2024-04-13 05:46 来源：得道网
研究人员可能已经弄清楚了细胞产生能量所需的一种关键成分是如何在深空形成的。
研究人员在3月15日的《科学进展》杂志上报告说，计算和实验室实验表明，甘油酸可以从星际云中的二氧化碳和乙二醇的辐射爆炸中产生。
这项研究是“了解这些分子是如何在太空中形成的一个很好的开始，”安东尼·雷米扬(Anthony Remijan)说，他是弗吉尼亚州夏洛茨维尔国家射电天文台的天体化学家，没有参与这项研究。他说，这一发现表明，“如果你把正确的混合物放在一起，在合适的条件下，也许你甚至可以在太空中负担得起更复杂的分子。”
Glyceric acid plays an important role in cell textareabolism, energy balance and photosynthesis, and it can go on to help form other complex molecules important for life. The acidic sugar has previously been found in meteorites, suggesting that it can form in outer space. Astronomers have yet to directly observe glyceric acid in space, but they suspect it may form in interstellar clouds such as the Orion Nebula, which roils with gas, plasma and dust.
Telescope observations alone can’t decipher how an organic compound forms in space. But astronomers can identify what gases are present in interstellar clouds. And chemists can predict what happens to those gases when blasted with radiation. That approach has led scientists to demonstrate how, for example, the simple sugar ribose could be made in simulated interstellar conditions (SN: 4/7/16).
So the new study began with a principal question: “Can we synthesize [glyceric acid] at low temperature and low pressure, like we get in space?” says Ryan Fortenberry, a theoretical astrochemist at the University of Mississippi near Oxford. “We think we can.”
Fortenberry and colleagues started by looking into the properties of two compounds that are abundant in interstellar clouds — carbon dioxide and ethylene glycol, commonly known as the active ingredient in antifreeze.
Computer calculations of how CO₂ and ethylene glycol respond to radiation suggest that they could team up to form glyceric acid in space. To verify the theoretical results, physical chemist Ralf Ingo Kaiser of the University of Hawaii at Manoa and colleagues deposited ices of carbon dioxide and ethylene glycol in a vacuum chamber at extremely low pressure and temperature. The team then blasted the compounds with radiation.
“We cannot generate galactic cosmic rays in our lab,” Kaiser says, so they opted for the next best thing: spraying the compounds with electrons to simulate the shower of charged particles that’s triggered when cosmic rays hit ice. As the ices transitioned to vapors, the team further blasted the chamber with ultraviolet radiation, which resulted in the formation of glyceric acid molecules.
“It’s not magic,” Fortenberry says. “But it feels like magic, because you get these biologically significant species from really mind-blowingly simple molecules.”
While simple organic molecules are easy to observe in many cosmic environments, complex organics are harder to find. The study provides an understanding into “how much that very simple chemistry that we can observe can evolve into something more complex,” says Stefanie Milam, an astrochemist at NASA’s Goddard Space Flight Center in Greenbelt, Md.
A next step, Fortenberry’s team says, is to search interstellar clouds for glyceric acid. Astronomers could use the Atacama Large Millimeter/submillimeter Array in Chile, which has helped find phosphorus-bearing molecules and others important for life in the cosmos (SN: 1/21/20).
