A Novel Alkaline-Stable Chitin Deacetylase from Chitiniphilus eburneus for Eco-Friendly Preparation of Specific Deacetylated Products.

Chitin deacetylase is the key enzyme responsible for the biological deacetylation of chitin. However, its limited sources and low catalytic efficiency toward α-chitin present significant barriers to the bioproduction of chitosan. Herein, a chitin deacetylase Ce1425 sourced from Chitiniphilus eburneus was identified, which displayed optimal catalytic efficiency at pH 10.0 and 55 °C, maintaining 91.92% of its activity at pH 12.0. The presence of Co2+ enhanced its activity by 167.38%. Ce1425 exhibited the highest specific activity toward (GlcNAc)3 (8.45 U/mg) and was capable of catalyzing the deacetylation of α-chitin. 12 h of catalysis reduced the acetylation degree of α-chitin by 24.65%. Ce1425 could remove up to three acetyl groups from chitooligosaccharide substrates, facilitated by the interactions between the substrates and Asp-83, His-137, Trp-203, and His-232. These findings broaden the sources of chitin deacetylases and provide valuable insights for the biopreparation of specifically deacetylated chitosan and its oligomers.