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Roman Fischer
From brains and muscles, to stomach and skin – preserved soft tissues can offer unique insights into the past, and the lives of individuals. But up to now, this treasure trove of information has been largely inaccessible to science. In the new study, the team led by postgraduate researcher Alexandra Morton-Hayward (Department of Earth Sciences and Centre for Medicines Discovery, University of Oxford) developed the first robust method for extracting and identifying proteins from ancient soft tissues, then demonstrated its capability on archaeological human brain samples.
A key hurdle was finding an effective way to disrupt the cell membranes to liberate the proteins. After testing ten different strategies on samples from 200 year-old human brains excavated from a Victorian workhouse cemetery, the team discovered that urea (a major component of urine) successfully broke open the cells, liberating the proteins within.
Following extraction, the proteins are then separated with liquid chromatography, and identified using mass spectrometry (an analytical technique that separates proteins based on their mass and electrical charge). The team found that by coupling the liquid chromatography-mass spectrometry step with a method called high-field asymmetric-waveform ion mobility spectrometry (which separates ions based on how they move in an electric field), they could increase the number of proteins identified by up to 40%. This makes the technique a powerful approach to recover proteins from samples that are hard to analyse, including degraded or very complex mixtures.
Morton-Hayward said: ‘It all comes down to separation: by adding additional steps, you are more likely to confidently identify molecules of interest. It is a bit like dumping out a bucket of Lego: if you can start to discriminate between pieces by colour, then shape, then size, etc. the better chance you have of making something meaningful with it all.’
Read the full story on the University of Oxford website.