The proteins used by all of organic life on earth are composed of only twenty-two amino acids, which are thus referred to as the "natural" amino acids. Yet there are about five hundred other, different amino acids that already exist and can be synthesized, and these "unnatural" amino acids can now be incorporated into proteins by genetic engineering and the creation of novel tRNAs. These unnatural amino acids can be used to tag proteins for purification, localization and study; or they can be used to add new functional groups to existing proteins to make pharmacologically or otherwise useful new proteins. Researchers interested in evolution can plan experiments with unnatural amino acids to probe questions regarding the development and fitness of the modern genetic code.
The burgeoning field of synthetic biology can be used to create truly new life forms for all sorts of purposes. Engineered bacteria are being posited to churn out drugs and other commercially valuable molecules, to reseed and rehabilitate an ailing microbiome, and to help clean up our planet by providing energy or eliminating waste. But there is a concern that synthetic life can interact with natural organic life in unforeseen ways. Altering the genetic code of synthetic life forms to render them dependent on unnatural amino acids is a neat way to control their growth, limit them to a particular environment, and ensure that they are unable to combine with natural stocks.
Biosynth offers a range of roughly 450 unnatural amino acids. Among them are:
(S)-2-Amino-3-(4-hydroxy-phenyl)-propionic acid methyl ester or Methyl L-tyrosinate
(S)-2-(Boc-amino)-3-methylbutyric acid; (S)-2-(Boc-amino)pentanoic acid
Example application: As a complete component of a product molecule, Valine can increase the yield of Penicillin-developing cultures.
Fmoc-L-glutamic acid-Gamma-methyl ester
Example application: Alzheimer's and Parkinson research.