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Dr Bruce Fraser was interviewed in 2008 for the Interviews with Australian scientists series. By viewing the interviews in this series, or reading the transcripts and extracts, your students can begin to appreciate Australia's contribution to the growth of scientific knowledge.
The following summary of Fraser's career sets the context for the extract chosen for these teachers’ notes. The extract discusses his studies into the structure of keratin, a protein found in wool. Use the focus questions that accompany the extract to promote discussion among your students.
Robert Donald Bruce (Bruce) Fraser was born in Ickenham (a village close to London) in 1924. Upon finishing school, Fraser began work at Kodak as a laboratory assistant and also studied part-time at London University. But, after one year, he interrupted his studies and joined the Royal Air Force. He was with the RAF from 1943 to 1946, where after training as a pilot he specialised in teaching pilot navigation.
After the war, Fraser returned to his studies and completed a BSc in physics at Kings College, London in 1948. In 1951, he received a PhD from the college for his studies into the application of polarised infra-red spectroscopy to the study of biological materials. He stayed on at Kings College in the biophysics department as a Nuffield Foundation Fellow (1951–52) and was involved in the work that led to the discovery of the molecular structure of DNA.
In 1952, Fraser and his young family immigrated to Melbourne where he took a position with the CSIRO’s Biochemistry Unit (later this became the Division of Protein Chemistry). He was with CSIRO for the remainder of his career. He developed robust mathematical and digital techniques for analysing x-ray diffraction data and used them to study the structure of wool keratin and other fibrous proteins.
After seven years at CSIRO, Fraser spent a sabbatical year in the UK learning about synthetic peptides. During that time he was awarded a DSc from London University (1960). He served as Acting Chief and Chief of the Division of Protein Chemistry from 1983 to 1987. In retirement, he has continued his intellectual work on fibrous protein structure including studies of goanna claw keratin. One of his recent publications was of a proposed structure for the filaments of feather keratin.
Over a long career, Fraser has received numerous honours and awards including the Science Medal (1982, Royal Society of Victoria), the SG Smith Memorial Medal (1984, the UK Textile Institute) and the Fogarty Scholarship to work at the USA National Institutes of Health (1985, 1987). He received the Australia Centenary Medal in 2001.
Fraser was elected a Fellow of the Australian Academy of Science in 1978.
Conformation in fibrous proteins
How did you apply your work in the UK with Arthur Elliott, on synthetic polypeptides, to fibrous protein studies such as in wool?
When I first got back, one of the big questions was, as always whenever you are interested in wool, the disulphide linkages. I can remember all the years you spent harvesting follicles! But perhaps a word of explanation is appropriate here. When wool is produced in the follicle, the cells synthesise keratin – of which wool, hair, nail, porcupine quills and other epidermal appendages are made – and initially it has no disulphide linkages; the proteins all assemble separately. Just before the fibre pops out of your head or the sheep’s back, however, a big change takes place and -SH [sulphhydryl] groups join up in pairs – boom, like that – and so you get the disulphide linkage. That is an absolutely essential part of making hair, wool or any other appendage completely water insoluble. One of the gruesome things I notice when I am trekking in the country is the skeletons of animals that have died, with the hair still there. It’s quite remarkable.
That’s right. It’s found in mummified animals, too.
Anyway, we coaxed Ian Stapleton, a very brilliant organic chemist in our laboratory, to make synthetic polypeptides, where you start with an amino acid – and join a string of them together. The first one was a derivative of cysteine. And the question we asked was: can those sulphur-containing, linking residues fit into the alpha helix, which is a vital part of the filaments? He managed to make the synthetic polypeptide for us, and we were able to take X-ray pictures and infra-red spectra which proved conclusively that it would adopt the alpha helix conformation. It means that a scheme was there for the filaments to link to other filaments and to the matrix through those disulphide bonds.
You did an equivalent thing with a silk-like peptide.
Yes, similar to that. For the next step we teamed up with another organic chemist, Fred Stewart. By this time it was just becoming possible to link together amino acids in some specified order. You could write down a sequence that you wanted to investigate, and Fred Stewart was an utter expert at joining them together. He did some excellent work there.
One of the things you could do, for example, was to ask the question: why is an alpha helix an alpha helix, and what happens if I incorporate in there this residue that is a little bit different? Can it still be an alpha helix? He made a whole series of sequential polypeptides for us. The first was an extremely interesting one, proving a point which you hinted at just now, that in silk there is a special sequence. (It’s actually got an extended chain, it’s not an alpha helix, but it was a good test of the whole concept.) A repeating sequence is the key to the structure of a lot of proteins, and this one, actually, was a very simple one. It was glycine, alanine, glycine, alanine, glycine, serine – and so it went on like this, and that repeated. He managed to make quite a high-molecular-weight synthetic one with exactly that sequence, and when we took the X-ray picture we could look at the pattern and hold it beside the one of actual commercial silk, the Bombyx mori silk that the Japanese produce, and see that they were identical. So it showed that the method could be used to check conformation in fibrous proteins. We were very excited about it.
Focus questions
Select activities that are most appropriate for your lesson plan or add your own. You can also encourage students to identify key issues in the preceding extract and devise their own questions or topics for discussion.
alpha helix
amino acids
disulphide linkage
keratin
polypeptide
protein conformation
wool
x-ray diffraction
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