How did you become interested in your current research?

Molecules of Rhodopsin, a protein that can distinguish colors, have a spiral structure (left: height 2nm) that is so beautiful it resembles a work of art. Its exterior is just like a building (right: height 170 m)!

Rhodopsin, the protein in human visual cells, is the best-known of the proteins that can distinguish colors. At the same time, there are salt lakes on earth that are more than 10 times saltier than the sea, and we know that bacteria living in such extreme environments also contain a protein almost exactly like human rhodopsin. We are trying to explain why such different organisms have proteins with the same function.

 

Why did you decide to become a researcher?

In high school I was interested in working in either electrical or chemical engineering (I think!). While I was studying engineering at university, I attended a memorable series of lectures on biophysical chemistry. This was the first time I understood that there was a field of research looking at what an organism was and how substances and life originated. That sparked a desire in me to study the origins of life more deeply, and I went on to graduate school to study pharmacology, where I studied the effects of pharmaceuticals on cellular membranes. I then became a university lecturer and was placed in charge of researching applications for proteins in the field of biotechnology, and now I am teaching and conducting research in the field of biophysics and polymer science, which is a discipline at the boundaries of physics, biology and chemistry, within the School of Science. Looking back, I feel that I was blessed with good teachers, but at the same time, the fact that my curiosity was piqued by those lectures was also a major factor.

 

What sort of equipment do you use to carry out what type of experiments?

NMR equipment uses a large-scale superconducting magnet (left). The protein sample is placed in the center of the magnetic field, and the computer analyzes the signal emitted from the nucleus (right). (The principle of NMR is also used in MRI computerized tomography scanning used in hospitals.)

 

Proteins are made up of molecules and atoms, but at the same time, they are a source of life. Their “function” is created from “extremely beautiful shapes.” We use nuclear magnetic resonance (NMR), a method of investigating nuclei, in order to look at each atom in a protein in which the amino acids are connected, and are continuing with our research to determine the 3D shape (structure) of protein molecules from the chemical bonding characteristics thereof.

 

What results do you expect to achieve in the future?

In humans, light received by the eye uses visual rhodopsin to transmit a signal to the brain via the nerves. We do not really understand, however, why brainless bacteria contain these color-distinguishing proteins. Recent research has shown that bacterial rhodopsin not only distinguishes between light, but also uses light energy to function as an optical ion pump, i.e., transporting ions. Changing your perspective can show you the same thing in a different way and lead to new discoveries. I am also engaged in teaching university students the importance of exploring functionality, by taking advantage of the gifts that organisms give us in the form of “shape” from a physical chemistry perspective. Perhaps in the future, research into rhodopsin may allow the discovery of new technologies for the use of light energy that are way ahead of our current solar cells. Today’s high school students and university students will, of course, play a primary role in this research!

 

References

(1) Demura, M., Functions and Structures of Peptides: The Code of the Helix Minimum, in “What do we understand from NMR?”, Corona (currently being printed)

(2) Demura, M., Kamiya, M., Aizawa T., Optical Ion Pumps, in Kawano K., Tanokura Y. (eds) Basic Structural Biology, Kyoritsu Shuppan, pp.150-156 (2008)