Structure of the full-length tropoelastin calculated from X-ray scattering (left), neutron scattering (middle) and a representation of the two combined (right).
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Using neutron experiments and other state-of-the-art techniques, scientists have revealed the shape of the protein that gives human tissues their elastic properties. This discovery might lead to the development of new synthetic ‘elastin-like’ materials.
Elastins are used in applications as diverse as clothing, vehicles, tissue engineering and even space travel, so understanding how the structure of tropoelastin creates its exceptional elastic properties could have wide-ranging applications and benefits.
Elastin allows tissues in humans and other mammals to stretch, for example when the lungs expand and contract for respiration or when arteries widen and narrow over the course of a billion heart beats.
“All mammals rely on elastin to provide their tissues with the ability to stretch and then return to their original shape,” said researcher Dr Clair Baldock, from the University of Manchester’s Wellcome Trust Centre for Cell Matrix Research. “This high level of physical performance demanded of elastin vastly exceeds and indeed outlasts all human-made elastics. It is the co-ordinated assembly of many tropoelastins into elastin that gives tissues their stretchy properties and this exquisite assembly helps to generate elastic tissues as diverse as artery, lung and skin.
“We discovered that tropoelastin is a curved, spring-like molecule with a ‘foot’ region to facilitate attachment to cells. Stretching and relaxing experiments showed that the molecule had the extraordinary capacity to extend to eight-times its initial length and can then return to its original shape with no loss of energy, making it a near-perfect spring” added Dr Baldock.
An international team of researchers from the UK, Australia, USA and Europe have solved the complex structure of tropoelastin, the main component of elastin. The team used ISIS Neutron Source to provide complimentary data to support information gathered at Diamond Light Source, also at the Harwell Oxford campus; the European Synchrotron Radiation Facility (ESRF) in Grenoble, France, and the Advanced Photon Source (APS) in Chicago, USA. This breakthrough is the result of more than a decade of international collaboration. The group’s findings are published in the March issue of science journal PNAS.
The experiments at ISIS were conducted on the small angle neutron scattering (SANS) instrument Loq.
“Crucial initial data was gathered using X-ray scattering. A side effect of this technique is radiation damage to the delicate molecules in the samples. This heating of the proteins can cause the structure of the molecules to change,” explained ISIS instrument scientist Dr Sarah Rogers.
”Neutron techniques are non-destructive, so radiation damage is not a problem. Using small angle neutron scattering, the researchers were able to collect data that enabled them to confirm the genuine size and shape of the molecules. Combining the synchrotron and neutron data helps to create a full, accurate picture of the protein. Each step of the process is vital. Without neutron data, the results would not have possessed the same amount of integrity.”
Initiator and research project leader Tony Weiss, Professor in the School of Molecular Bioscience, The University of Sydney, added: “Tropoelastin’s extraordinary capacity to extend to eight-times its initial length and then return to its original shape, with no loss of energy, is nature showing us how to make an ideal nanospring.”
Beth Penrose (ISIS)
Research date: January 2011
For more information the PNAS article can be found at : http://dx.doi.org/10.1073/pnas.1014280108
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