Chitin deacetylase

Abstract

Chitin deacetylase (CDA; E.C. 3.5.1.41) is an enzyme that catalyzes the hydrolysis of acetamido groups of N- acetylglucosamine in chitin, promoting the conversion to chitosan, a glucosamine polymer. In zygomycetous fungi, CDA has an important role in fungal growth, being involved in cell-wall chitosan biosynthesis in tandem action with chitin synthase (CS; E.C. 2.4.1.16), and it could also be involved in deacetylation of chitin oligosaccharides during autolysis after the action of endo-chitinase on cell walls. The CDA is also reported to be involved in ascospore formation in Saccharomyces cerevisiae. An alternative biological role involving the enzyme in plant-pathogen interactions has been suggested for CDA from Colletotrichum lindemuthianum, a plant pathogen, and the enzyme is extracellular and active on chitin oligomers. The CDA and chitosanase facilitate the entry of the fungus, Metarhizium anisopliae in to the host insect, Helicoverpa armigera. In the case of plant pathogens such as Uromyces viciae-fabae, and an insect pathogen, M. anisopliae chitin deacetylase is known to assist in self defense from host chitinases by changing the wall composition from chitin to chitosan. The purification and characterization of CDA and identification and characterization of CDA genes from different organisms have also been reported. Chitosan, a deacetylated product of chitin, is a natural polymer that has great potential in biotechnology and in the biomedical and pharmaceutical industries. Commercially, it is produced from chitin via a harsh thermo-chemical process that shares most of the disadvantages of a multi-step chemical procedure. It is environmentally unsafe and not easily controlled, leading to a broad and heterogeneous range of products. An alternative or complementary procedure exploiting the enzymatic deacetylation of chitin could potentially be employed, especially when a controlled and well-defined process is required. The different biotechnological applications of CDA will be discussed.