Fibroins

Fibroins are a class of proteins that are structural components of connective tissues. They are particularly abundant in the extracellular matrix, a network of molecules that surrounds and supports cells. Fibroins play a crucial role in providing mechanical strength and elasticity to tissues, enabling them to withstand stress and deformation.

The most well-known fibroin is silk fibroin, the primary protein found in silk produced by silkworms and spiders. Silk fibroin is renowned for its remarkable tensile strength and flexibility. It is composed of repeating amino acid sequences, primarily glycine and alanine, which form crystalline regions within the protein structure. These crystalline regions are responsible for silk's impressive mechanical properties.

Other proteins that are sometimes referred to as fibroins or share similar structural characteristics include elastin, a protein that provides elasticity to tissues like skin, blood vessels, and lungs. Elastin's unique properties are due to its ability to stretch and recoil, returning to its original shape after being deformed.

The production of fibroins is a complex biological process. In silk production, specialized glands in silkworms and spiders synthesize and secrete fibroin in a liquid state. This liquid protein undergoes a transformation as it is extruded through a spinneret, becoming a solid fiber. This process involves changes in protein conformation and the formation of intermolecular bonds, leading to the formation of the strong and durable silk fiber. Research into fibroins continues to explore their potential applications in biomaterials, textiles, and medicine due to their biocompatibility and exceptional mechanical attributes.