Resilin

Resilin is a rubber-like elastomeric protein found primarily in the cuticle of insects and other arthropods. It forms highly elastic networks in joints such as wing hinges, leg articulations, and other flexible regions, enabling rapid and repeated movements with minimal energy loss.

Molecularly, resilin is a polypeptide-rich protein organized into flexible domains, whose network is crosslinked covalently by dityrosine linkages. These crosslinks create a resilient matrix that remains elastic under large strains. The protein is characteristically rich in glycine, proline and alanine, contributing to its soft, rubbery behavior. The crosslinking is often enzyme-mediated or oxidative, producing stable bonds that withstand cyclic loading.

Mechanical properties: Resilin exhibits a very low Young's modulus, typically in the order of 0.1–3 MPa, and can store and release energy efficiently, with resilience often exceeding 90%. It can sustain high cycle life with low hysteresis, allowing millions of cycles without fatigue.

Function: In insects, resilin acts as an efficient spring, providing energy storage for take-off, jumping, wing flapping, and fast movements. Its presence in joints reduces the energy required for movement and helps absorb shocks.

Applications: The exceptional elasticity and fatigue resistance have inspired biomimetic materials research, including resilin-like polypeptides and synthetic elastomers for soft robotics, flexible actuators, and medical devices.