Wandrey Christian
Institute of Biotechnology, Research Center Jülich, D-52425, Germany.
Chem Rec. 2004;4(4):254-65. doi: 10.1002/tcr.20016.
Redox reactions are still a challenge for biochemical engineers. A personal view for the development of this field is given. Cofactor regeneration was an obstacle for quite some time. The first technical breakthrough was achieved with the system formate/formate dehydrogenase for the regeneration of NADH2. In cases where the same enzyme could be used for chiral reduction as well as for cofactor regeneration, isopropanol as a hydrogen source proved to be beneficial. The coproduct (acetone) can be removed by pervaporation. Whole-cell reductions (often yeast reductions) can also be used. By proper biochemical reaction engineering, it is possible to apply these systems in a continuous way. By cloning a formate dehydrogenase and an oxidoreductase "designer bug" can be obtained where formate is used instead of glucose as the hydrogen source. Complex sequences of redox reactions can be established by pathway engineering with a focus on gene overexpression or with a focus on establishing non-natural pathways. The success of pathway engineering can be controlled by measuring cytosolic metabolite concentrations. The optimal exploitation of such systems calls for the integrated cooperation of classical and molecular biochemical engineering.
氧化还原反应对生化工程师来说仍然是一个挑战。本文给出了对该领域发展的个人观点。辅因子再生在相当长一段时间内都是一个障碍。首个技术突破是通过甲酸/甲酸脱氢酶系统实现了NADH2的再生。在同一酶可用于手性还原以及辅因子再生的情况下，异丙醇作为氢源被证明是有益的。副产物（丙酮）可通过渗透蒸发去除。全细胞还原（通常是酵母还原）也可使用。通过适当的生化反应工程，有可能以连续方式应用这些系统。通过克隆甲酸脱氢酶，可获得一种“设计菌”氧化还原酶，其中使用甲酸而非葡萄糖作为氢源。通过专注于基因过表达或专注于建立非天然途径的途径工程，可建立复杂的氧化还原反应序列。途径工程的成功可通过测量胞质代谢物浓度来控制。对这类系统的最佳利用需要经典生化工程与分子生化工程的综合协作。
