Purification and characterization of chitin deacetylase active on insoluble chitin from Nitratireductor aquimarinus MCDA3-3

The chitin deacetylase produced by marine strain Nitratireductor aquimarinus MCDA3-3 (NaCDA) was purified by using ammonium sulfate precipitation, Q Sepharose, and Superdex column chromatography. The purified NaCDA showed 75-fold purity, 50 U/mg specific activity with 28.5% yield. The purified CDA molecular weight was about 36 kDa. The temperature and pH of the purified enzyme were suiting at 30 degrees C and 8.0, respectively. The NaCDA was highly stable for a wide range of temperature 4 degrees C-25 degrees C and pH 6.0-9.0. Besides, increased enzyme activity was observed by introducing metal ions mainly Sr2+, Mg2+, and Na+. The enzyme was founded inhibited by Co-2 Ba2+, and EDTA at the value of 1 mM concentrations. On the other hand, NaCDA was shown an active activity behavior toward glycol chitin and chitin oligomers with a degree of polymerization more than four, any polymer below the chain such as trimer and dimer significantly reduce in the activity rate, and inactive with N-acetylglucosamine. Interestingly, NaCDA showed a high activity rate against insoluble chi tins and converting acetyls to deacetylated. The reduction of acetyls from 5626% and 22.88% of acetyl groups from alpha-chitin and beta-chitin, respectively. Hence, the NaCDA would be applicable in production chitosan toward mass production. (C) 2020 Published by Elsevier B.V.