PROTEOLYTIC ACTIVITY AND VANADIUM INHIBITION IN ASCIDIAN BLOOD-CELLS

Proteolytic activity on azocasein was studied in the hemocytes of vana dium-accumulating ascidians (Phallusia mammillata and Ciona intestinal is) and iron-accumulating ascidians (Halocynthia papillosa and Microco smus sulcatus). A possible inhibitory role of vanadium on proteolytic enzymes was detected. The following results were obtained: 1. In the n eutral range M. sulcatus and C. intestinalis had optimal activity whil e H. papillosa showed only an activity shoulder, its activity being st rongest at alkaline pH. P. mammillata displayed no proteolytic activit y at all. Two types of individuals, with high and low activities, were present in H. papillosa at both pHs, and in M. sulcatus at alkaline p H. In C. intestinalis only individuals active at pH 6.5 were observed. 2. In the blood cell sonicate of H. papillosa and M. sulcatus the pro teolytic activity was inhibited by ethilene-diaminetetraacetate (EDTA) and N ethylmaleinimide (NEM). 3. P. mammillata blood cells sonicate i nhibited proteolytic activity of H. papillosa and M. sulcatus blood ce lls: this is attributed to the presence of large quantities of vanadiu m in the blood cells of P. mammillata. 4. Metavanadate, orthovanadate and vanadyl (IV) sulfate inhibited proteolytic activity of H. papillos a and M. sulcatus blood cells. The inhibitory effect showed dependence on the metal ion species, the pH, and the ascidian species assayed.