A VERY-HIGH-DENSITY LIPOPROTEIN WITH CLOTTING ABILITY FROM HEMOLYMPH OF SAND CRAYFISH, IBACUS-CILIATUS

A very-high-density lipoprotein (VHDL) with a density of 1.27-1.29 g/m l was the most abundant lipoprotein in the hemolymph of the sand crayf ish Ibacus ciliatus. The VHDL isolated by a density gradient ultracent rifugation consisted of 94% protein and 6% lipid reflecting its high d ensity, and phospholipid was a predominant lipid component. The VHDL h ad an apolipoprotein of molecular mass 195 kDa and its N-terminal amin o acid sequence was identified as follows: LQPGLEYQYRYNGRVAA. This seq uence was similar to those of clotting proteins from the spiny lobster Panulirus interruptus and the freshwater crayfish Pacifastacus lenius culus. Transglutaminase and Ca2+ also induced the VHDL to clot. Consid ering large amounts of VHDL in the hemolymph of sand crayfish, the VHD L not only functions as lipid carrier but plays an important role in t he defense process of crustacea.