The Use of Cell-Free Protein Expression for NMR Analysis

Until recently, cell-free protein expression (also sometimes erroneously named in vitro protein expression) did not exhibit the productivity required for preparation of NMR samples, especially considering the high cost of using isotopically labeled starting material. Rather, it was exclusively used as an analytical tool that served to verify correct cloning or to study promotor sites. Because of the very low yields, detection of the expressed product usually required incorporation of a radioactive label (usually via 35S-methionine). 

Recently, a system for cell-free protein production has became commercially available (the Rapid Translation System, RTS) [157]. In the following sections this system will be described, and advantages as well as limitations will be discussed. 

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