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August 14, 2022

Miller’s pre-biotic soup was missing sulfur

By Mali Wiederkehr | April 7, 2011

Researchers recently revisited Stanley Miller’s work and discovered that hydrogen sulfide released from volcanoes contributed to the formation of some of the most primitive amino acids on earth.

Stanley Miller (1930-2007) is notorious for his contribution to chemistry through his work on the primordial earth.

Miller is largely responsible for the discovery that amino acids can be synthesized from simple chemicals present on Earth before life emerged.

Miller’s experiments in the ‘50s showed that when electricity zaps basic chemicals such as water, hydrogen, methane and ammonia, these chemicals combine to form amino acids (molecules that are the building blocks of proteins).

The electricity used in Miller’s experiments stands in for lightning, which is believed to have generated amino acids in the primitive earth.

Recent work on some of Miller’s forgotten vials shows the presence of more amino acids than Miller had initially anticipated.

Eric Parker, a graduate student at Georgia Tech, and his team found 23 amino acids, seven other compounds and four amines, whereas the initial analysis of the samples showed the presence of only 10 amino acids.

“When you are analyzing old samples, you always hope in the back of your mind that you are going to find something really cool,” Parker told Wired Science, “It was a pleasant surprise to see such a large array of different amino acids and amines.”

Among the newly discovered amino acids, Parker’s team found methionine, which is a crucial building block in animals, plants and fungi.

Another observation about Parker’s amino acids is that they are common to the amino acids found in meteorites, implying that sulfur is a key ingredient on other planets as well.

Miller had initially concluded that the “primordial soup” had atmospheric origins, but Parker’s work on Miller’s experiment suggest that volcanoes played a role in amino acid synthesis by donating sulfur and other chemicals.

“Miller was a real packrat. He didn’t throw anything out,” Jim Cleaves, a geochemist at the Carnegie Institution of Washington, Miller’s final lab student and inheritor of the lab, told Wired Science. “Sitting on the shelf was this box, I thought, ‘I don’t know what these are, but I can’t bear to throw them out!’”

Luckily, Cleaves decision to keep Miller’s materials has led to further developments in this field, which further elucidates the mystery of Earth’s beginnings.

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