http://news.sciencemag.org/biology/2014/05/designer-microbes-expand-lifes-genetic-alphabet
DNA 2.0. By adding a new base pair, X and Y, to DNA's A-T and G-C pairs, researchers will enable organisms to build proteins from as many as 172 different amino acids. [gulp]
…the newly expanded genetic code opens the door for synthetic biologists to create microbes capable of building their proteins out of as many as 172 different amino acids, both natural and artificial—a potential boon to drug and materials developers.
Cool find, thank you for sharing it!
How do they arrive at this figure of 172? Shouldn't it be 216? (6 cubed). Maybe subtract one for a stop signal to be picky about it.
The old way with 4 different bases and 3 bases per codon gives 4^3 or 64 combinations, yet only codes for 20 different amino acids and a few stop codons. Many amino acids have multiple codons.
See http://en.wikipedia.org/wiki/DNA_codon_table and http://en.wikipedia.org/wiki/Genetic_code#RNA_codon_table for details.
It looks like they just took the total number of combinations and subtracted 44 from it:
64-44=20. 216-44=172.
Are we waiting for a hostile takeover by super-microbes of our own creation, now…?
