الفهرس 
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Abstract
Penicillin G acylase (PGA) (E.C.3.5.1.11) is an intracellular enzyme produced by E.coli ATCC13529 .PGA deacylates penicillin G to yield 6-aminopenicillinic acid (6-APA) which is used for the manufacture of semisyntheic penicillins.
The current study was designed to optimize the different conditions influencing the production and activity of PGA from E.coli ATCC 13529 and control them.
The main obtained results could be summarised as follow:
1- Different formula of growth media were designed to achieve the highest enzyme specific activity, the optimum formulated media were B and E .
2- Addition of phenylacetic acid (PAA) to the optimum growth media (B and E ) did not inhance enzyme activity using medium B, whereas it supressed the activity with a percentage of 16.5% by using medium E.
3- The best statistical factorial design for medium B -which gave the highest enzyme activity- contained 1% glucose, 8% lactose, 10% corn steep liquor and 0.3% PAA, the resulted specific enzyme activity from this formula was 8.76 U/gm.
4- Comparing the effect of using casein-whey medium with modified B medium on the specific PGA activity and it was found that enzyme activity increased five folds using casein-whey medium more than modified B medium.
5- Fortification of casein-whey medium with PAA during several fermentation periods resulted in the increasing of PGA production. The maximum enzyme activity level (16 U/ml) was achieved after 6 hours of fermentation priod with the addition of 3 gm/L of PAA.
6- The optimum time for sonicating microbial cells was 10 min., which released the largest amount of PGA enzyme (4.405 U/ml).
7- The optimum conditions of DAB assay method for the best measuring of PGA activity were incubation at 50˚ C for 30 min.
8- E.coli ATCC 13529 was capable of tolerating the presence of penicillin G and PAA in growth media with concentrations of 4000 and 2800 µM, respectively.
9- For purification of PGA enzyme, gel filtration with sephadex-G-200 was used. Fraction number seven gave both the highest O.D of protein and enzyme activity (U/ml) with values of 0.232 and 0.850, respectively.
10- Dialysis of the enzyme followed by gel filtration with sephadex-G-200 resulted in increasing of enzyme purity with 5.75 folds.
11- Activated chitosan was used for PGA immobilization, the loss of enzyme activity ranged from 0% in the second cycle to 79.2% after the 8th cycle.
Finally, it could be concluded from this study that casein-whey medium fortified with 3 gm/L of PAA was the best tested media for the production and activity of PGA from E.coli ATCC 13529, and the most suitable conditions for assaying enzyme by DAB method were incubation at 50° C for 30 sec. Gel filtration following dialysis of PGA gave high enzyme purity and activity, furthermore, immobilization on activated chitosan kept the enzyme activity till the eighth cycle.