| Abstract: | The relationship between the dynamic rheological properties of heat induced gels of actomyosin (natural actomyosin) and the denaturation of actin in actomyosin during storage without ATP at pH 6.0 and 0°C was investigated using biochemical and dynamic rheological measurements. The complex modulus of gels after heating actomyosin containing 0.5 or 1.5 M KCl (pH 6.0) at 80°C increased with increasing storage time. The dynamic rheological behaviour during heat gelation of actomyosin in 1.5 M KCl indicated that the first rheological transition peak in the 50–53°C range induced by the presence of F-actin gradually disappeared with increasing storage time. However, in 0.5 M KCl, this transition peak clearly remained even after 15 days. The time course of denaturation of actin in actomyosin treated with 1.5 M KCl at pH 6.0 showed an increase in the percent denaturation after the storage was started, and about 100% of the actin became denatured after 21 days. In the case of 0.5 M KCl, unlike 1.5 M, the denaturation of actin occurred quickly within the first 5 days and then did not proceed. A sigmoidal relationship was found between the percent denaturation of actin and the KCl concentration added, the greatest change occurring at KCl concentrations between 0.5 and 1.0 M. The data indicated that the change in the property of actin in actomyosin during storage at low temperature exerts a great influence on the viscoelasticity of heat-induced gels of actomyosin. |
