Chitosan is a linear N-deacetylated derivative of chitin, soluble in acetic solutions. The deacetylation of chitin can be achieved enzymatically using chitin deacetylase (ChDa) (EC 3.5.1.41), which hydrolyses the N-acetamido groups of N-acetyl-D-glucosamine residues in chitin and chitosan. Complementary DNA (cDNA), which encodes ChDa, was isolated from M. rouxii s well as other fungi. Chitin deacetylase activity was detected in partially purified and concentrated crude extract of the protein from Mucor circinelloides IBT-83. Additionally, two open reading frames (ORF), putatively encoding ChDa, were identified and amplified from cDNA of this strain. Each ORF was molecularly cloned and sequenced. Amino acid sequences of ChDaI and ChDaII were predicted, using nucleotide sequences of these cDNA clones, and analysed by means of bioinformatics tools.
In the paper the thermal deactivation of chitin deacetylase separated from Absidia orchidis vel coerulea was investigated. Experiments were carried out at a temperature of 50ºC up to 24 hours. Three mechanisms of deactivation were tested: irreversible first-order, reversible firstorder, and three-parameters phenomenological model. It was found that the last one gave the best approximation of the deactivation process. The parameters of the model were evaluated and the model was also confirmed by independent experiments.