Biology – Proteins | e-Consult

Individual collagen molecules, after exiting the endoplasmic reticulum, assemble into larger structures. First, the alpha-helical collagen molecules assemble into a precursor molecule called tropocollagen. Tropocollagen consists of three collagen molecules that have coiled together to form a protofibril.

Next, multiple protofibrils associate laterally and longitudinally to form collagen fibrils. This association is driven by electrostatic interactions between positively charged amino acid residues on adjacent collagen molecules and by hydrophobic interactions. The arrangement of these fibrils is highly organized, with the collagen molecules arranged in a specific parallel fashion. This parallel arrangement, combined with the triple-helical structure of the individual collagen molecules, results in the high tensile strength of collagen fibres. The strong intermolecular hydrogen bonds between the collagen molecules within the fibrils further enhance their strength and resistance to stretching. The specific arrangement of the collagen molecules within the fibril gives collagen its characteristic strength and resilience, allowing it to withstand significant tensile forces.