Enzyme Immobilization on Graphite Oxide (GO) Surface via One-Pot Synthesis of GO/Metal-Organic Framework Composites for Large-Substrate Biocatalysis
| Autor: | Qiaobin Li, Zhongyu Yang, Yanxiong Pan, Yongki Choi, Isabelle Schuster, Jasmin Farmakes, Amanda Overby, Angel Ugrinov, Mary Lenertz, Lina Alhalhooly |
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| Rok vydání: | 2020 |
| Předmět: |
Materials science
Immobilized enzyme One-pot synthesis Graphite oxide 02 engineering and technology 010402 general chemistry 01 natural sciences Catalysis Micrococcus chemistry.chemical_compound Protein Domains Cell Wall General Materials Science Composite material Metal-Organic Frameworks Substrate (chemistry) Hydrogen-Ion Concentration 021001 nanoscience & nanotechnology Enzymes Immobilized 0104 chemical sciences chemistry Biocatalysis Metal-organic framework Graphite Muramidase 0210 nano-technology Zeolitic imidazolate framework |
| Zdroj: | ACS applied materialsinterfaces. 12(20) |
| ISSN: | 1944-8252 |
| Popis: | Although enzyme immobilization has improved many areas, biocatalysis involving large-size substrates is still challenging for immobilization platform design because of the protein damage under the often "harsh" reaction conditions required for these reactions. Our recent efforts indicate the potential of using Metal-Organic Frameworks (MOFs) to partially confine enzymes on the surface of MOF-based composites while offering sufficient substrate contact. Still, improvements are required to expand the feasible pH range and the efficiency of contacting substrates. In this contribution, we discovered that Zeolitic Imidazolate Framework (ZIF) and a new calcium-carboxylate based MOF (CaBDC) can both be coprecipitated with a model large-substrate enzyme, lysozyme (lys), to anchor the enzyme on the surface of graphite oxide (GO). We observed lys activity against its native substrate, bacterial cell walls, indicating lys was confined on composite surface. Remarkably, lys@GO/CaBDC displayed a stronger catalytic efficiency at pH 6.2 as compared to pH 7.4, indicating CaBDC is a good candidate for biocatalysis under acidic conditions as compared to ZIFs which disassemble under pH < 7. Furthermore, to understand the regions of lys being exposed to the reaction medium, we carried out a site-directed spin labeling (SDSL) electron paramagnetic resonance (EPR) spectroscopy study. Our data showed a preferential orientation of lys in GO/ZIF composite, whereas a random orientation in GO/CaBDC. This is the first report on immobilizing solution-state large-substrate enzymes on GO surface using two different MOFs via one-pot synthesis. These platforms can be generalized to other large-substrate enzymes to carry out catalysis under the optimal buffer/pH conditions. The orientation of enzyme at the molecular level on composite surfaces is critical for guiding the rational design of new composites. |
| Databáze: | OpenAIRE |
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