The chemical reaction that was life's starting point over four billion years ago
Life began with a chemical reaction under the sea over four billion years ago. That is the claim of German scientist Gunter Wachtershauser, whose team has recreated a crucial part of the reaction, synthesising all the necessary ingredients for a living organism. All that was needed was volcanic gases, water and rock.
Researchers at the University of Munich, Germany, synthesised hydroxyl acids and amino acids - life’s first enzymes and the ingredients for further reactions between organic molecules, and the eventual development of living organisms.
They used cyanide and carbon monoxide, volcanic gas chemicals, and iron and nickel transition metal catalysts, which are found in the rock of the sea bed. According to Wachtershauser the study has solved one of the remaining mysteries shrouding the origin of life chemistry.
’Until now the presence of amino acids was relegated to their existence in a prebiotic broth of organic material,’ he said. ’We have now synthesised a mixture of everything that life needs at one site under realistic chemical conditions.’
Wachtershauser told Chemistry World that life originated from a positive feedback loop of chemical reactions where the products of reactions went on to react further, eventually building an evolving organism. ’Amino acids are ligands for transition metals, meaning that they form reactive complexes with these metals,’ he explained. ’As chemical reactions formed more of these ligands, an autocatalytic feedback system eventually developed.’
As the mixture of cyanide and carbon monoxide is exhaled from the volcano into the sea, it cools rapidly, providing the chemical conditions for these biological ingredients to react.
’This cooling is known as quenching and it essentially freezes the mixture, which means that it comes out of equilibrium,’ said Wachtershauser. ’This "frozen" mixture has huge chemical potential and reacts when it comes into contact with catalytic metals in the rock.’
Michael Adams, a biochemist from the University of Georgia, US, has followed Wachtershauser’s work closely. ’This is very exciting because it is such clean chemistry,’ Adams told Chemistry World. ’It produces a good yield of these substances and we know that life can exist at these temperatures. This has narrowed the gap between biochemistry and volcanic geochemistry, which has created problems for the field.’
Wachtershauser believes that he has laid the foundations to go on to produce the autocatalytic feedback system to show how life began. His ultimate goal is the production of a ’pioneer organism’ which, in theory, would allow researchers to sit back and observe evolution from its very earliest point.
’We’re a long way from that,’ cautioned Adams. ’But the pieces are slowly starting to come together and this study is a giant step forward for origin of life chemistry.’
The volcanic gas carbonyl sulfide (COS) might have triggered a key step in the origin of life by chemically activating amino acids.
Novel chiral amplification with links to origin of life
C Huber and G Wachtershauser, Science, 2006, 314, 630