The screening of potential affinity ligands and the development of a two-stage affinity purification of an S-adenosylmethionine-dependent 3-amino-3-carboxypropyl transferase involved in the biosynthesis of the β-lactam antibiotic nocardicin A is described from a cell- free extract of Nocardia uniformis subsp. tsuyamanesis. This protein is particularly sensitive to ion exchange and salt effects necessitating a pair of neutral ligands to be used in the ...