Characteristic thermal denaturation profile of myosin in the longitudinal retractor muscle of sea cucumber (Stichoupus japonicas)

This study elucidated thermal denaturation profile of myosin in sea cucumber longitudinal muscle. Sea cucumber myosin structure was different from fish at its head/tail junction which could not be cleaved by EDTA. However, sea cucumber myosin in salt-dissolved form could be cleaved into heavy meromyosin (HMM) and light meromyosin (LMM) segments. Although sea cucumbers lived in cold water, its myosin stability was comparable to tropical tilapia, more stable than rainbow trout (a cold water fish). Upon heating, the sea cucumber myosin lost its salt-solubility rapidly, even before losing its ATPase activity. The quick loss of salt-solubility suggested a quick denaturation at light meromyosin region as revealed by chymotryptic digestion. These results suggested that sea cucumber myosin is consisted of very stable head region and unstable tail region, which is important for choosing proper heating conditions for sea cucumber processing.