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| In vitro Construction of the Threonine Cycle Pathway for Carbon Fixation |
| JU Xiao-zhi1,2, YUAN Qian-qian2,3, MA Chun-ling2, XIAO Dong-guang1, MA Hong-wu2 |
1. College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China;
2. Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China;
3. College of Chemical Engineering, Tianjin University, Tianjin 300072, China |
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Abstract Acetyl-CoA is a central metabolite and an important precursor for the synthesis of many valuable products. However, the carbon yield of acetyl-CoA is relatively low due to the carbon loss at the pyruvate decarboxylation step. Therefore, it was of great significance to construct an efficient pathway for acetyl-CoA synthesis. The attempts is to validate the high carbon molar yield reported in the literature to synthesize acetyl-CoA threonine carbonization pathway, which has important theoretical significance and application value.So, carbon fixation pathway via threonine cycle was used to synthesize acetyl CoA in vitro. When pyruvate was used as the substrate, serine deaminase (TdcB) was the last step of the cycling pathway in the in vitro characterization. The results showed that when all enzymes except serine deaminase were added to the reaction system, the measured acetyl CoA concentration was about 1.5 mmol/L at an nearly equilibrium state. After serine deaminase was added, serine to pyruvate and re-entry into the circulation, acetyl CoA concentration was increased 0.2 mmol/L. This result indicated that carbon fixation was achieved via the threonine cycle in vitro.
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Received: 10 January 2017
Published: 25 June 2017
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