Fig. 4: Characterisation of Fe–S cluster as efficient Lewis acid.
From: Iron-sulphur protein catalysed [4+2] cycloadditions in natural product biosynthesis
a 1 μM 4 was incubated with 50 μM of apo-spinach Fd mutant, apo-MirFd mutant, reduced spinach Fd with [2Fe–2S](Cys)43− cluster, and reduced MirFd with [3Fe–4S](Cys)33− cluster, respectively. Fds were reduced with 1 mM sodium dithionite. b 1 μM 4 was incubated with 1 mM FeCl3, 1 mM FeSO4, 1 mM GaCl3, 1 mM desferrioxamine (DFO), and 1 mM DFO with 1 mM FeCl3. The in vitro reactions were conducted at 30 °C in 50 mM Tris-HCl (pH 7.5) for 30 min. c The crystal structure of the gallium-substituted Synechocystis sp. PCC 6803 Fd (SynFd), GaFd (PDB 5AUK). In vitro conversion of 1 μM 6 into 1 in 15 min (d) and 1 μM 4 into 5 in 30 min (e) in the presence of 200 μM SynFd and GaFd, respectively.
