Scleroproteins, or fibrous proteins, constitute one of the three main classes of proteins, alongside globular proteins and membrane proteins.
Keratin, collagen, elastin, and fibroin are all scleroproteins. The roles of such proteins include protection and support, forming connective tissue, tendons, bone matrices, and muscle fiber.
A scleroprotein forms long protein filaments, which are shaped like rods or wires. Scleroprotein are structural proteins or storage proteins that are typically inert and water-insoluble. A scleroprotein occurs as an aggregate due to hydrophobic side chains that protrude from the molecule.
A scleroprotein's peptide sequence often has limited residues with repeats; these can form unusual secondary structures, such as a collagen helix. The structures often feature cross-links between chains (e.g., cys-cys disulfide bonds between keratin chains).
Scleroproteins tend not to denature as easily as globular proteins.
Miroshnikov et al. (1998) are among the researchers who have attempted to synthesize fibrous proteins.