Effects of SH groups, ε-NH_2 groups, ATP, and Myosin Subfragments on Heat-induced Gelling of Cardiac Myosin and Comparison with Skeletal Myosin and Actomysin Gelling Capacity(Biological Chemistry)

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Heat-induced gelling characteristics of myosin-actin from cardiac and skeletal muscle were investigated under various conditions in a model system. The interaction between actin and myosin at weight ratios of 1:15〜1:9 from cardiac or skeletal muscle seemed to contribute to heat-induced gel strength at pH 6.0, but such interaction seemed to carry little significance in gel formation at pH 5.4. A decrease in gel rigidity of chemically modified myosin (PCMB-treated) and actomyosin (TNBS-treated actin and PCMB-treated myosin) suggested that certain thiol (SH) group of cysteine residues in myosin and ε-NH_2 groups of lysine residues in actin were involved in the development of gel on heating. However, the magnitude of difference in gel strength at pH 6.0 (< 1,000 dyn/cm^2) and at pH 5.4 (9,000dyn/cm^2) of SH-blocked myosin was indicative of the major contribution of electrostatic interactions in the gelation of myosin. The effects of ATP on the gelation of myosin and actomyosin were also pH dependent. Total rod and LMM subfragments of cardiac myosin formed respectively 2.6 times and 2-times stronger gel than produced by HMM subfragments at identical conditions in the model system, but S-1 subfragment formed extremely weak gels under those conditions, which suggested the importance of the "tail" segment of the myosin molecule in the heat-induced gelation process.
社団法人日本農芸化学会の論文
1988-01-23