An economical method for producing stable-isotope labeled proteins by the E. coli cell-free system

作者：Yokoyama Jun; Matsuda Takayoshi; Koshiba Seizo; Kigawa Takanori^*

来源：Journal of Biomolecular NMR, 2010, 48(4): 193-201.

DOI：10.1007/s10858-010-9455-3

• Cell-free protein synthesis
• In vitro translation
• Stable-isotope labeling
• Metabolic conversion

Improvement of the cell-free protein synthesis system (CF) over the past decade have made it one of the most powerful protein production methods. The CF approach is especially useful for stable-isotope (SI) labeling of proteins for NMR analysis. However, it is less popular than expected, partly because the SI-labeled amino acids used for SI labeling by the CF are too expensive. In the present study, we developed a simple and inexpensive method for producing an SI-labeled protein using Escherichia coli cell extract-based CF. This method takes advantage of endogenous metabolic conversions to generate SI-labeled asparagine, glutamine, cysteine, and tryptophan, which are much more expensive than the other 16 kinds of SI-labeled amino acids, from inexpensive sources, such as SI-labeled algal amino acid mixture, SI-labeled indole, and sodium sulfide, during the CF reaction. As compared with the conventional method employing 20 kinds of SI-labeled amino acids, highly enriched uniform SI-labeling with similar labeling efficiency was achieved at a greatly reduced cost with the newly developed method. Therefore, our method solves the cost problem of the SI labeling of proteins using the CF.

• 出版日期2010-12