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

Abstract

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 °C and 8.0, respectively. The NaCDA was highly stable for a wide range of temperature 4 °C-25 °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 Co²⁺, 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 chitins and converting acetyls to deacetylated. The reduction of acetyls from 56.26% and 22.88% of acetyl groups from ɑ-chitin and β-chitin, respectively. Hence, the NaCDA would be applicable in production chitosan toward mass production.

Keywords: Characterization; Chitin deacetylase; Insoluble chitin; Nitratireductor aquimarinus; Purification.