COLUMBUS, Ohio (AP) - Ohio State University researchers say they have discovered a 22nd common amino acid, another step in the scientific community's effort to unlock secrets of the genetic code.
It was the first time since 1986 that an amino acid was discovered. Before that, scientists had thought for nearly a century that only 20 gene-encoded amino acids existed.
DNA uses amino acids as the building blocks of protein in all living things, instructing organisms how to perform tasks. The new amino acid, called pyrrolysine, means DNA has decided there is another task to perform.
"That means that organisms can have the special function they need. The code in the DNA can really change and take on new tasks that we haven't seen before," OSU researcher Joseph Krzycki said Friday.
"This is the most basic level the genetic code works on. ... It just serves right now to show us how plastic evolution is."
The OSU researchers, made up of two teams of biochemists and microbiologists, reported their discovery Wednesday in the journal Science.
"I think it's a once in a lifetime experience," said OSU researcher Michael Chan. "There were only 21 and now they're 22. The chances of finding another one is going to be a real long shot."
John Atkins, a research professor in the department of human genetics at the University of Utah, said the Ohio State research empowers efforts by scientists who are looking for ways to make proteins with different amino acids.
"The significance is not so much there's a new amino acid, but rather what it shows about the versatility of the genetic code," Atkins said.
In 1995, Ohio State started research into what appeared to be abnormalities in the production of a certain protein by a known amino acid called lysine.
By 2000, the researchers had discovered that the protein was unique and had a special function: help microbes called methanogens convert material into methane, the organisms' energy source.
"The amino acid is a key piece in being able to do that," Chan said.
The amino acid is found in bacteria and some single-celled organisms but likely won't be found in humans, Chan said.
But Krzycki said the amino acid could still turn up in other living things.
"Nature doesn't waste chemistry," he said. "Once we've found that it's doing something fundamental that can do different things, it won't waste that. We'll probably see it in other places."
(Copyright 2002 by The Associated Press. All Rights Reserved.)