apo calbindin is more stable than either apo calmodulin or apo troponin
C. Thermal unfolding of apo calbindin seems to be only half comlete at 90
degrees Celsius, while the tryptic fragments of calmodulin unfold at 49
and 46 degrees Celsius. The tryptic fragments of troponin C unfold at 60
and 20 degrees Celsius. (Wendt, et al (1988) Eur. J. Biochem, 175 439-444. AND Brzeska, et al (1983) FEBS letters,
153 169-173)
The calcium-loaded states of calbindin, calmodulin, and troponin C are all
very stable. Their denaturation temperatures exceed 90 degrees Celsius,
and are therefore not experimentally accessible. (Same references as above)
Functional Substitution:
Neither the skeletal nor cardiac isoform of troponin C can effectively activate
most calmodulin targets. (George, et al (1990) J. Biol. Chem., 265 9228-9235)
Calmodulin does not successfully substitute for troponin C in skinned skeletal
muscle fibers. (Brandt, et al (1994) FEBS Letters, 353 99-102)
