Post

Amazing paper by Crick et al., in which they postulate that there are 20 common amino acids because the maximum size of a "comma-free code" on triples of ACTG is 20. I get to cite it because it turns out these codes give rise to optimal sampling (minimizer) schemes :D www.pnas.org/doi/10.1073/...

In short, a comma-free code is a set of words of length 3 in this case, such that the concatenation of any two such words contains no other chosen word as a non-trivial substring. I.e.: for any pair of code words ABC and XYZ, neither BCX nor CYX is allowed to be a code word.

CXY* rather. This property is nice: it basically means that you can start reading anywhere in the middle of a DNA string, and you'll be "synchronized" to the intended reading frame after the first 6 bases. And so the maximum size of a set of words that can satisfy this property turns out to be 20!

Yet frameshift exists and is a important for compact organisms (+ there is no 1 to 1 correspondence between cordons and AAs), so do they argue that this was a necessary condition at the origin of life, that was gradually lifted later?