Production of Proteins for NMR Studies Using the Wheat Germ Cell-Free System

This chapter describes protocols for preparing ¹⁵ N-labeled proteins (ubiquitin is used as an example) using Escherichia coli cells (with purification) and the wheat germ cell-free system (without purification). A comparison of ¹ H-¹⁵ N heteronuclear single-quantum coherence (HSQC) spectra of yeast ubiquitin prepared using each method indicates that this wheat germ cell-free system may be used for rapid nuclear magnetic resonance analyses of proteins without purification.