Effects of Main Regulatory Proteins on the Heat-Induced Gel Formability of Myosin B

Abstract

The heat-induced gel formability of myosin B (natural actomyosin) and washed actomysin which prepared removing main regulatory proteins (tropomyosin, troponin) from natural actomyosin, were investigated. The results obtained were summerized as follows: (1) Elastic modulus, modulus of breaking elasticity and breaking energy of the heat-induced gel obtained from washed actomyosin were superior to those of myosin B in range of 50° to 100°C, and the drop in heat-sensitivity of washed actomyosin was observed. (2) The differences of rheological properties between both proteins reflected microstructure and solubility of gels, and those were closely affected by the form of network rather than protein quantities. Changes in minuteness and regulality of network were observed at 70°C and 100°C, respectively. (3) According to NaDodSO₄-Polyacrylamide gel electrophoresis patterns, myosin heavy chain, actin and myosin light chain 2 were responsible mainly for the heat-induced gel of washed actomyosin, whereas all of the constitutire proteins were responsible for that of myosin B. In the heat-induced gel at 100°C, S-1 fraction of myosin heavy chain was detected with both proteins. It is concluded from above observations that two regulatory proteins have no effect on the heat-induced gel formability of myosin B.