SCREENING OF BANGLADESHI VEGETABLES FOR PEROXIDASE

Various locally available vegetables were screened for the enzyme peroxidase. The screening was performed mainly on daikon, cabbage, cauliflower; tomato and sweet potato etc. The juices of these vegetables were extracted and subjected to ammonium sulphate precipitation followed by dialysis to remove any adhere salts. The partially purified enzymes were then subjected to peroxidase assay. All the extracts from vegetables showed the presence of appreciable amount of peroxidase. In order to quantify, kinetic measurements of all the partially purified enzymes were performed using hydrogen peroxide as substrate and guaiacol (ortho-methoxy phenol) as color forming dye. The enzymatic activities of daikon, cabbage, cauliflower, sweet potato and tomato peroxidase having optical densities of 0.056, 0.139, 0.226, 0.139 and 0.089 at 280 nm were found to be 2.2898 U/ml, 3.4381U/ml, 1.1675 U/ml, 0.3741 U/ml and 0.1901 U/ml respectively. In order to compare the above result, the data have been normalized with respect to optical densities of cabbage. Thus, the partially purified enzyme having a optical density of 0.139 shows the peroxidase activity of 5.6836 U/ml, 3.4381 U/ml, 0.7181 U/ml, 0.3741 U/ml and 0.2969 U/ml respectively for daikon, cabbage, cauliflower, sweet potato and tomato. The present result indicates that the daikon peroxidase possess the highest enzymatic activity. The UV/Vis spectra of all vegetables showed characteristics Soret absorption band with a λ_max at 415 indicating the presence of heme molecule attached to apoenzyme.