초록
<P>In the present study, the optimization of production and reaction conditions of polygalacturonase produced by a fungus<I>Byssochlamys fulva</I>MTCC 505 was achieved. The production of polygalacturonase with a considerable activity of 1.28 IU/ml was found when the culture was shaken at 30°C for 5 days in 100 ml of medium containing (w/v) 10 g/l pectin, 2 g/l NaNO3, 1 g/l KH2PO4, 0.5 g/l KCl, 0.5 g/l MgSO4. 7H2O, 0.001 g/l FeSO4. 7H2O, 0.001 g/l CaCl2. The best carbon and nitrogen source for this enzyme were pectin (1%) and Ca(NO3)2(0.1%), respectively. The enzyme gave maximum activity at incubation time of 72 h, temperature of 30°C and pH 4.5. During the optimization of reaction conditions, the enzyme showed maximum activity in sodium citrate buffer (50 mM) of pH 5.5 at 50°C reaction temperature for 15 minutes of incubation. The enzyme showed greater affinity for polygalacturonic acid as substrate (0.5%).<I>K</I>mand<I>V</I>maxvalues were 0.15 mg/ml and 4.58 μmol/ml/min. The effect of various phenolics, thiols, protein inhibitors and metal ions on the enzyme activity was investigated. The enzyme was quite stable at 4°C and 30°C. At 40°C the half life of the enzyme was 6 h and at 60°C it was 2 h.</P>