Imperial College London

The big bang of evolution and the engine of life


Watch the video online now! Professor James Barber FRS presented the first annual Ernst Chain lecture in 2011, hosted by the Department of Life Sciences.

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Without doubt, one of the greatest contributions to medicine was the discovery of penicillin. This discovery, the development of its derivatives and the advances in medical sciences which followed has played a key role in the explosion of the global population. At the time when penicillin became routinely available the population of our planet was about 2 billion. Today, just over 60 years later, it is almost 7 billion and rising. It is a quite achievement that we are able to support so many people on our planet and strive to give all a good standard of living.  

But this comes at a cost. The cost is not only to feed this vast number of people but to provide the energy needed to satisfy their expectations. At the moment this energy comes mainly from burning fossil fuels (85%). Fossil fuels are derived from the process of photosynthesis which began in earnest 2.5 billion years ago. At that time a molecular catalyst was constructed within a protein environment which was able to absorb sunlight and use it to split water into oxygen and hydrogen. This was truly the “big bang of evolution” since for the first time biological organisms had an unlimited supply of hydrogen to power their metabolism which also became much more efficient as the atmosphere changed from anaerobic to aerobic.

Life could now prosper and diversify on an enormous scale and with the establishment of the ozone layer, able to explore new ecological niches, particularly the terrestrial environment. This water splitting enzyme is called Photosystem II (PSII) and is the “engine of life”.

Today we have a very good understanding of the molecular details of this enzyme, so much so that there is now a flurry of activity to construct catalysts which mimic it. The back drop to this activity are  concerns about the future supplies of fossil fuels and the cumulative nature of CO2 emissions in the atmosphere, possibly leading to dramatic perturbations in global climate patterns. To address these challenges by mid-century will require invention, development, and deployment of schemes for carbon-neutral energy production on a scale commensurate with, or larger than, the entire present-day energy supply from all sources combined.

Solar energy is the obvious choice since one hour of sunlight falling on our planet is equivalent to all of the energy consumed by humans in an entire year. If solar energy is to be a major primary energy source, it must be stored and dispatched on demand to the end user. An especially attractive approach is to store solar-converted energy in the form of chemical bonds as occurs in natural photosynthesis.

However a technology is needed which has a year-round average efficiency significantly higher than current plants and algae, to reduce land-area requirements and to be independent of food production. Therefore the scientific challenge is to construct an “artificial leaf” able  to efficiently capture and convert solar energy and then store the energy in the form of chemical bonds, producing oxygen and hydrogen from the photochemical splitting of water. The “artificial leaf” must be robust and constructed of abundant materials and with effort, there is no reason why such technology can not be created for future prosperity, sustainability and harmony for the human race. 


The first speaker of this lecture series is Professor James Barber FRS who is the Ernst Chain Professor of Biochemistry at Imperial. Professor Barber was educated at Portsmouth Southern Grammar School for Boys, University College, Swansea (BSc) and at the University of East Anglia (MSc, PhD). He joined Imperial College in 1968, was made Reader in 1974, and was promoted to Full Professor in 1979 (1979-89 Professor of Plant Physiology, 1889- present Chair).

He was Dean of the Royal College of Science, and from 1989 to 1999 was Head of the Biochemistry Department. Professor Barber was elected a member of the European Academy Academia Europaea in 1989, became foreign member of the Royal Swedish Academy of Sciences in 2003, and Fellow of the Royal Society in 2005. Professor Barber was awarded the Flintoff Medal by the Royal Society of Chemistry in 2002, the Italgas/Eni Prize for Energy and the Environment in 2005, the Biochemical Society Novartis medal and prize in 2006, and the Wheland Medal and Prize from the University of Chicago in 2007. He was awarded honorary doctorates of Stockholm University in 1992 and from the University of East Anglia in 2010.  He has recently served as President of the International Society of Photosynthesis Research. He has given many named lectures and in 2008 was the Lee Kuan Yew Distinguished Visitor to Singapore.

Professor Barber has published over 500 research and review articles and produced 16 books covering various aspects of photosynthesis research. The focus of his research has been the investigation of photosynthesis and the functional role of the photosystems with emphasis on their structures. Much of his work has focused on Photosystem II, a biological machine able to use light energy to split water into oxygen and reducing equivalents.

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