Purification and characterization of catechol 1,2-dioxygenase of <i style="">Pseudomonas fluorescens </i>for degradation of 4-chlorobenzoic acid

Abstract

The degradation of<i style=""> </i>4-chlorobenzoic acid (4-CBA) by<i style=""> Pseudomonas fluorescens </i>IST8 was determined. The degradation of 4-CBA proceeded through an oxidative route to yield ortho ring cleavage enzyme, catechol 1, 2-dioxygenase. The cell free extract fractionated by DEAE-cellulose ion-exchange and gel filtration chromatography showed two different fractions of catechol 1,2-dioxygenase with an expected molecular weight of 62 and 48 kDa, respectively. The catechol 1, 2-dioxygenase in the fractions I and II was purified to about 22.3 and 36.5 fold by using purification steps. The <i style="">p</i>H and temperature optima for enzyme activity were 6.5 and 25°C, respectively. The purified protein on SDS-polyacrylamide gel electrophoresis showed molecular weights of 28 and 24 kDa, indicating dimeric nature of the enzyme.