Ohio State University scientists have discovered a new amino acid, which they have dubbed pyrrolysine.
Amino acids are the building blocks of proteins, which are essential components of the human body and other living things. Pyrrolysine is the 22nd amino acid to be discovered.
The amino acid is a component of an enzyme found in bacteria and bacteria-like organisms that helps them make methane, a gas found throughout nature.
The story of the discovery of pyrrolysine begins when one of the study authors who sequenced the methane-producing enzyme, and found it contained instructions that normally tell the protein-making cellular machinery to stop making amino acids. However, in this enzyme, the machinery did not stop.
This suggested that the "stop" instructions might, instead, code for a new amino acid. So investigators produced a highly detailed image of the protein, and found that it contained an amino acid different from 20 others more commonly found in nature.
In 1986, researchers had discovered a rarer, 21st amino acid.
Science May 24, 2002;296:1459-1465
This may not seem like a big break through, but amino acids are one of the foundational nutritional building blocks and with respect to nutritional biochemistry this is a major discovery.
It doesn't have any immediate practical applications though other than to illustrate that the obvious, that just when you think you know all the hard "facts" you really don't.