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Keywords = diacetylchitobiose deacetylase

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18 pages, 2691 KiB  
Article
Structural, Thermodynamic and Enzymatic Characterization of N,N-Diacetylchitobiose Deacetylase from Pyrococcus chitonophagus
by Katarzyna Biniek-Antosiak, Magdalena Bejger, Joanna Śliwiak, Daniel Baranowski, Ahmed S. A. Mohammed, Dmitri I. Svergun and Wojciech Rypniewski
Int. J. Mol. Sci. 2022, 23(24), 15736; https://doi.org/10.3390/ijms232415736 - 12 Dec 2022
Cited by 3 | Viewed by 2218
Abstract
Chitin is a major source of energy and macroelements for many organisms. An important step in its degradation is the deacetylation of chitin or its fragments. Deacetylase from the extremophile Pyrococcus chitonophagus has been analyzed by X-ray crystallography, small-angle X-ray scattering, differential scanning [...] Read more.
Chitin is a major source of energy and macroelements for many organisms. An important step in its degradation is the deacetylation of chitin or its fragments. Deacetylase from the extremophile Pyrococcus chitonophagus has been analyzed by X-ray crystallography, small-angle X-ray scattering, differential scanning calorimetry, isothermal titration calorimetry and NMR to determine its structure, thermodynamics and enzymatic properties. It is a hexameric, zinc-containing metalloenzyme that retains its structural integrity up to temperatures slightly exceeding 100 °C. It removes the acetyl group specifically from the non-reducing end of the sugar substrate. Its main substrate is N,N-diacetylchitobiose but it also active, at a reduced level, toward N-acetyl-d-glucosamine or a trimer of N-acetyl-d-glucosamine units. Crystallographic analysis includes the structure of the enzyme with its main substrate approaching the active site in a monodentate manner, replacing the single water molecule that is bound at the Zn2+ cation when the ligand is absent. The Zn2+ cation remains tetrahedrally coordinated, with three of its ligands provided by the protein’s conserved His-Asp-His triad. The crystal structures are consistent with the reaction mechanism proceeding via an anhydride intermediate. Hydrolysis as the first step cannot be ruled out in a hydrated environment but no defined ‘hydrolytic water’ site can be identified in the analyzed structures. Full article
(This article belongs to the Special Issue Thermophilic and Hyperthermophilic Microbes and Enzymes 2.0)
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13 pages, 2189 KiB  
Article
A Two-Step Cross-Linked Hydrogel Immobilization Strategy for Diacetylchitobiose Deacetylase
by Guoyun Sun, Ziyang Huang, Zhiqian Zhang, Yanfeng Liu, Jianghua Li, Guocheng Du, Xueqin Lv and Long Liu
Catalysts 2022, 12(9), 932; https://doi.org/10.3390/catal12090932 - 23 Aug 2022
Cited by 4 | Viewed by 2370
Abstract
Free enzymes often face economic problems due to their non-recyclability, which limits their applications for industrial manufacturing. Organic biopolymers are frequently used to fabricate hydrogel for enzyme immobilization due to their advantages of non-toxicity, biocompatibility, biodegradability, and flexibility. However, for highly thermostable enzymes, [...] Read more.
Free enzymes often face economic problems due to their non-recyclability, which limits their applications for industrial manufacturing. Organic biopolymers are frequently used to fabricate hydrogel for enzyme immobilization due to their advantages of non-toxicity, biocompatibility, biodegradability, and flexibility. However, for highly thermostable enzymes, simple cross-linking causes either low immobilizing efficiency or low thermal stability. Herein, we developed a novel enzyme immobilization strategy with two-step cross-linked gelatin hydrogel for thermostable enzymes working at high temperature. The hydrogel was firstly “soft cross-linked” to immobilize most enzyme molecules and then “hard cross-linked” to gain strong thermal stability. We selected the enzyme diacetylchitobiose deacetylase (Dac), which was firstly derived from hyperthermophilic bacteria, to demonstrate the advantages of our method. With the optimized fabrication steps, our hydrogel showed ~87% Dac immobilization efficiency and excellent stability against heating, dehydrating, long-time storing, and massive recycling. Importantly, our hydrogel showed ~85.0% relative enzyme activity at 80 °C and retained ~65.8% activity after 10 rounds of catalysis. This strategy showed high immobilizing efficiency and strong thermal stability and we believe it could improve the industrial potential for those enzymes. Full article
(This article belongs to the Special Issue Recent Trends in Enzyme Immobilization)
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