Despite centuries of meticulous experimental work, everyone from the science undergrad to the Nobel laureate still struggles to come to grips with the confusing and often counter-intuitive implications of quantum theory.
This complex giant of contemporary physics stipulates that all matter has both a solid particle nature and a wave nature. That something as small as a cell may have already mastered the intricacies of the theory is humbling experience for U of T researchers on the forefront of quantum mechanics and biochemistry.
In a recent study, researchers at the Institute for Optical Sciences reported that they had successfully switched a key molecule in bacteriorhodopsin (bR)-a photosynthetic pigment found in some types of bacteria-between two of its forms by manipulating the basic wave properties of matter. The retinol molecule in bR plays an important role in bacterial photosynthesis and its derivatives are essential to the human eye.
The changes in retinol were induced using light pulses that provided small amounts of energy, too weak to break or reform any of the molecular bonds, but strong enough to disrupt the ‘quantum coherence’ of the molecule. These disruptions in the ‘waviness’ of the molecule consistently produced the same result: the molecule switched back and forth from its ‘all-trans’ form to a ’13-cis’ form rather than the multitude of other forms it could have adopted.
Surprisingly, the two forms are exactly the same ones observed in many animal cells. Andrea Nagy, a Ph.D. student involved in the project, explained how the light pulses only affected a specific atomic bond on the entire molecule, causing it to “stretch like chewing gum” before rotating into a different position.
The low levels of energy used by the researchers were similar to levels available to biological cells, suggesting that cells may modify enzymes and proteins by upsetting their quantum coherence.
For Dr. Valentyn Prokhorenko, a research assistant in the group, this could be a result of evolution, meaning even primitive cells have been using quantum mechanics for their own purposes long before scientists came on the scene.
Changing molecules between its different forms is a vital process both in industry and nature. Optical data storage, for example, uses the computer language of ones and zeros to store information on different forms of a molecule.
“Several companies are already working on producing such devices,” said Nagy.
The researchers hope to see whether other kinds of rhodopsin, like those in visual systems, can be changed in the same way.
“The major motivation of mine,” said Prokhorenko, “[to continue with this work is] to understand…how smart creation on Earth is.”
