Xpression by 400 mM isopropyl-b-D-1-thiogalactopyranoside. The temperature was adjusted to 20 , and bacteria were grown for a further 6 h. Bacterial cells were recovered by centrifugation at 5,000g and frozen as pellets. His-tagged TricSAM was purified by standard immobilized metal-affinity chromatography (GE Healthcare), with the protein recovered by elution with 200 mM imidazole. The elution sam