Institute of Biochemistry, Department of Biotechnology and Enzyme Catalysis, University of Greifswald, Felix-Hausdorff-Straße 4, 17487, Greifswald, Germany.
Leibniz Institute for Catalysis e.V., Albert-Einstein-Straße 29a, 18059, Rostock, Germany.
Angew Chem Int Ed Engl. 2024 Apr 15;63(16):e202319313. doi: 10.1002/anie.202319313. Epub 2024 Feb 26.
Novel concepts to utilize carbon dioxide are required to reach a circular carbon economy and minimize environmental issues. To achieve these goals, photo-, electro-, thermal-, and biocatalysis are key tools to realize this, preferentially in aqueous solutions. Nevertheless, catalytic systems that operate efficiently in water are scarce. Here, we present a general strategy for the identification of enzymes suitable for CO reduction based on structural analysis for potential carbon dioxide binding sites and subsequent mutations. We discovered that the phenolic acid decarboxylase from Bacillus subtilis (BsPAD) promotes the aqueous photocatalytic CO reduction selectively to carbon monoxide in the presence of a ruthenium photosensitizer and sodium ascorbate. With engineered variants of BsPAD, TONs of up to 978 and selectivities of up to 93 % (favoring the desired CO over H generation) were achieved. Mutating the active site region of BsPAD further improved turnover numbers for CO generation. This also revealed that electron transfer is rate-limiting and occurs via multistep tunneling. The generality of this approach was proven by using eight other enzymes, all showing the desired activity underlining that a range of proteins is capable of photocatalytic CO reduction.
需要利用二氧化碳的新概念来实现循环碳经济并最小化环境问题。为此，光、电、热和生物催化是实现这一目标的关键工具，优选在水溶液中进行。然而，能够在水中高效运行的催化体系仍然稀缺。在这里，我们提出了一种基于潜在二氧化碳结合位点的结构分析和随后的突变来识别适合 CO 还原的酶的通用策略。我们发现，枯草芽孢杆菌（BsPAD）中的酚酸脱羧酶在钌敏化剂和抗坏血酸钠的存在下促进水相光催化 CO 还原，选择性地生成一氧化碳。通过对 BsPAD 的工程化变体进行突变，TON 高达 978，选择性高达 93%（有利于所需的 CO 生成而不是 H 生成）。突变 BsPAD 的活性位点区域进一步提高了 CO 生成的周转数。这也表明电子转移是限速步骤，并且通过多步隧穿发生。该方法的通用性通过使用其他八种酶得到了证明，所有这些酶在证明了一系列蛋白质能够进行光催化 CO 还原的情况下都表现出了所需的活性。
