Role of cooling process in the thermal aggregate formation by carp myosin rod

Carp myosin rod solution did not show detectable turbidity upon heating at 80 °C. Rod aggregation was detected only by high sensitive light scattering intensity and gel filtration analysis on Sepharose CL 4B. Roughly half of myosin rod was still monomeric for sample heated at 80 °C at 2 mg/mL. Prolonged heating at 80 °C did not increase the amount of aggregates. Aggregation was prominent at high concentration of rod. Rod aggregation was promoted by cooling of the heated rod solution. Heating at 80 °C completely unfolded the α-helix structure of rod. However, α-helix structure was significantly recovered by about 85% upon cooling. Unfolding and aggregation analysis revealed that complete unfolding of whole rod structure was needed for aggregation, and the cooling process accompanying refolding of helical structure was important for aggregate formation.