“…Although reports describing the reconstitution of P450BM3 with artificial cofactors (aluminium protoporphyrin IX, iron(III) deuteroporphyrin IX, and methyliridium deuteroporphyrin IX) do exist, there is a lack of P450BM3 crystal structures containing artificial cofactors, and, until recently, only the crystal structure of mutant P450BM3 with iron(III) deuteroporphyrin IX had been reported on the PDB (PDB ID: 5JQU and 5JQV) . Recently, our group reported the crystal structure of the P450BM3 haem domain incorporating manganese protoporphyrin IX (MnPPIX), at a mediocre resolution of 3.10 Å (PDB ID: 5ZIS), which, although sufficient to indicate the correct reconstitution of P450BM3 with MnPPIX, was insufficient to allow the discussion of structural perturbations of the side chains. To highlight the superiority of the batch‐microcrystallisation method using seeds of P450BM3–AbiATrp, we endeavoured to crystallise the P450BM3 haem domain after reconstitution with a selection of d‐block transition metals of the periods 4 (Cr, Mn, Co) and 5 (Mo, Ru, Rh).…”