Modern cell-free in vitro protein synthesis systems present powerful tools for the synthesis of isotope-labeled proteins in high yields. The production of selectively ¹⁵ N-labeled proteins from ¹⁵ N-labeled amino acids is particularly economic and yields are often sufficient to analyze the proteins very quickly by two-dimensional NMR spectra recorded of the crude reaction mixture without concentration or chromatographic purification of the protein. We review methodological aspects of cell-free in vitro protein synthesis based on an Escherichia coli cell extract, in particular with regard to the production of ¹⁵ N-labeled proteins for analysis by NMR spectroscopy.

IUBMB Life, 57: 615-622, 2005