Mimicry of the calcium-induced conformational state of troponin C by low temperature under pressure.
AUTOR(ES)
Foguel, D
RESUMO
Calcium binding to the N-domain of troponin C initiates a series of conformational changes that lead to muscle contraction. Calcium binding provides the free energy for a hydrophobic region in the core of N-domain to assume a more open configuration. Fluorescence measurements on a tryptophan mutant (F29W) show that a similar conformational change occurs in the absence of Ca2+ when the temperature is lowered under pressure. The conformation induced by subzero temperatures binds the hydrophobic probe bis-aminonaphthalene sulfonate, and the tryptophan has the same fluorescence lifetime (7 ns) as in the Ca2+-bound form. The decrease in volume (delta V = -25.4 ml/mol) corresponds to an increase in surface area. Thermodynamic measurements suggest an enthalpy-driven conformational change that leads to an intermediate with an exposed N-domain core and a high affinity for Ca2+.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=38207Documentos Relacionados
- Temperature dependence of calcium-induced fusion of sonicated phosphatidylserine vesicles.
- Molecular mechanism of the calcium-induced conformational change in the spectrin EF-hands.
- Photolabeling evidence for calcium-induced conformational changes at the ATP binding site of scallop myosin.
- Calcium-induced calcium release in rat sensory neurons.
- Calcium-induced calcium release in crayfish skeletal muscle.