SoylentNews

NotSanguine [soylentnews.org] writes:

Science Daily is reporting [sciencedaily.com] on new research [aps.org] [abstract;full paper paywalled] by researchers at the University of Illinois at Urbana-Champaign. The researchers, Swanlund Professor of Physics Nigel Goldenfeld, graduate student Farshid Jafarpour, and postdoctoral researcher Tommaso Biancalani have made a breakthrough in one of the most central chemical quirks of life as we know it: homochirality, the uniform "handedness" of biological molecules.

From the artcle:

Life is quirky. Although the molecules that make up all living things obey physical and chemical laws, they do so with a puzzling twist. How did the distinctive molecular features of life emerge, and what can they tell us about life on Earth and elsewhere in the universe?

...

Many chemicals, organic or otherwise, are chiral; that is, if the structure of each was reflected in a mirror, its "looking-glass" copy could not be turned or flipped to match the original. Like a pair of gloves, the left-handed and right-handed versions of a chiral molecule are functionally equivalent, but their fundamental asymmetry makes them distinct.

Inorganic reactions produce and consume both versions of chiral molecules at equal rates. This is what makes the chirality of biological molecules, such as sugars produced by microbes and plants or the amino acids that make up proteins, so shocking. In every living thing on Earth, all amino acids are left-handed, and all sugars are right-handed. Goldenfeld highlighted the central mystery of this phenomenon.

"Imagine you've got a coin, and it's perfectly made, so it's not biased at all, and you start flipping the coin. Each time you flip it, it keeps coming up heads," he said. "So then you say, something must be operating that's causing this to happen . . . you get the same puzzle with these biological molecules, and that's the problem of homochirality."

...

"There are other models, and they may be correct for the origin of homochirality on earth, if you can prove that those prerequisites existed during the emergence of life," said Jafarpour. "But whether those foundations exist or not, for life that emerged anywhere in the universe, you'd expect that it would have self-replication, and our model says that's enough to get homochirality."

...

The work leads to a key conclusion: since homochirality depends only on the basic principles of life, it is expected to appear wherever life emerges, regardless of the surrounding conditions.

"For me, the most exciting thing is that this mechanism shows that homochirality is really a biosignature of life, a 100% signature, and should be expected anywhere life emerges," said Goldenfeld. "So for example, we just learned that there is a global ocean of liquid water under the ice of Enceladus ... I think that looking for homochirality in the organic molecules that have been detected there would be a fantastic way to look for life there."

Should this model be validated, it could be a big step forward in recognizing life in the universe -- even if it's not life "as we know it." Fascinating stuff!

Original Submission