Kinetic study of free and immobilized protease from Aspergillus sp

In the present investigation partially purified alkaline protease from Aspergillus sp. As#6 and As#7 strains were entrapped in calcium alginate beads and characterized using casein as a substrate. Temperature and pH maxima of protease from As#6 strain showed no changes before and after immobilization and remained stable at 45C and pH 9, respectively. However km value was slightly shifted from 4.5mg/ml to 5 mg/ml. Proteases from As#7 strain showed shifting in pH optima to a more alkaline range (10.0) as compared with free enzyme (9.0). Optimum temperature for protease from As#7 strain showed changes after immobilization and shifted from 65C to 85C. However there was no significant effect on Km value but Vmax of immobilized protease from As#7 strain was also shifted from 200U/ml to 370U/ml. Immobilized protease from As#6 strain was reused for 3 cycles with 22% loss in its activity whereas immobilize protease from As#7 strain was reused for 3 cycles with 17% loss in its activity. Protease from As#7 strain has a higher affinity for the substrate and higher proteolysis activity than protease from As#6 strain. The present work concludes that Aspergillus As#7 strain may be a good source of industrial protease.