Phosphorus for the first living cells could fly from space

File Global Look Press

UNITED STATES (VOP TODAY NEWS) – Scientists have long struggled with the question of where on the ancient Earth phosphorus in a form suitable for the emerging life came from. Now, researchers have found a mechanism by which the necessary substances could be formed directly in the protoplanetary disk.

The achievement is described in a scientific article published in Nature Communications magazine by a group led by Ralf Kaiser from the University of Hawaii at Manoa.

Phosphorus is one of the most important chemical elements for living organisms. It is part of the DNA that stores hereditary information, RNA, carries out protein synthesis and performs many other functions, ATP – the universal energy source for cells, phospholipids – the building material for cell membranes. The list goes on. Life as we know it is unthinkable without phosphorus.

However, in the inanimate nature of the Earth, this element occurs mainly in the form of poorly soluble in water and chemically inert phosphates. They are not suitable for the role of a source of phosphorus for the first living organisms. How then could life have arisen?

On this issue, scientists have been racking their brains for years. It has been proposed several possible sources of phosphorus in a convenient form for assimilation. The Kaiser team proposed a new intriguing option.

Scientists have reproduced in the laboratory the conditions of the protoplanetary disk, from which all the bodies of the solar system originated. To do this, they needed a deep vacuum, cooling the substance down to -268 ° C and an electron beam simulating cosmic rays.

The material served as grains of frozen carbon dioxide and water. In cold protoplanetary disks, these substances are very common. Also, the composition of these particles of matter included phosphine H 3 P. This simple connection was also certainly present in the protoplanetary cloud.

Scientists have discovered that oxygen-containing acids (oxo acids) based on phosphorus are formed under these conditions. Among them are phosphoric acid H 3 PO 4 , phosphonic acid H 3 PO 3 and pyrophosphoric acid H 4 P 2 O 7 . During the first billion years of the Earth’s existence, they could have been delivered to the planet by meteorites and comets. There, having entered into chemical reactions, they would form such forms of phosphorus that are soluble and suitable for life assimilation, such as phosphites HPO 3 2- and pyrophosphates P 2 O 7 4-.

“On phosphine deadly world of living beings, – explains the first author of the article, Andrew Turner ( Andrew Turner ), also from the University of Hawaii at Manoa -. But in the interstellar medium exotic chemistry of phosphine may contribute to the rare paths for chemical reactions and initiate the formation of biorelevant molecules such as phosphorus oxo acids, which could ultimately trigger the molecular evolution of life as we know it. ”

We note, however, that the option proposed by the authors to enrich the “prebiosphere” with phosphorus is by no means the only one. We briefly describe some other scenarios. You can read more about them in Mikhail Nikitin’s remarkable book, The Origin of Life: From Nebula to Cell.

For example, some meteorites contain iron phosphide Fe 3 P. When released into the water, this substance gradually decomposes, with up to 50% of phosphorus being converted to phosphites and up to 5% to pyrophosphates.

Another source of this important element could have been volcanoes. The gases of some “fire-breathing mountains” contain a noticeable amount of phosphorus oxides P 4 O 10 , PO 2 and P 4 O 6 . When dissolved in water, phosphites and pyrophosphates are also formed. Phosphites are also found in the water of some geothermal sources and volcanic mud pots (namely, according to many experts, life originated there).

It is unlikely that we will ever know what mechanism or mechanisms actually worked on the young Earth. But the more realistic options offered by experts, the more the emergence of life turns from darkness-covered secrets into a process that is studied and accessible to an understanding.