How do collagen fibers differ from elastic fibers?

Collagen fibers and elastic fibers differ significantly in their composition, structure, and physical properties:

• Composition: Collagen fibers are composed of the protein collagen, which is rich in glycine, proline, hydroxyproline, and hydroxylysine. In contrast, elastic fibers are composed of the protein elastin, which is rich in glycine, proline, and valine, and contains the unique amino acid desmosine.1
• Structure: Collagen fibers consist of organized, cross-striated unit fibrils that assemble into bundles. Elastic fibers lack these uniform subunits; they appear as amorphous material or an amorphous core surrounded by minute fibrils.1
• Physical Properties: Collagen fibers are characterized by great tensile strength and resistance to stretching, making them ideal for supporting structures like tendons and ligaments. Conversely, elastic fibers are highly distensible and possess the ability to recoil like rubber bands when stretched.21
• Chemical Resistance: Collagen is soluble in hot water (forming gelatin), whereas elastic fibers are extremely resistant to hot water, strong alkali, and digestion by trypsin, though they can be broken down by the enzyme elastase.1