抄録
To make clear the polymerization behavior of myosin heavy chain (HC) through SS bonding upon heating, SDS-PAGE and the measurement of total SH groups (TSH), reactive SH groups (RSH) and surface hydrophobicity were performed on those actomyosin (AM, 0.5% protein) from carp, flying fish and rabbit which were heated for 1h at temperatures ranging from 10 to 80°C.
Results were similar in common among three kinds of AM.
In the presence of EDTA (1mM), surface hydrophobicity and RSH content enormously increased during the heating at the temperature between 30 and 40°C followed by the gradual increase with the rise in temperature up to 80°C without the decrease in TSH.
In the presence of Cu2+ (6μM), TSH content decreased obviously with the rise in temperature above 30°C and RSH decreased above 40-50°C, although surface hydrophobicity behaved as in the presence of EDTA. HC dimer through SS bonding was observed up to 30°C, though its amount was unchanged without decrease in TSH upon heating. Above 30°C, the higher molecules than HC dimer such as trimer, tetramer and so on were found and the polymerization of HC was promoted with the rise in temperature. Actin was also polymerized above 30°C.
These results suggest that up to 30°C the dimer of HC was formed through the oxidation of SH groups without the unfolding of the protein and above 30°C HC polymer was formed along with the oxidation of SH groups which were emerged with the unfolding. In addition, it was suggested that actin is oxidized to high polymer above 30°C as well as HC.
