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Researchers from the Faculty of Natural Sciences at Chemnitz University of Technology have discovered fat molecules in natural collagen fibrils, the main component of connective tissue. Their , published in Soft Matter, shows how fats affect the mechanical properties and water content of collagen fibrils.

Collagen fibrils are the basic building blocks of skin, tendons, ligaments, and bones. They hold our bodies together. Fats and oils have long been used to soften and protect leather, which consists of collagen molecules. However, it is not known how many fat molecules are contained in natural collagen fibrils.

Knowing the precise chemical composition of collagen fibrils is important for understanding biochemical processes involved in tissue growth, aging, and disease. In chemistry, the various molecular components are usually separated to study the properties of pure substances. However, biological systems contain thousands of different chemical molecules, all of which are likely important.

The team of physicists and chemists from the Faculty of Natural Sciences at Chemnitz University of Technology discovered that triacylglycerols鈥攁 very common type of natural fat molecule鈥攁ssemble between collagen molecules, thereby influencing the cohesion of much larger collagen fibrils. This finding is essential for understanding the biomechanics of connective tissue. It also demonstrates how embedded lipids can affect binding forces between proteins at the molecular level.

The researchers examined collagen fibrils from chicken tendons and discovered that they contained an unexpectedly high amount of triacylglycerols, also known as neutral fats. These fat molecules comprise about 9% of the volume of dry collagen fibrils and are randomly incorporated into the crystal lattice of collagen molecules. The fat molecules act as plasticizers, reducing the water content of the collagen fibrils. This finding challenges the current understanding of the chemical composition of natural collagen fibrils.

To determine the triacylglycerol content and its effects on the mechanical properties of individual collagen fibrils, Dr. Martin Dehnert and Prof. Dr. Robert Magerle of the Chair of Chemical 糖心视频ics at Chemnitz University of Technology developed a new analysis protocol based on atomic force microscopy.

They used a washing sequence in which the fats adhering to the fibrils are first removed with a nonpolar solvent (hexane). Then, they dissolved the fat molecules out of the interior of the fibrils using a polar solvent, a mixture of dichloromethane and methanol.

After each washing step, they examined the resulting changes in the collagen fibrils using atomic force microscopy. This allows the shape and mechanical properties of the collagen fibrils, which are approximately 100 nanometers thick, to be determined very accurately. Finally, using Raman and NMR spectroscopy, they identified the fats contained in the collagen fibrils as triacylglycerols.

"Our findings show how fats and water interact in natural collagen fibrils," explains Magerle. He adds, "This suggests that there may be a link between the fats present in our diet and the biomechanics of connective tissue. We plan to investigate this in more detail in the future."