Selective backbone labeling of proteins using 1,2-13C2-pyruvate as carbon source.

A simple isotope labeling approach for selective (13)C/(15)N backbone labeling of proteins is described. Using {1,2-(13)C(2)}-pyruvate as the sole carbon source in bacterial growth media, selective incorporation of (13)C(alpha)-(13)CO spin-pairs into the backbones of protein molecules with medium-to-high levels of (13)C-enrichment is possible for a subset of 12 amino acids. The isotope labeling scheme has been tested on a pair of proteins--a 7-kDa immunoglobulin binding domain B1 of streptococcal protein G and an 82-kDa enzyme malate synthase G. A number of protein NMR applications are expected to benefit from the {1,2-(13)C(2)}-pyruvate based protein production.