... [15N]aminoacid(attheconcentration given above), 1 mMeach of 19 unlabelledL-amino ac ids, 1 5 mMmagnesium acetate, 175 lgÆmL)1E. coli total t RNA, 0.05% (w/v) N aN3,168lLofconcentrated S30 extract (containing ... systems based on Escheri chia coli extracts[2,10,15,16]. At these yields, protein concentrations aresufficiently high t o allow the recording of NMR spectrawithout further concentration of the reaction ... carlsbergensis, no data available forE. coli; bvalue for Lupinus luteus and bovine, no data availablefor E. coli; cvalue for Paracoccus denitrificans, no data availablefor E. coli. dvalue for Bacillus...