Studies on the Ca2+-activated neutral proteinase of rabbit skeletal muscle. I. The characterization of the 80 K and the 30 K subunits.

The structure of the calcium-activated neutral proteinase (CANP) from rabbit skeletal muscle was examined. The purified CANP was homogeneous as judged by disc gel electrophoresis, while it showed two bands (M.W.=80,000 (80 K) and 31,000 (30 K) on SDS-gel electrophoresis. After denaturation of CANP, each subunit was separated and could be renatured alone or in combination with the other subunit. The results indicate that all the machinary necessary for the proteolytic activity is present in the 80 K subunit, but for the full activity the existence of the 30 K subunit is required.