[Thermo- and pH-stability of soluble and silichrome-80 immobilized proteinase from Bacillus subtilis].

The stability to heating and pH changing of two proteinases of Bacillus subtilis was studied. The preparations were: protosubtilin G10x with an activity of 21500 units/g and proteinase immobilized on silochrome C-80 with an activity of 3880 units/g. For protosubtilin G10x the pH optimum was 7.0-7.2. For the immobilized preparation 96-100% activity was found at pH 5.5-10.0. The difference between the two proteinase preparations was more distinct with respect to the temperature minimum. The initial preparation-protosubtilin G10x was more stable to low temperature and showed maximum activity at 40 degrees; the immobilized preparation was less active at low temperatures and showed maximum activity at 60-70 degrees. Protosubtilin G10x was more sensitive to pH changes, especially in the acid zone (pH 4.5). It was significantly activated at 30-40 degrees and was unstable at 50-60 degrees. The immobilized preparation was activated at 50- 60 degrees and was insensitive to pH changes in the range of 4.5 to 9.2 and temperature changes from 10 degrees to 40 degrees for 1.5-2.0 hours.