On 10 January 2012, John Walker delivered the 2012 Keilin Memorial Lecture of The Biochemical Society at the Society’s annual symposium in Cambridge, UK. He also received the 2012 Keilin Medal.
David Keilin was a distinguished biochemist, born in Russia. He worked at the Molteno Institute for Parasitological Research in Cambridge from 1925 until his death in 1963; he became the Quick Professor of Biology in 1932. He is renowned for discovering the pigmented proteins known as the cytochromes a, b and c ("cellular pigments") which he characterised with a simple hand-held spectroscope in the horse bot fly, Gasterophilus intestinalis. These experiments allowed him to discriminate the cytochromes from the pigmented haemoglobin molecules. He recognised the role of cytochromes in the process of respiration, setting the stage for the last 40 years of research, when their roles as carriers of electrons during the process of biological energy conversion have been worked out in exquisite detail. The connection with John Walker’s work is that most of cytochromes are found in the mitochondria, where the ATP synthase is the main beneficiary of the electron transfer events in which the cytochromes participate.