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Enhancing Robustness of Sortase A by Loop Engineering and Backbone Cyclization
Staphylococcus aureus sortase A (SaSrtA) is widely used for site-specific protein modifications, but it lacks the robustness for performing bioconjugation reactions at elevated temperatures or in presence of denaturing agents. Loop engineering and subsequent head-to-tail backbone cyclization of SaSrtA yielded the cyclized variant CyM6 that has a 7.5 °C increased melting temperature and up to 4.6-fold increased resistance towards denaturants when compared to the parent rM4. CyM6 gained up to 2.6-fold (vs. parent rM4) yield of conjugate in ligation of peptide and primary amine under denaturing conditions. © 2020 The Authors. Published by Wiley-VCH GmbH
One‐Pot Two‐Step Chemoenzymatic Cascade for the Synthesis of a Bis‐benzofuran Derivative
Chemoenzymatic cascades enable reactions with the high productivity of chemocatalysts and high selectivity of enzymes. Nevertheless, the combination of these different fields of catalysis is prone to mutual deactivation of metal- and biocatalysts. In this study, a one-pot sequential two-step catalytic cascade reaction was successfully implemented for the synthesis of a methylene-bridged bis(2-substituted benzofuran). In the first step, a palladium-free Sonogashira reaction is used for the synthesis of a benzofuran derivative. In the subsequent step, the formed 2-substituted benzofuran is hydroxylated by the monooxygenase P450 BM3 variant (A74S-F87V-L188Q) and undergoes further elimination reactions. The study proofs that combination of Cu scorpionate catalyzed Sonogashira cross-coupling and P450 mediated oxidation is possible and results in up to 84 % yield of the final product. The oxidation reaction is boosted by capturing inhibiting reaction components.