Sh. Bhosale et al., THERMOSTABILITY OF HIGH-ACTIVITY ALKALINE PROTEASE FROM CONIDIOBOLUS-CORONATUS (NCL-86.8.20), Enzyme and microbial technology, 17(2), 1995, pp. 136-139
Conidiobolus coronatus (NCL 86.8.20) produces high levels of protease
activity (30 U ml(-1)). The ease of microbe-free enzyme preparation an
d its compatibility with most of the commercial detergents are the adv
antageous features of Conidiobolus protease. The enzyme was stable at
28 degrees C for 20 h and at 40 degrees C for 1 h, but was completely
inactive on incubation at 50 degrees C for I h. Higher thermostability
is an important factor for the suitability of its application in dete
rgents. The effect of a wide variety of compounds was studied to enhan
ce the thermal stability of the protease by modification of its microe
nvironment. Urea (2-4 M), sodium dodecyl sulfate (1%), NaCl (200 mM),
and beta-mercaptoethanol (10 mM) did nor improve the stability of the
enzyme. Ethylene glycol (10%), glycerol (1%), sorbitol (800 mM), and P
EG-8000 (200 mM) had a marginal effect in preventing the thermal inact
ivation of the protease. Casein (0.5%) was also unable to increase the
stability of the enzyme at 50 degrees C. Addition of Ca2+ (25 mM) or
glycine (1 M) was effective in increasing the half-life of the enzyme
three-fold. The enzyme retained 43% of its activity at 50 degrees C in
the presence of Ca2+ and glycine. The enzyme showed compatibility at
50 degrees C with commercial detergents such as Revel and Ariel in pre
sence of Ca2+.