Mitochondria May Use Quantum Physics to Boost ATP Production

Every cell in the body relies on minute power stations to keep functioning.

Mitochondria convert energy from food into ATP, the molecule that fuels almost everything a cell does. Exactly how they manage this so efficiently is still uncertain.

Researchers in China now suggest that quantum physics could provide part of the explanation.

A 71-terahertz mitochondrial signal

Across experiments with living cells, mouse tissue and isolated mitochondria, the researchers identified an unusual vibration that was present only when mitochondrial structures were left intact.

Their model connected this vibration with a potential quantum interaction. When cells were exposed to particular infrared frequencies, ATP output rose by 10 percent.

Taken together, these findings indicate that mitochondria could host a quantum state that affects cellular energy generation.

The study has been uploaded to bioRxiv as a preprint, so it has not yet undergone peer review.

Bo Song, from the School of Optical-Electrical and Computer Engineering at the University of Shanghai for Science and Technology, and his colleagues examined a human cell line as well as tissue from mouse kidneys, livers, hearts and skeletal muscles.

They applied Fourier-transform infrared spectroscopy, which reveals the response of samples to varying infrared-light frequencies.

Molecules and physical structures each vibrate at distinctive frequencies, rather like radio stations broadcasting on different channels. These frequencies can reveal clues about events occurring inside a sample.

The team identified an unusual 71-terahertz signal, oscillating 71 trillion times each second.

It was detected in living cells, mouse tissue and isolated mitochondria. Yet it vanished when samples were dried and ground up, a process that destroyed their organised structures.

"Mitochondrial quantum state provides a good way to explain the unknown frequency," Song told ScienceAlert.

However, this explanation is a hypothesis rather than direct evidence.

How cristae could create a quantum state

The researchers next examined cristae: the densely folded inner mitochondrial membranes. These folds contain abundant lipids with carbon-hydrogen, or CH2, bonds, which naturally vibrate at roughly 87 terahertz.

What, then, makes this quantum?

The team is not suggesting a mysterious new energy source. Instead, its model proposes that light particles within a mitochondrion couple to the collective vibrations of CH2 bonds. Together, they create a shared hybrid state known as a polariton, which has both light and matter properties.

This qualifies as a quantum effect because the coupled system is described as a superposition of light and molecular vibration, with separate quantised energy levels.

Under the model, the interaction divides the initial 87-terahertz vibration into two levels: one close to 71 terahertz, and a second close to 103 terahertz.

That is why these figures are important.

The predicted lower level corresponds with the unexplained 71-terahertz signal found in living samples. The upper level would coincide with vibrations from water and other biological molecules, so separating it would be difficult.

The mean length of active mitochondria corresponded to the wavelength of 87-terahertz light within them. This could mean mitochondria behave as microscopic chambers, briefly trapping light and allowing the interaction to occur.

Testing ATP production with infrared light

But would this suggested state serve a useful purpose?

Song suggests that it may. Its frequency overlaps with carbon dioxide vibrations. CO2 is generated in the tricarboxylic acid, or TCA, cycle, which supplies energy for ATP production.

In an earlier theoretical study, Song and colleagues suggested that NAD+ reduction in this cycle might emit 87-terahertz photons.

"The mitochondrial quantum state might increase the efficiency of TCA cycles, influencing the ATP production," he said.

This proposed mechanism has not been directly shown.

To investigate it, the researchers exposed living cells to low-intensity mid-infrared light for 10 minutes.

Light at 71 terahertz aligned with the unusual signal, whereas 87-terahertz light corresponded to the CH2 vibration believed to generate it.

The two frequencies produced much the same outcome. Exposure to 71-terahertz light raised ATP production by 10.3 percent, while 87-terahertz light increased it by 10.1 percent.

An unrelated control frequency produced no significant difference, implying that the effect relied on frequency rather than infrared exposure by itself.

The researchers interpret these results as evidence that the proposed quantum state might offer an energy-efficient way to influence ATP production.

Still, that conclusion is not conclusive.

An unusual spectral signal cannot establish that a quantum state is present. The polariton was inferred by fitting observations to a model, rather than observed directly. Alternative explanations still need to be ruled out.

The ATP test also used only one cultured human cell line, with eight samples per group. It does not establish that this mechanism regulates metabolism in entire animals or people.

Heating is another possible issue, though the light was very weak and the control frequency had no ATP effect.

"Our main limitation is the lack of 87-THz light-related energy transfer dynamics," Song added.

Studying those dynamics may help clarify the proposed connection. Separate laboratories will also need to replicate the signal and test directly for quantum behaviour.

For the moment, the results present an intriguing possibility: cellular power stations may operate through more than chemistry alone.

Within their deeply folded membranes, mitochondria could also make use of the unusual rules of quantum physics.

The research is available on bioRxiv.

This article was fact-checked by Fiona MacDonald and edited by Fiona MacDonald. Although we take pride in our process, we are only human. If you notice an error, please let us know.