20 SEP 2026 — An enzyme taken from an archaeon living near deep-sea volcanic vents converts nitrogen gas into ammonia at temperatures that would cook most proteins. At room temperature it does nothing at all.
That second fact is the one worth sitting with. This is not a heat-tolerant version of a familiar enzyme; it requires the heat.
What was imaged
Researchers at the Max Planck Institute for Marine Microbiology in Bremen and the Institut de Biologie Structurale in Grenoble determined the structure of the nitrogenase from Methanocaldococcus infernus, an organism that grows in marine volcanic areas where vent fluids can exceed the boiling point of water.
The paper, "Molecular basis of N2 fixation in a hyperthermophilic archaeon" by Nevena Maslać and colleagues, appeared in Nature Communications. Phys.org reported it on 15 September.
The structures were obtained at near-atomic resolution. The enzyme they show is the most simplified nitrogenase described so far.
Where the heat comes in
The enzyme remains stable up to 90 degrees Celsius, and some of it survives at 98. Nitrogenase from organisms living at ordinary temperatures does not behave this way.
Tristan Wagner, a laboratory director at the Max Planck Institute, put the demand in domestic terms. The enzyme is built to work in conditions where most proteins would rapidly decay, like egg white cooked in hot water.
The temperature dependence runs the other way too. The enzyme produces ammonia only at elevated temperatures and is inactive at room temperature. Its stability and its activity are not separable properties.
Why nitrogen fixation is hard
Atmospheric nitrogen is two nitrogen atoms held by a triple bond, one of the strongest in chemistry. Industry breaks it with the Haber-Bosch process, which runs at high pressure and high temperature and accounts for a substantial share of global industrial energy use.
Nitrogenase does the same job at ambient pressure using a metal cofactor. The prospect of doing it more cheaply is why the enzyme has been studied for decades.
The version here is molybdenum-containing and was captured in a turnover state. The authors describe it as showing a mechanistic principle common to nitrogenases, not a quirk of this one.
The evolutionary argument
The structure combines traits of all three known nitrogenase forms. The authors take that as support for the proposal that ancestral nitrogenases resembled the archaeal enzyme more closely than they resembled the bacterial ones.
That is an argument from architecture rather than from dating, and it is offered as reinforcement of an existing proposal rather than as a settled result.
The authors are explicit that questions remain open. Precisely how the metal cofactors enable the triple bond to be cleaved is still an active area, and the relationships between the molybdenum, vanadium and iron forms need further work.
What this does not deliver
No industrial application follows from this. A thermostable enzyme is easier to work with than a fragile one, which helps in the laboratory. That is still some distance from a process.
The release also gives no activity comparison in numbers. The enzyme is described as having an extrapolated specific activity superior to its counterparts from organisms living at moderate temperatures, and extrapolated is doing work in that sentence.
What has been added is a structure of the simplest known member of an enzyme family that people have been trying to understand for fifty years. It came from an organism nobody would have thought to look at without the vents.
View author profile → · Editorial policy
