Protein labeling in Escherichia coli with (2)H, (13)C, and (15)N

A number of structural biology techniques such as nuclear magnetic resonance spectroscopy and small-angle neutron scattering can be performed with proteins with nuclei at natural isotope abundance. However, the use of proteins labeled with stable isotopes ((2)H, (13)C, and (15)N) enables greater experimental flexibility. In this chapter, several methods for uniform and fractional protein labeling with stable isotopes using Escherichia coli in a defined media are described. The methods described can be used for labeling with single or multiple isotopes.