Fibrous proteins

Fibrous Proteins are a group of proteins that are characterized by their filamentous, elongated form and insolubility in water. They play a crucial role in the biological structure and function, providing support, shape, and protection to the cells and tissues in which they are found.

Structure

The structure of fibrous proteins is primarily composed of one type of secondary structure, the alpha helix or the beta sheet. This repetitive structure gives these proteins their characteristic fibrous shape. The most common types of fibrous proteins include collagen, keratin, and elastin, each with a unique structural arrangement.

Collagen

Collagen is the most abundant protein in the animal kingdom, making up about a third of the body's total protein content. It is a major component of connective tissues such as skin, tendons, ligaments, and bones. Collagen molecules are composed of three polypeptide chains coiled around each other, forming a triple helix.

Keratin

Keratin is a fibrous protein that forms the structural framework of epithelial cells in the skin, hair, and nails. It is also found in the internal organs and glands. Keratin proteins are rich in cysteine, an amino acid that forms disulfide bonds, providing strength and rigidity.

Elastin

Elastin is a fibrous protein found in connective tissues where elasticity is required, such as the skin, lungs, and arteries. It allows these tissues to resume their shape after stretching or contracting.

Function

Fibrous proteins have a variety of functions, primarily related to support and protection. For example, collagen provides tensile strength to tissues, preventing them from being torn or stretched too much. Keratin provides protection to epithelial cells from damage or stress. Elastin allows tissues to return to their original shape after being stretched.

Diseases

Abnormalities in the structure or amount of fibrous proteins can lead to various diseases. For instance, mutations in the genes encoding for collagen can result in Ehlers-Danlos syndrome, a group of disorders affecting the skin, joints, and blood vessels. Similarly, defects in keratin can lead to skin disorders such as epidermolysis bullosa.

See Also

• Protein structure
• Connective tissue
• Protein folding