The effects of some metal ions on the trypsin activity were studied (Table 2). Addition of CaCl2 to the assay medium enhanced the protease activity to 220%. However calcium at 5 mM increased the activity of the crude protease extract from goby to only 110% . Further, Mg2+ and Mn2+ exhibited a slight stimulatory effect on the enzyme. On the contrary, Mn2+ decreased the protease activity of the crude extract by 52.5%. It is known that calcium ion promote the formation of active trypsin from trypsinogen and stabilize trypsin against autolysis. Similarly, trypsins from other fish species were activated by calcium ion [13,27]. On the contrary, trypsin from pyloric ceca of the starfish Asterina pectinifera was neither activated nor stabilized by calcium ion .
Protease activity was not affected by Ba2+, NaCl and KCl at a concentration of 5 mM. The trypsin activity was reduced by Zn2+ to 10%. Cu2+ and Hg2+ completely inhibited trypsin activity.
Since CaCl2 enhances trypsin activity, the effect of its concentration on enzyme activity was also studied. As shown in Fig. 4b,maximum activity was obtained with 5 mM CaCl2 and there was 220% increase in the activity compared to that realized without CaCl2. Beyond 5 mM Ca2+, trypsin activity decreased. These results indicated that the enzyme require Ca2+ for its optimal activity. The calcium requirement for trypsin activity is highly specific since other metal ions (such as Mn2+, Mg2+, and Ba2+) are not able to enhance, or slightly stimulated the enzyme activity.
The effects of some metal ions on the trypsin activity were studied (Table 2). Addition of CaCl2 to the assay medium enhanced the protease activity to 220%. However calcium at 5 mM increased the activity of the crude protease extract from goby to only 110% . Further, Mg2+ and Mn2+ exhibited a slight stimulatory effect on the enzyme. On the contrary, Mn2+ decreased the protease activity of the crude extract by 52.5%. It is known that calcium ion promote the formation of active trypsin from trypsinogen and stabilize trypsin against autolysis. Similarly, trypsins from other fish species were activated by calcium ion [13,27]. On the contrary, trypsin from pyloric ceca of the starfish Asterina pectinifera was neither activated nor stabilized by calcium ion . Protease activity was not affected by Ba2+, NaCl and KCl at a concentration of 5 mM. The trypsin activity was reduced by Zn2+ to 10%. Cu2+ and Hg2+ completely inhibited trypsin activity. Since CaCl2 enhances trypsin activity, the effect of its concentration on enzyme activity was also studied. As shown in Fig. 4b,maximum activity was obtained with 5 mM CaCl2 and there was 220% increase in the activity compared to that realized without CaCl2. Beyond 5 mM Ca2+, trypsin activity decreased. These results indicated that the enzyme require Ca2+ for its optimal activity. The calcium requirement for trypsin activity is highly specific since other metal ions (such as Mn2+, Mg2+, and Ba2+) are not able to enhance, or slightly stimulated the enzyme activity.
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