Characterization of chitin deacetylase from fungus Absidia butleri dr

The chitin deacetylase enzyme that catalyses the conversion of chitin to chitosan via the deacetylation of N-acetyl- glucosamine residues has been found in a few Zygomycetes and insects. Currently, chitosan is produced from chitin through harsh thermochemical procedure that has their disadvantages. The development of a controllable process using the enzymatic deacetylation of chitinous materials presents an alternative process that enables, in principle, the preparation of novel chitosan polymers and oligomers. Here we report the partial purification of chitin deacetylase (CDAEC 3.5.1.41) from Absidia butleri dr, a local fungal isolate. The partially pure enzyme obtained will be used to further elucidate the properties of CDA. Homogenization of the mycelia to obtain the cell-free crude extract of CDA by grinding with acid washed-sand produced a lower yield (17.6 mU/mL) compared to the use of a homogenizer (21.6 mU/mL). However, the former was chosen in this study to obtain the crude CDA as the method gave less contaminating proteins. Through a combination of anion exchange and gel filtration chromatography, the crude CDA was isolated as two isoenzymes, designated CDA1 and CDA2. The isoenzymes have apparent native molecular masses of 97.6 kDa (CDA1) and 221.7 kDa (CDA2). The analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that CDA1 and CDA2 have yet to be purified to electrophoretic homogeneity. A modified method to determine the enzyme activity has also been described