Biochemical characterization of a novel bifunctional alginate lyase from Microbulbifer arenaceous

Jun Jiang; Zhengqiang Jiang; Qiaojuan Yan; Susu Han; Shaoqing Yang

doi:10.1016/j.pep.2023.106372

Biochemical characterization of a novel bifunctional alginate lyase from Microbulbifer arenaceous

Protein Expr Purif. 2024 Jan:213:106372. doi: 10.1016/j.pep.2023.106372. Epub 2023 Sep 17.

Authors

Jun Jiang¹, Zhengqiang Jiang¹, Qiaojuan Yan², Susu Han¹, Shaoqing Yang³

Affiliations

¹ College of Food Science and Nutritional Engineering, China Agricultural University, No.17 Qinghua East Road, Haidian District, Beijing, 100083, China.
² Key Laboratory of Food Bioengineering (China National Light Industry), College of Engineering, China Agricultural University, No.17 Qinghua East Road, Haidian District, Beijing, 100083, China.
³ College of Food Science and Nutritional Engineering, China Agricultural University, No.17 Qinghua East Road, Haidian District, Beijing, 100083, China. Electronic address: ysq@cau.edu.cn.

PMID: 37717719
DOI: 10.1016/j.pep.2023.106372

Abstract

Bio‒production of alginate oligosaccharides (AOSs), a type of functional food additive, is a promising way for green utilization of algae, in which alginate hydrolyzing enzymes play a key role. A novel alginate lyase gene (MiAly17A) from a marine bacterium Microbulbifer arenaceous was heterologously expressed in E. coli. The coding sequence of the gene shared the highest identity of 86% with a polysaccharide lyase (PL) family 17 alginate lyase (AlgL17) from Microbulbifer sp. ALW1. The recombinant enzyme (MiAly17A) was purified and biochemically characterized. MiAly17A showed maximal enzyme activity at 40 °C and pH 7.5, respectively. It was stable at the temperatures below 35 °C and within pH 5.0-8.0. The enzyme activities were increased by 5.3 and 5.6 folds in the presence of 100 mM of K⁺ and Na⁺, respectively. MiAly17A was bifunctional and could hydrolyze sodium alginate to release unsaturated monosaccharides and oligosaccharides with degrees of polymerization (DP) 2-7. The enzyme catalyzed the cleavage of glycosidic bonds from the non-reducing ends and the backbone of the tested oligosaccharides (DP ≥ 4), exhibiting both exolytic and endo-lytic activities. Moreover, MiAly17A was used for the production of alginate oligosaccharides from sodium alginate, and the highest conversion ratio of 68% was obtained. The unique properties may possess the enzyme great potential for preparation of alginate oligosaccharides.

Keywords: Alginate lyase; Alginate oligosaccharides; Characterization; Expression; Hydrolysis pattern.