How chirality affects the origins of life

Brett Smith for redOrbit.com – Your Universe Online

Life as we know it is based on essential building blocks like amino acids and sugars. How simple molecules ever started assembling into these life-giving structures has been a mystery for some time.

Now, a new study from joint team of American and Chinese researchers has revealed that natural forces are somewhat biased in favor of generating these structure from smaller molecules.

All molecules necessary for life generate structures that fall into two categories:  left-handed or right-handed. The terms “left-handed” or “right handed” refer to a structure’s chirality, or its asymmetry. Basically, if a structure is chiral – it does not look like its mirror image.

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Building life is not so mysterious

The generation of chiral structures, like amino acids or sugars, has been thought to be a highly complex process. However, the new study, published in the journal Nature Communications, has indicated that that process may be quite simple.

In the study, researchers learned that any molecules at least several nanometers in size tend to seek their own type to create larger assemblies in the presence of an electric charge.

“We show that homochirality, or the manner in which molecules select other like molecules to form larger assemblies, may not be as mysterious as we imagined,” said study author Tianbo Liu, a professor of polymer science at the University of Akron.

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The study team noted that we still don’t know how homochirality took place at the onset of life on Earth.

Another study on chirality published last year revealed how researchers were able to control chirality in reactions involving UV light, similar to the reactions involved in photosynthesis.

In order to control chirality, the researchers used catalyst to hold and orient chemicals under transformation via UV light in the correct orientation. According to study author Tehshik Yoon, from the University of Wisconsin-Madison, “if you make a really small tweak to the chiral control catalyst, you get a completely different shape to the product molecules.”

Yoon emphasized that the team had to use two catalysts in their process, with the second one controlling chirality.

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“One reason this field has failed is that a single catalyst had to both absorb light and control the chirality,” Yoon said. “If you tweak the single catalyst, you change its effects. By separating the two roles, you can make all kind of changes to chirality without messing up the photochemical catalyst. To get this to work, two stars have to be aligned.”

Incidentally, controlling chirality is of extreme interest to the pharmaceutical industry for the creation of new drugs.

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Source: http://www.redorbit.com/news/science/1113351938/how-chirality-affects-the-origins-of-life-031315/