Role of Neck Region in the Thermal Aggregation of Myosin

Abstract

Carp dorsal myosin formed oligomers that retained ATPase activity upon heating. Cleavage of the oligomeric myosin at subfragment-1 (S-1)/rod junction released monomeric S-1 and rod, indicating that ATPase retaining myosin associated near the S-1/rod junction. The digest also contained rod oligomers. Heating a mixture of S-1 and rod generated neither ATPase retaining S-1 oligomers nor rod oligomers. Electron microscopic observation of the heated myosin revealed that some oligomers were formed by associating at the S-1/rod joining region, exhibiting a recognized double head, probably ATPase retaining oligomers. No myosin oligomers associated at the tail region were observed, thus, rod aggregation would be formed at its very restricted region near the S-1/rod junction. Based on the findings, we proposed that the neck structure is important in the thermal oligomerization process of myosin.

Myosin denaturation in heated myofibrils of scallop adductor muscle

“…S-1 denaturation was much slower than rod denaturation at 0.5 M, which was opposite to the pattern found at 0.1 M. A slow decrease of salt solubility was well correlated to rod denaturation, and ATPase inactivation was explained by S-1 denaturation. As the monomeric myosin content decreased a little faster than S-1 denaturation, myosin formed active aggregates as suggested with carp myosin [13].…”

Effect of calcium ion on the thermal denaturation of subfragment-1 and rod regions of squid myosin upon the heating of myofibrils

“…Probably great stabilization of S-1 portion by Ca 2+ indirectly affected the denaturation of connecting rod region slightly. It is reported that rod denaturation as studied by aggregate formation was affected by connecting S-1, namely rod aggregates was remarkable when myosin was heated, while no aggregate was formed when S-1 and rod mixture was heated [22]. It was concluded that stabilizing effect of Ca 2+ on myosin is restricted to S-1 portion, and stability of rod portion is primarily unaffected by the presence of Ca 2+ .…”

Action of Ascorbic Acid on a Myosin Molecule Derived from Carp

“…This binding formation results in the connection of rod region, creating the network structure of myosin. [6][7][8][9] The myosin solution was incubated at 40 C for 60 min in the absence or presence of AsA, and thehelical contents were compared before and after heating (Fig. 4).…”

“…The present results indicate that AsA promotes the thermal gelation of myosin by which the S-1 region is packed via the formation of SS bridges. This binding formation brings out the connection of rod region, creating the network structure of myosin, [6][7][8][9] to become a gel such as heat-induced fish gel. Moreover, it was also confirmed that AsA does not trigger gel formation by bringing about a conformational change in myosin, and that it promotes gel formation according to the mechanism (Fig.…”

“…It is known that the S-1 region is packed through the formation of SS bridges. This bridge formation connects the rod regions, creating a network structure, [6][7][8][9] resulting in the formation of a gel such as heat-induced fish gel. Then we investigated to determine whether AsA promotes this thermal gelation, producing the beneficial effects.…”