Engineering chitin deacetylase AsCDA for improving the catalytic efficiency towards crystalline chitin

Guang Yang; Zhihong Hu; Yuhan Wang; Hongjuan Mo; Shu Liu; Xiaoyue Hou; Xudong Wu; Hong Jiang; Yaowei Fang

doi:10.1016/j.carbpol.2023.121123

Engineering chitin deacetylase AsCDA for improving the catalytic efficiency towards crystalline chitin

Carbohydr Polym. 2023 Oct 15:318:121123. doi: 10.1016/j.carbpol.2023.121123. Epub 2023 Jun 16.

Authors

Guang Yang¹, Zhihong Hu², Yuhan Wang², Hongjuan Mo², Shu Liu¹, Xiaoyue Hou¹, Xudong Wu², Hong Jiang³, Yaowei Fang⁴

Affiliations

¹ College of Food Science and Engineering, Jiangsu Key Laboratory of Marine Bioresources and Environment, Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang 222005, China; Jiangsu Marine Resources Development Research Institute, Jiangsu Ocean University, Lianyungang 222000, China; Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China.
² College of Food Science and Engineering, Jiangsu Key Laboratory of Marine Bioresources and Environment, Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang 222005, China.
³ College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China. Electronic address: jh@ouc.edu.cn.
⁴ College of Food Science and Engineering, Jiangsu Key Laboratory of Marine Bioresources and Environment, Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang 222005, China; Jiangsu Marine Resources Development Research Institute, Jiangsu Ocean University, Lianyungang 222000, China; Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China. Electronic address: 2007000027@jou.edu.cn.

PMID: 37479438
DOI: 10.1016/j.carbpol.2023.121123

Abstract

Chitin deacetylase (CDA) catalyzing the deacetylation of crystal chitin is a crucial step in the biosynthesis of chitosan, and also a scientific problem to be solved, which restricts the high-value utilization of chitin resources. This study aims to improve the catalytic efficiency of AsCDA from Acinetobacter schindleri MCDA01 by a semi-rational design using alanine scanning mutagenesis and saturation mutagenesis. The quadruple mutant M11 displayed a 2.31 and 1.73-fold improvement in kcat/Km and specific activity over AsCDA, which can remove 68 % of the acetyl groups from α-chitin. Furthermore, structural analysis suggested that additional hydrogen bonds, contributing the flexibility of amino acids and increasing the negative charge in M11 increased the catalytic efficiency. The microstructure changes of α-chitin pretreated by the mutant M11 were observed and evaluated using ¹³C CP/MAS NMR spectroscopy, FT-IR spectroscopy, XRD and SEM, and the results showed that M11 more efficiently catalyzed the release of acetyl groups from α-chitin. This study would provide a theoretical basis for the molecular modification of CDAs and accelerate the process of industrial production of chitosan by CDAs.

Keywords: AsCDA; Chitosan; Crystalline chitin; Protein engineering; Semi-rational design.

MeSH terms

Catalysis
Chitin*
Chitosan*
Spectroscopy, Fourier Transform Infrared

Substances

Chitin
Chitosan
chitin deacetylase