Peroxidase of Cedrela fissilis leaves: Biochemical characterization and toxicity of enzymatically decolored solution of textile dye Brilliant Sky-Blue G

Abstract

This work aimed at studying an alternative source of peroxidase for application in textile dye decoloration. Cedar leaf peroxidase (Cedrela fissilis) was characterized. The enzyme showed maximum activity conditions in the temperature range of 50 °C-62 °C and pH 5, using guaiacol as a substrate. For gallic acid as substrate, the maximum activity conditions were in the temperature range from 45 °C to 50 °C and in the pH range from 6.0 to 6.4. The KM, values, when used guaiacol and gallic acid as substrates, were 18.7 mM and 31 mM, respectively. The inactivation temperature was 85 °C. The enzymatic activity was not influenced by the presence of Na+, K+, Mg2+, Ca2+ and Zn2+ metal ions, but decreased in the presence of Cu2+ ion. Partial purification using acetone 65% (v.v−1) showed a purification factor of 18.7. The specific activity of crude and partially purified enzymatic extract was 6.78 U.mg−1 and 126.69 U.mg−1, respectively. The enzyme maintained about 90% of relative activity after one month when stored in an ultrafreezer. In the conventional freezer, relative activity decreased to approximately 50% in three weeks. Application of the partially purified extract on Brilliant Sky-Blue G textile dye removed 82.65% of the color when subjected to optimal reaction conditions. The treated dye solutions showed no phytotoxicity in L. sativa seeds, and there was a decrease in cytotoxicity in human blood cells. Cedar leaf peroxidase may be an alternative for the treatment of wastewater containing textile dyes.