How difficult/expensive is sample preparation for NMR?
A. Expression in E. coli is usually straightforward, and requires minimal media made with isotope-labeled sources of carbon and nitrogen (typically glucose and ammonium salts). In vitro folding may be required if the protein accumulates in inclusion bodies. Assuming a yield of 10 mg of purified and folded protein per liter of media, the cost of one NMR sample is around a few thousand $. A recipe for labeled minimal media can be found here.
