Chitinase: purification and characterization from Alternaria brassicicola and its antibacterial activity

Chitinases, a class of enzymes found widely in organisms such as bacteria, yeasts, fungi, arthropods, actinomycetes, plants and humans, exhibit significant diversity in their molecular structure, catalytic mechanisms and substrate preferences. A newly characterized extracellular chitinase enzyme was purified from Alternaria brassicicola using methods including ammonium sulfate precipitation and gel filtration chromatography. The enzyme's molecular weight, determined via SDS-PAGE, was found to be 44 kDa. It displays optimal activity at a temperature of 35 °C and remains functional across a temperature range of 30-60 °C. The enzyme exhibits maximum activity at pH 6.6 and shows significant activity within a pH range of 4-8. Metal ion studies revealed that Cu²⁺, Ca²⁺ and Zn²⁺ inhibits its activity, while Mn²⁺ and Mg²⁺ enhances it. Furthermore, the enzyme demonstrates inhibitory activity against bacteria such as Staphylococcus aureus and Escherichia coli. These findings underscore its potential applications in various biotechnological and medical fields.