21: Elegance in Molecular Design: The Copper Site of Photosynthetic Electron-Transfer Protein (1978)


  • Hans Charles Freeman School of Chemistry, University of Sydney


The Liversidge Research Lecture, delivered before the Royal Society of New South Wales, 19th July, 1978. Reproduced by permission of the Royal Society of New South Wales from J. Proc. Roy. Soc. N.S.W., 1979, 112, 45-62.

"Plastocyanin is an intensely blue protein which is essential for photosynthesis in green leaves and in some algae. The blue colour is associated with the presence of a single copper atom in each molecule of the protein. In terms of the absorbance per copper atom, plastocyanin is about a hundred times as blue as 'normal' cupric compounds. In addition, the protein has an unusual electron spin resonance spectrum and an anomalously high redox potential. The combination of these properties occurs in some other copper-proteins but has not yet been mimicked in any model compound of low molecular weight."

"The recent X-ray crystal structure analysis of plastocyanin has revealed a molecule ideally suited to the biological function which it performs. The nature of the copper site is such as to produce the high redox potential which is required for electron-transfer between plastocyanin and its neighbours in the photosynthetic chain. The location of the copper site in the protein molecule provides at least two reasonable electron-transfer pathways. The exterior of the molecule has distinctive features which suggest that the protein interacts in specific ways with its redox partners and/or its environment."

Author Biography

Hans Charles Freeman, School of Chemistry, University of Sydney

Hans Charles Freeman was born in 1929 in Germany, and his family arrived as refugees in Sydney in 1938. With a brief sojourn to California to begin his PhD, Freeman had a long association with the University of Sydney, where he completed his BSc, MSc, and PhD. He served as Head of the School of Chemistry from 1975–76, and from 1995–97 he was a Professor of Chemistry, before retiring formally as Professor Emeritus in 1998. His crystallographic work, especially in the area of metalloproteins, has led to numerous collaborative studies using techniques other than X-ray crystallography - particularly electronic and vibrational spectroscopies, and electrochemistry.


For additional biographical information, photographic permissions, references and a list of honours, awards and publications, please see pages 2–4 of the transcript.


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Hans Charles Freeman portrait.