Wolfgang Lubitz puts metalloproteins on the map. Joanne Thomson asks how...

Wolfgang Lubitz is managing director of the Max Planck Institute for Bioinorganic Chemistry in Mülheim, Germany. He is a member of the Board of Curators for the Annual Meetings of the Nobel Laureates in Lindau, Germany. His research work focuses on investigating catalytic metal centres in metalloproteins, the primary processes of photosynthesis and developing and applying electron paramagnetic resonance (EPR) methods and quantum chemical calculations.

Who inspired you to become a scientist?  

This inspiration certainly goes back to my early school days. I had a very good teacher in physics and chemistry when I was 13 or 14 years old and from this time on my strong interest in the sciences continued through my studies at university, intensified by my academic teachers. 

What drew you to metalloproteins?

In particular, the structure of the manganese cluster involved in oxygenic photosynthesis, the heart of light-induced water oxidation and oxygen release, strongly motivated me to get involved in the field of metalloproteins. Later on, I was intrigued by the enzyme hydrogenase, which produces hydrogen. Metal ions play a key role in this and many other proteins. About half of all enzymes contain metal ions and little is known about their detailed function. The field of bioinorganic chemistry is ideal for a spectroscopist. 

How does physical chemistry help to solve biological problems that other techniques cannot?

Physical chemistry and, in particular, spectroscopic methods are very important to identify and structurally characterise intermediates in biological reactions and so contribute to their detailed understanding. It is especially important to determine, not only the geometrical, but also the electronic structures of all species involved.  The excellent time resolution in, for instance, optical techniques allows the detection of very short-lived species and the high spectral resolution, for example of magnetic resonance, allows the precise determination of the electronic and spatial structure. The enormous sensitivity in the optical range even opens the possibility of observing single molecules. 

In my laboratory we concentrate on spectroscopy of paramagnetic species: transition metal complexes, organic free radicals and triplet states. Here, EPR is the method of choice. EPR and related techniques, like the double resonance method ENDOR [electron nuclear double resonance], deliver unique insight into the electronic structure of such molecules, for example the spin density distribution, and they profit from good time resolution (nanoseconds) and sensitivity. Spin labelling of proteins and other biological materials is a growing field which allows the application of EPR also to diamagnetic systems.

What are you working on at the moment?

Currently, we are interested in the two enzymes water oxidase and hydrogenase. This oxidase splits water and is located in the photosynthesis protein photosystem II of all green plants, algae and cyanobacteria [blue-green coloured bacteria]. Hydrogenase converts protons to hydrogen and vice versa in many microorganisms. Both transformations are highly interesting for future biotechnological applications, to produce environmentally clean fuels like hydrogen.

What's hot at the moment/going to be the next big thing in your field?

In case of the water oxidase, which is indeed a hot topic, we now have a good reliable structure of the active metal centre from a combined effort of x-ray crystallography and x-ray absorption spectroscopy. The next step will be elucidating the electronic structure of the tetranuclear metal cluster and the binding of the substrate water in the different states of the enzyme. This is exactly what we are working on in the Institute. This knowledge will finally lead to establishing a reaction mechanism, which is essential for drawing useful conclusions for artificial photosynthetic systems.

In the field of hydrogenases people are currently trying to understand why nature has developed different structures and metal centres to perform this simple chemical reaction. The inhibition by oxygen, and why some hydrogenases are not sensitive to oxygen, is a hot topic since this problem prevents the use of many highly active hydrogenases in biotechnology.

Part of your involvement with the Council for the Lindau Nobel Laureate Meetings includes organising scientific lecture meetings with Nobel Laureates, with audiences of young researchers, students and the media. How important is the media for the scientific community?

I am convinced that it is necessary to inform the public about our work much more extensively and thoroughly than has been done in the past. People are often not aware of the importance of results coming from basic research that will eventually lead to useful applications. We need the support of the public in many ways. I think, for example, of the sponsoring that is already very common in the US but unfortunately not in Europe. The most important addressees are, however, the young people, who must be inspired to get enthusiastic about the sciences. An excellent example is indeed the annual meetings of the Nobel laureates in Lindau with hundreds of young students from all over the world.

You have received numerous awards and honours during your career, including a Gold Medal of the International EPR Society. What do you think is the secret to successful research?

This is a difficult question. There are many facets, but I strongly believe that successful research is first of all driven by curiosity and a deep interest in solving the scientific problem at hand. 

What's the trickiest problem you've had to overcome in your research? How did you solve it?

We encountered a very difficult spectroscopic problem when we wanted to detect the nuclear resonances of the manganese cluster of photosystem II by performing ENDOR measurements. This was a crucial experiment in which all manganese ions of the cluster and their interactions with each other could be seen. We made many attempts to increase the sensitivity and stability of the instrument for the experiment, we changed the detection scheme, built our own probe head and also worked on getting stronger and better defined samples. The input came from different scientists working in diverse fields in our laboratory, and this multidisciplinary cooperation finally led to successful experiments.

We are currently building a new high field EPR machine with many new features and this turns out to be also very tricky. 

As science becomes increasingly interdisciplinary, how do you see the future of science, and chemistry in particular?

I believe that interdisciplinary research will become more and more important but this does not mean that a solid education in one particular field - like chemistry - will become less so. Modern chemistry, with an interdisciplinary approach, has a great future, in the development of new materials, catalysts and drugs, for example. However, one has to face that good research at the interface of two disciplines requires a profound knowledge of both fields, or at least a very close collaboration among different scientists. Such collaborations must be strengthened in the future. We also have to give our students a broader education and change the curricula accordingly. This is already under way at many universities.

If you could solve any scientific problem in any field, what would it be?

There are many problems in our world that are of high importance where scientists could contribute to a solution. Maybe the most important is how the energy needs of future generations can be secured in a world with an ever growing population. One possible solution might come from photosynthesis, a field that is very close to my heart. An artificial leaf would be the perfect solution - a catalyst driven by sunlight that efficiently splits water into hydrogen and oxygen. 

Do you remember your first experiment?

My first real scientific experiment was at the age of 16. I set up an electrochemical cell to measure the conductivity of dissociating liquids. This was an individual project required for a chemistry course at high school. As you see, my career actually started with physical chemistry.

And finally, if you weren't a scientist, what would you do?

My father always wanted me to become a businessman and study economics or law - but I decided against that option quite early. The next best thing to research in chemistry and physics, for me, would have been medicine; I would also have liked to be a practising physician.