A deadly poison, arsenic is best known for snuffing out life. But could it have played a key role in the origins of life on Earth?
Felisa Wolfe-Simon of Harvard University thinks so because the toxin behaves so similarly to phosphorus, an essential ingredient in nearly all living things. Much more arsenic would have been available in Earth's primordial oceans than phosphorus. And while microbial activity was necessary later to unlock phosphorus from rocks, arsenic could have dissolved in water from hydrothermal vents.
"If you put arsenic in a test tube with adenosine, you immediately get lots of adenosine monoarsenate," which is structurally similar to adenine, the "A" letter in DNA's code of A, C, G and T, says Wolfe-Simon.
If early life did use arsenate, single-celled organisms with arsenate-based DNA may still be around today wherever phosphorus is scarce.
clipped from: www.newscientist.com