Life spawns from left-handed molecules

WEST LAFAYETTE, Ind., Aug. 5 (UPI) -- Chemists at Purdue University have discovered the first building blocks of life were all left-handed -- and remain that way today.

The findings may shed light on the earliest days of evolutionary history, says R. Graham Cooks, who with a team of chemists reported experiments suggesting why all 20 of the amino acids that comprise living things exhibit "left-handed chirality." That refers to the way basic biological molecules stack together in a left-handed way.

Amino acids can be oriented either left or right and still have the same chemical properties. But in living things, they all go to the left -- a puzzle to biologists for many years.

Now there may be an answer. A single amino acid called serine set the standard eons ago, forcing all other biological molecules to follow suit.

"We believe that serine was the first biological molecule to make a chiral choice, possibly one of the root steps in chemical evolution itself," said Cooks.