A new study found that chemical citrate, merged with water, creates a viscous fluid between the nano-scale crystals of bone that acts as a shock absorber, allowing more flexibility within the bone.
Using a combination of NMR spectroscopy, X-ray diffraction, imaging and high-level molecular modeling, researchers at the University of Cambridge department of chemistry found that citrate layers in bone can hold mineral crystals together, prevent them from fusing and retain the water that stops bones from shattering under pressure.
“Bone mineral was thought to be closely related to hydroxyapatite,” Melinda Duer, MD, lead researcher, stated in a press release. “But what we’ve shown is that a large part of bone mineral — possibly as much as half of it — is made up of this goo, where citrate is binding like a gel between mineral crystals.”
Duer said without citrate, all crystals in bone mineral would collapse together into clumps, become inflexible and more likely to shatter, which may contribute to brittle bone diseases.
“The moment calcium and phosphate touch, they form a solid,” she stated in the release. “You end up with these expanding clumps of brittle crystal, with water and citrate relegated to the outside of them. That solid clump of mineral is the most stable structure. However, as soon as you stand on it, it shatters. We need to figure out how to stop the bigger holes forming in the protein matrix.”
The researchers said the findings may encourage a shift in focus for studying bone pathologies.
For more information:
Duer M. PNAS. 2014; doi.org/10.1073/pnas.1315080111.
Disclosure: The researchers have no relevant financial disclosures.
