Ca2+-activated neutral protease (CANP) usually requires mM Ca2+ for activation. The sensitivity of CANP to Ca2+ is greatly enhanced by passing it through a casein-Sepharose column in the presence of Ca2+ ions. This conversion is ascribed to autolysis of CANP. The converted enzyme required 40 microM Ca2+ for 50% activation. Various properties of the converted enzyme were very similar to those of CANP-I, recently found in canine heart muscle. Names of "m-CANP" and "mu-CANP" are proposed for CANPs which require mM and microM order Ca2+ for inactivation, respectively.

No abstract

The conditions and process of autolysis of calcium-activated neutral protease (CANP) were examined. Optimal conditions for autolysis were the same as those required for expression of activity of CANP. The autolysis proceeded rapidly by a strictly limited proteolysis. During autolysis the molecular weight of CANP changed from 82 K (native CANP or mCANP) to 79 K and then 60 K. The 79 K and 60 K molecular species were both active at microM order of Ca2+ (muCANP), whereas the native CANP is active at mM order of Ca2+ (mCANP). Various proteases examined did not produce muCANP from mcanp under the conditions tested. Furthermore, muCANP did not yield muCANP from mCANP at lower Ca2+ concentrations where only muCANP was active. Therefore, muCANP is produced from mCANP only by the specific autolysis of mCANP.

Neutralization of endostatin worsens the symptoms and outcomes of MI in a rat model. The results imply that endogenous endostatin/collagen XVIII may suppress aberrant LV remodeling and heart failure after MI. (Circ J 2010; 74: 109 - 119).