3.4.22.53 Mg2+ slight activation 643987 3.4.22.53 Mn2+ 1 mM, decreases the half-maximal Ca2+-requirement from 0.4 mM to 0.1 mM, decreases the Ca2+-requirement for maximal activity from 1.5 mM to 1 mM 644027 3.4.22.53 Mn2+ 5 mM 73.6% of the activation with 5 mM Ca2+. Synergistic activating effect with Ca2+ 644026 3.4.22.53 Mn2+ 5 mM, activates 644031 3.4.22.53 Mn2+ activates 644052 3.4.22.53 Na+ 5 mM, activates in presence of 5 mM Ca2+ 644031 3.4.22.53 Sr2+ 1 mM, decreases the half-maximal Ca2+-requirement from 0.4 mM to 0.1 mM, decreases the Ca2+-requirement for maximal activity from 1.5 mM to 1 mM. Synergistic activating effect with Ca2+ 644027 3.4.22.53 Sr2+ 2.5 mM, 66% of the activation obtained with Ca2+, maximal caseinolytic activity at 5.9 mM, half-maximal caseinolytic activity at 1.886 mM. Autolysis in presence of 5 mM Ca2+. The 80000 Da subunit is rapidly autolyzed in two smaller bands of 73000 Da and 69000 Da. The small subunit of 24000 da is degraded into three bands of 22000 Da, 19300 Da and 17800 Da. It is not clear whether autolysis is necessary for calpain to become proteolytically active 644052 3.4.22.53 Sr2+ 5 mM 91% of the activation with 5 mM Ca2+ 644026 3.4.22.53 Sr2+ 5 mM, activates 644031