Day to day we take water for granted. We drink it, wash in it, cook with it and generally can't live without it. But for science, water is a vital tool in helping to further understand complex molecular structures, with the potential to provide new information to assist future medical and industrial breakthroughs.
Day to day we take water for granted. We drink it, wash in it, cook with it and generally can't live without it. But for science, water is a vital tool in helping to further understand complex molecular structures, with the potential to provide new information to assist future medical and industrial breakthroughs.
By adding another neutron to the nucleus of hydrogen atoms they become the unusual non-radioactive isotope 'deuterium', which is found in 'heavy water'. When used to replace normal hydrogen in molecules, deuterium can show researchers how they are structured and interact in a unique way.
For example, if a protein is known to play a role in causing disease, being able to isolate and study different parts within that protein could help scientists get a clearer picture of its behaviour and why it may be causing the disease. This in turn could provide important information that may help find a cure or provide better therapies.
The process is called 'deuteration'. It's complex but incredibly useful in the quest to determine the role of molecules. The importance of deuteration in science has also now been recognised. So much so, Australia has its first biological and chemical deuteration facility, the only one of its kind in the southern hemisphere.
Based at the Australian Nuclear Science and Technology Organisation (ANSTO) in Sydney's south, the National Deuteration Facility (NDF) has commenced initial operation and over the next few months will be briefing universities and other potential users about what it has to offer.
Dr Peter Holden, who heads the facility, said Australia's role in understanding biological and organic material, or soft matter, is taking new steps forward, thanks to the NDF and the new neutron beam instruments attached to ANSTO's OPAL nuclear research reactor, which will support much of the research in this area.
When asked to explain the deuteration process in layman's terms, Peter said it would not be easy because of the complicated nature of the process, but aimed to do his best.
"Simply put, deuteration is when a molecule, or parts of a molecular complex, in a protein or other organic molecule is labelled with deuterium," said Peter. "This is done chemically by exchanging the normal hydrogen molecules (or 1H) in a chemical building block, with deuterium (2H) using heavy water as the source of deuterium.
"These deuterated building blocks are then used to make the molecule of interest. It is also possible to use friendly bacteria grown in heavy water to grow large molecules, like protein or DNA, which are labelled with deuterium," Peter explained. "When placed in a neutron beam instrument or using nuclear magnetic resonance spectrometry, the deuterium labelling allows scientists to 'see' contrast in molecular structures, which is not possible with any other process.
"The 'seeing' is done using neutrons. Here a neutron beam is sent from a nuclear research reactor, down a beam line to an instrument where it then passes through the sample. When the beam hits the nucleus in atoms of the sample, it causes the beam to scatter onto a detector, which then provides data about the sample.
"As deuterium has an extra neutron in its nucleus, the scatter pattern of the labelled part of the sample will be very different to other molecules which contain normal hydrogen, showing contrast and key differences within the molecular structure."
Peter also said Australia was starting a new stage in this type of science and that was very exciting for the scientific community.
"In the past we had to put samples in mixtures of normal and heavy water but while results were instructive, you could not get the detail that deuteration labelling achieves. Now we can take multi-component systems and resolve those components even if they are otherwise chemically similar, whereas in the past they would all look the same.
"So far we have produced deuterium-labelled molecules for use in a variety of investigations such as Alzheimer's and Parkinson's disease, the behaviour of environmentally friendly plastics and the development of new nano and biotech materials," said Peter.
"One ANSTO scientist used the deuteration and neutron scattering process to show how a particular enzyme in the body attacks cell membranes and to do this she used snake venom, which also contains this enzyme, and deuterated fat-like lipids to make the model cell membranes," said Peter.
"This type of work gives further understanding of how cell membranes interact with enzymes and therefore has implications for further understanding diseases, industrial processes or how drugs interact with cells in the body."
Peter further explained the two types of deuteration, biological and chemical, and both have different processes.
"In biodeuteration, a living system such as a bacteria or algae, are grown in heavy water (2H2O) and their molecules labelled. If all the hydrogen in the target molecule needs to be deuterated then deuterated carbohydrates are also used to feed the bacteria. The bacterial cells are then broken open and the labelled compounds such as proteins or DNA can be isolated and purified for use.
"In chemical deuteration molecules require harsher treatment, such as high temperature and pressure, and corrosive conditions, to force the carbon-hydrogen bonds to break and encourage the exchange of the normal hydrogen atoms with the deuterium. Adding small amounts of unusual metals like platinum or palladium makes this happen more quickly. The resulting labelled molecules are then used to artificially synthesise the molecule of interest."
For ANSTO's Tamim Darwish who works in chemical deuteration, the NDF offers an exciting career path.
"The science we will support through this facility has the potential to uncover many questions about the structure of molecules and no doubt there will be further developments over time, who knows what scientific discoveries lay ahead?" said Tamim.
Colleague Anthony Duff in biodeuteration said the facility would help scientists make full use of OPAL's new research instruments.
"Our biodeuteration laboratories are well set up to make it easier for biological and life-scientists to make use of OPAL's research instruments. Our purpose is to reduce barriers and make the new research infrastructure as readily available as possible," he said.
At ANSTO the neutron beam instruments most likely to be used for molecular work are Quokka and Platypus which can be used to study biological molecules in solutions and thin films or membranes.
The NDF is funded by ANSTO and the National Collaborative Research Infrastructure Strategy (NCRIS) - an initiative of the Australian Government. NCRIS identified a national need to invest in this technology which ANSTO was already using so it made a bid for the funding and it won.
Published: 15/06/2009