Estimation of myosin denaturation rate when the medium includes chelate reagent
2009
Kuwahara, K. | Murata, M. | Konno, K.
It is required to estimate the myosin denaturation rate when myofibrils were heated in the presence of sodium citrate that chelates calcium ion leading to a loss of activation of Ca sup(2+)-ATPase. It was confirmed that addition of sodium citrate to Ca sup(2+)-ATPase assay medium suppressed the activity due to its chelating ability of calcium ion although the effect was inferior to EDTA, apparent Ca sup(2+)-ATPase activity measured with 0.5 M KCl was higher than that with 0.5 M NaCl indicating that addition of sodium citrate activated Ksup(+)-ATPase just like EDTA does. Therefore, KCl was replaced by NaCl in the Ca sup(2+)-ATPase reaction medium when chelate reagent was involved in the system. Calcium ion concentration should be increased to 15 mM from 5 mM to achieve a sufficiently high activity (about 80 %). The inactivation rates measured in the modified assay medium gave the same value as estimated in the original medium. We established the Ca sup(2+)-ATPase medium to estimate the thermal inactivation rate of myosin when the treated protein solution contains chelating reagent such as sodium citrate.
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