Suppressor selectrion for amino acid replacements expected on the basis of the genetic code.

@article{Berger1967SuppressorSF,
  title={Suppressor selectrion for amino acid replacements expected on the basis of the genetic code.},
  author={H G Berger and C. Yanofsky},
  journal={Science},
  year={1967},
  volume={156 3773},
  pages={394-7}
}
In studies with A protein mutants of the tryptophan synthetase of Escherichia coli, missense supressors have been used to select for codon changes and corresponding amino acid replacements that are normally unobservable. The technique has permitted the detection of additional amino acid replacements expected on the basis of the genetic code.