we would like to label the prolines and cysteines in a protein 13C. An
efficient expression system for the unlabeled protein is already
available in E. coli. We are now planning to exchange the E. coli by its
auxotrophic mutant to substitute the desired amino.
So we would like to know, how we could find the auxotrophic mutants of
E. coli and if our plan could work anyway?