Proteolytic activity and vanadium inhibition in ascidian blood cells

Abstract

Abstract Proteolytic activity on azocasein was studied in the hemocytes of vanadium-accumulating ascidians (Phallusia mammillata and Ciona intestinalis) and iron-accumulating ascidians (Halocynthia papillosa and Microcosmus sulcatus). A possible inhibitory role of vanadium on proteolytic enzymes was detected. The following results were obtained: 1. 1. In the neutral range M. sulcatus and C. intestinalis had optimal activity while H. papillosa showed only an activity shoulder, its activity being strongest at alkaline pH. P. mammillata displayed no proteolytic activity 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 pH. In C. intestinalis only individuals active at pH 6.5 were observed. 2. 2. In the blood cell sonicate of H. papillosa and M. sulcatus the proteolytic activity was inhibited by ethilenediaminetetraacetate (EDTA) and N-ethylmaleinimide (NEM). 3. 3. P. mammillata blood cells sonicate inhibited proteolytic activity of H. papillosa and M. sulcatus blood cells: this is attributed to the presence of large quantities of vanadium in the blood cells of P. mammillata. 4. 4. Metavanadate, orthovanadate and vanadyl (IV) sulfate inhibited proteolytic activity of H. papillosa and M. sulcatus blood cells. The inhibitory effect showed dependence on the metal ion species, the pH, and the ascidian species assayed.