This is an informative article on a newly discovered role of collagen in the body.
The bodies of humans and animals owe their strength especially to a fibrous structural protein called collagen. Collagen is abundant in bones, tendons, ligaments and skin. Water, a substance that is not often associated with strength, was found out to be an intrinsic component of collagen
removing water from collagen fibres has dramatic effects on molecular and nanoscopic features. The fibres contract and generate tensile forces that are 300-times higher than those exerted by human muscles
These findings could help researchers develop novel materials and also suggest that collagen may have more active role in living organisms than previously thought. In fact, it does not act merely as a stabilising framework for the body, but can also generate tensions, for example during the synthesis of bones.
Like a building, collagen has a hierarchical structure consisting of a complex arrangement of individual molecular components. The basic building block is the collagen molecule itself.
Its shape reminds of a rope, with three chain-like proteins twisted around each other to form a triple helical motif.
Many of these “ropes” in turn combine to form thicker “coils,” known as collagen fibrils …just 100 to 500 nanometres thick
Within the fibrils, adjacent collagen molecules are not simply stacked one adjacent to each other but they are laid to form a staggered arrangement. This results in alternating denser and thinner zones along the length of the fibrils. Many fibrils in turn combine to form collagen fibres.
Water is an intrinsic component of collagen… In the protein’s natural state, water accounts for about 60 percent of the substance by weight. Given the high content of water in collagen, it is not surprising that its removal has dramatic effects
If the relative humidity is reduced from 95 to 5 percent, the collagen practically dries out, the collagen molecules shorten by 1.3 percent and the corresponding fibrils by 2.5 percent
a tensile force of around 100 megapascals is generated — some 300 times more than that produced by contractile muscle
The researchers found that contraction is caused by these conformational changes. This can be visualised by imagining a rope that is initially straight and shortens by forming wave-like patterns so that its ends are closer together. An interesting detail of the mechanism is that the denser regions of the fibrils elongate, while the thinner regions shorten. The net effect is contraction.
Potential and still unexplored active function of collagen fibrils
Although such massive dehydration as carried out in the researchers’ humidity chamber does not occur in the body of a living organism under physiological conditions, Masic’s and Bertinetti’s team found that the removal of water can be large enough, even under biological conditions, for collagen to generate as much tensile force as human muscles.
The biomolecule could therefore also play an active role rather than a purely passive elastic one — namely in mechanically stabilising the body. “During bone synthesis, water may be removed from collagenous matrix so that the tissue contracts”
Consequently, the bone would be compressed, thus preventing the mineral part, which is actually quite brittle, from being raptured by tensile stresses. The steel in reinforced concrete plays a similar role
This assumption is supported by the fact that the spacing between the dense zones of collagen fibrils in bone tissue is the same as that in dry collagen and that the tensile strength of bone corresponds approximately to the tensile strength of dried collagen.
Here’s a related article from Sept 2014:
esearch by a biomedical engineer at Texas A&M University is shedding light on how collagen grows at the molecular level and helps form a diverse set of structures in the body, ranging from bone, tendon, blood vessels, skin, heart and even corneas.
has been able to distinguish molecular-level differences in complex collagen networks formed under different conditions.
Collagen, while popularly known for its cosmetic uses, is the most abundant protein in the human body. As the main structural protein in connective tissues, it is found in tendons, ligaments and skin. It’s also abundant in corneas, cartilage, bones, blood vessels and teeth
examining how collagen fibrils assemble into ordered networks on surfaces.
collagen fibrils assemble into an intricate network of triangular shapes in which larger shapes are filled with smaller ones, iteratively. This type of structured network is characterized by scientists as fractal
“With this program [CAFE] we can measure filament lengths and orientations in a complex image,
When it comes to collagen formation, we need to understand what happens at the molecular level, and we need to be able to do this in a measurable way, quantitatively, to better understand how collagen grows and differentiates.