Scientists have investigated how ancient enzymes worked 3.2 billion years ago, when the Earth’s atmosphere was not yet saturated with oxygen. They believe that understanding the biochemical processes of nitrogen release using the enzyme nitrogenase is of great importance for the search for life in the Universe.
A world without oxygen
Nature Communications has published a study on the workings of the enzyme nitrogenase and its biochemical traces. At first glance, this research may seem far removed from space, but it could be of great importance in the search for life beyond Earth.
It is unlikely that scientists will be able to personally fly to other planets and search for plants and animals there in the coming decades. Most likely, the presence of life somewhere near another star will be discovered by studying the spectrum of light passing through the atmosphere of a planet in its orbit. This will involve searching for certain substances that clearly indicate the presence of life there. These are called biomarkers.
Oxygen is also frequently mentioned among biomarkers. Ultimately, all of the most energy-intensive biochemical processes on Earth are tied to it. However, for several years now, there has been debate about whether it can truly be considered the source of life.
Nitrogen
Much of the controversy surrounding oxygen as a biomarker is related to the fact that there are many abiotic processes that can produce it. However, an equally important point is that life can exist without it. For most of Earth’s history, there was very little oxygen in the atmosphere, and organisms simply did not use photosynthesis or respiration.
But where did they get their energy from? From reactions that were less efficient in terms of energy output. One of these was the release of nitrogen. This mechanism is extremely important today, but now as part of other biochemical cycles; back then, it was one of the main sources of energy.
The only problem is that the key element in this process is the nitrogenase enzyme. And it is not very visible on spectrograms. However, the characteristic ratio of nitrogen isotopes is easily detected there.
However, this raises a new problem. All of this is true for modern nitrogenase. But its analogues, which existed billions of years ago, could have consisted of completely different nucleotides and produced a completely different isotope distribution. It is precisely this question that is the subject of the new study.
The authors of the study showed that ancient nitrogenases differed greatly from modern ones. But the isotopic composition of the product of their activity was the same. This means that it can be used as a reliable biomarker, as far as any biomarker can be considered reliable.
According to phys.org
