Sugars, not proteins, gives structure to bones

William Atkins
Thursday, 18 October 2007 06:58

Science - Health

According to British and German researchers, the structure of human bones is different than once thought. The primary growth mechanism for bones and the way to keep bones healthy is with sugars, not proteins.        

They found that the structure of human bone, specifically its rigidity, is primarily due to specialized sugars (carbohydrates). In the past, researchers thought that proteins, such as collagens and other macromolecules, were the primary organic molecules that controlled bone structure.

The article describing the researchers' result appears in the October 16, 2007 issue of the journal Chemistry of Materials, by the American Chemical Society. It is called “The Organic-Mineral Interface in Bone Is Predominantly Polysaccharide”.

The researchers include Erica R. Wise, Sergey Maltsev, M. Elisabeth Davies, Melinda J. Duer, Christian Jaeger, Nigel Loveridge, Rachel C. Murray, and David G. Reid. They are from the University of Cambridge, England; the Animal Health Trust in Newmarket, Suffolk, England; and the BAM Federal Institute of Materials Research and Testing, Berlin, Germany.

The article states, “Bone comprises organic and inorganic components in a complex composite which confers remarkable ability to withstand mechanical loading, adapt to the environment, and act as a mineral reservoir. Toughness and stiffness are supplied by the organic and mineral phases, respectively. The former is a matrix of proteins, mainly collagen, and other macromolecules including proteoglycans (PGs) rich in acidic glycosaminoglycans (GAGs). The latter is a hydroxylated calcium phosphate resembling the mineral hydroxyapatite.”

“Although the relationship between the two phases must be crucial to the properties of bone in health and disease, little is known about the macromolecules which constitute and stabilize the boundary.”

“The molecular interaction between these components is fundamental for strength, adaptation, and growth and will be key to new understanding of bone health problems; current literature is dominated by an assumption that it is proteins which stabilize the interface. However, in this communication we present a direct demonstration using solid-state NMR (SSNMR) that normal bone mineral contacts its organic matrix via polysaccharides, most likely GAGs in PGs.”

The researchers studied bones in horses with the use of nuclear magnetic resonance (NMR). Their conclusions were that proteoglycans (PGs) and acidic glycosaminoglycans (GAGs) controlled the mineralization of bones—that is, what causes new bones to grow and harden with minerals such as calcium phosphate.

Calcium phosphate minerals are composed of calcium ions and most often metaphosphates, orthosphosphates, or pyrophosphates; but sometimes hydrogen or hydroxide ions. About seventy percent of bones are composed of hydroxylapatite.

This discovery could be important in the future with respect to how bone disorders, such as osteoporosis, are treated.

In fact, one of the researchers, David Reid, said, "We believe our findings will alter some fundamental preconceptions of bone biology. On a practical level they unveil novel targets for drug discovery for bone and joint diseases, new biomarkers for diagnosis, and new strategies for developing synthetic materials that could be used in orthopaedics. They may also strengthen the rationale for the current popularity of over-the-counter joint and bone pain remedies such as glucosamine and chondroitin, which are based on GAG sugar molecules."