期刊
FRONTIERS IN BIOENGINEERING AND BIOTECHNOLOGY
卷 9, 期 -, 页码 -出版社
FRONTIERS MEDIA SA
DOI: 10.3389/fbioe.2021.747602
关键词
GH70 family; dextransucrase; iron dextran; low molar mass dextran; site-directed mutagenesis
资金
- Jiangsu Key Lab of Biomass-based Green Fuels and Chemicals Foundation [JSBEM2016010]
- Jiangsu Synergetic Innovation Center for Advanced Bio-Manufacture of China
Mutation of amino acids near the sucrose binding site of dextransucrase can affect the chain elongation process, making it possible to modulate dextran size.
Iron dextran is a common anti-anemia drug, and it requires low molar mass dextran as substrate. In this work, we selected 11 amino acid residues in domain A/B of DSR-M Delta 2 within a 5-angstrom distance from sucrose for site-directed mutagenesis by molecular docking. Mutation of Q634 did not affect the enzyme catalytic activity, but showed an obvious impact on the ratio of low molecular weight dextran (L-dextran, 3,000-5,000 Da) and relatively higher molecular weight dextran (H-dextran, around 10,000 Da). L-dextran was the main product synthesized by DSR-M Delta 2 Q634A, and its average molecular weight was 3,951 Da with a polydispersity index < 1.3. The structural characterization of this homopolysaccharide revealed that it was a dextran, with 86.0% alpha(1 -> 6) and 14.0% alpha(1 -> 4) glycosidic linkages. Moreover, L-dextran was oxidized with NaOH and chelated with ferric trichloride, and an OL-dextran-iron complex was synthesized with a high iron-loading potential of 33.5% (w/w). Altogether, mutation of amino acids near the sucrose binding site of dextransucrase can affect the chain elongation process, making it possible to modulate dextran size.
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