http://www.newscientist.com/article/mg20627601.300-did-exploding-stars-shatter-lifes-mirror.html?page=3
Did exploding stars shatter life's mirror?
- 19 May 2010 by Marcus Chown
- Magazine issue 2760. Subscribe and save
- For similar stories, visit the Astrobiology and Quantum World Topic Guides
"The property of handedness, known to chemists as chirality, is a feature of many molecules whose arrangement of atoms is not completely symmetrical. A chiral molecule comes in two forms that are rather like a pair of gloves. Right and left-handed gloves are essentially identical, with the same basic components, four fingers and a thumb, and the same function of keeping our hands snug and protected. They are not exactly the same, however: you cannot rotate or flip a glove of one type so that it will superimpose perfectly on the other. But look in a mirror, and a left-handed glove becomes right-handed.
Similar molecular mirror-image forms are called enantiomers. They are made from the same atoms and have the same chemical and physical properties. Most chemical reactions produce equal quantities of both.
That makes nature's predilection for one form - its "homochirality" - all the more strange. Only left-handed or "l" amino acids make up the proteins that provide our cells with structure and regulate their functions, and only right-handed or "d" sugars play an active part in biochemistry. It is like keeping a drawer full of only one sort of glove, while stubbornly refusing to wear the other."
