Thermostable aminopeptidase from local isolate of Bacillus stearothermophilus

Two of 63 isolates from different sources were very active in producing thermostable aminopeptidase. Comparing the two isolates, RR-2247 gave the highest enzyme activity and was identified as Bacillus stearothermophilus. The enzyme was isolated from the cells by a sonic vibration for 3 minutes at 20 KC/S. The enzyme shows optimum activity over the pH range of 7.5-8.0 at 65 degrees C. The apparent temperature optimum was about 70 degrees C. Addition of 0.0001 M Co2+ ions stabilized the enzyme in solution for 60 minutes at 80 degrees C. The heat of the reaction (delta E) was calculated to be +10,600 cal/mole. The standard entropy change (delta S) and the standard free energy change (delta G) were + 22.9 cal/mole/degree and -341 cal/mole at 50 degrees C. Amino acids composition and infra-red spectrum of the enzyme were also studied.