Acid-induced dimerization of skeletal troponin C.

摘要: We have investigated pH-dependent changes of the properties troponin C from rabbit skeletal muscle. At pH 7.5 this protein is a monomer and at 5.2 it dimer. In contrast, bovine cardiac remains essentially monomeric 5.2. Bovine brain calmodulin not dimer, but significantly aggregated same acidic pH. The dimerization was demonstrated by low-speed (16,000 rpm) sedimentation equilibrium measurements carried out 20 degrees polyacrylamide gel electrophoresis under nondenaturing conditions. Dimer formation inhibited in ultracentrifuge rotor speeds 30,000 40,000 rpm C, completely prevented speed 4 C. This temperature pressure dependence strongly suggests that hydrophobic bonding major factor promoting association intramolecular distance between Met-25 Cys-98 deduced fluorescence resonance energy transfer increased two upon lowering to 5.2, indicating transition which changed relatively compact conformation an elongated conformation. proton-induced increase related acid-induced protein.(ABSTRACT TRUNCATED AT 250 WORDS)