An orthogonal purification strategy for isolating crosslinked domains of modular synthases

Chemo-enzymatic methods for covalently crosslinking carrier proteins with partner enzymes within modular synthases hold promise for elucidating and engineering metabolic pathways. Our efforts to crystallize the ACP–KS complexes of fatty acid synthases have been complicated by difficulties in the purification of the crosslinked complex from the other proteins in the reaction. Here we present a solution that employs an orthogonal purification strategy to achieve the quantity and level of purity necessary for further studies of this complex.