Protease activity in fractionated blood cells of the vanadium accumulatingascidian Phallusia mammillata

Proteolytic activity was studied in the fractionated blood cells of the van adium accumulating ascidian P. mammillata by separating the cells before me asuring their activity. Cells were separated to avoid vanadocyte breakdown and subsequent vanadium diffusion into the assay medium. Our study revealed activity in the morula cell extract that was obtained by sonication and Ce ntricon concentration. After removing part of the extract for enzyme activi ty assay the remainder was kept at 0 degrees C; it was later found that muc h of the protein in this latter fraction formed a sediment whereas the prot ease remained in solution. The serine-protease substrate specificity of the enzyme was measured and the results are discussed in relation to serine pr otease involvement in immune defense. (C) 2000 Elsevier Science Inc. All ri ghts reserved.