Life as we know it originated roughly 3.5 to 4 billion years ago in the form of a prebiotic soup of organic molecules that somehow began to replicate themselves and pass along a genetic formula--or so goes the thinking behind the RNA World, one of the most robust hypotheses on the origin of life. Researchers at the University of California-Santa Barbara (UCSB) have now found evidence that the amino acid arginine (or its prebiotic world equivalent) may have been a more important ingredient in this soup than previously thought. "People tend to think of arginine as not being prebiotic," said Irene Chen, MD, PhD, a biophysicist whose research focuses on the chemical origins of life. "They tend to think of the simpler amino acids as being plausible, such as glycine and alanine." Arginine, by contrast, is relatively more complex, and was therefore thought to have entered the game at a later stage. Primordial Earth, according to the RNA World theory, had the conditions to host several types of biomolecules, including nucleic acids (which become genetic material), amino acids (which eventually link to form the proteins that are responsible for structure and function of cells), and lipids (which store energy and protect cells). Under what circumstances and how these biomolecules worked together is a source of ongoing investigation for researchers of the origins of life. For their investigation, the UCSB scientists analyzed a dataset of in vitro evolved complexes of proteins and aptamers (short RNA and DNA molecules that bind to specific target proteins).
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