ENDOTHELIN-CONVERTING ENZYME - THE BINDING OF METAL-IONS

The metal ion of endothelin-converting enzyme (ECE) was investigated b y inhibiting the enzyme with ethylenediaminetetraacetic acid (EDTA) an d restoring activity by adding divalent metal salts in quantities less than the concentration of EDTA. Under these conditions, only metal io ns that bind to ECE with high affinity can affect the enzyme. The ferr ous enzyme had an activity of 76% relative to the native enzyme, the m anganous enzyme 76%, the nickelous enzyme 77%, the cupric enzyme 17%, the zinc enzyme 98% and the cobaltous enzyme 122%. Of these first tran sition series elements only zinc can be the metal of the native enzyme . The zinc enzyme has the same K(m) and turnover number as the native enzyme. (C) Munksgaard 1993.