. Quantum mechanical and molecular dynamics methods were used to analyze the structure and stability of TnC-Ca2+configuration. TnC-Ca2+ mutated active site in lactic acid and water solvent. Calcium ions approaching TnC caused twisting movement of TnC, so TnI-TnT eventually released the head of Myozin to actin. Increased lactic acid can increase calcium ion connection around TnC and decrease Ca to SR; increased temperature can increase metabolism and fatigue of skeletal muscles, emptying glycolysis and reducing muscle activity.


Key words: Troponin C (TnC), calcium ion (Ca2+), lactic acid, fatigue of skeletal muscles, QM/MM.