Studies on Immunological Properties of Fibroin Heavy and Light Chains1

Abstract

Silk fibroin is composed of heavy (H-) and light (L-) chains linked with disulfide bond(s). This paper describes immunological properties of fibroin H- and L-chains. Antiserum against H-chain, L-chain or whole fibroin could be obtained, indicating that each of these polypeptides is antigenic in rabbits. The antiserum against whole fibroin reacted with H- and L-chains. The antiserum against H-chain did not react with L-chain. Similarly, the anti-L-chain serum did not cross-react with H-chain. These results demonstrated that H- and L-chains have different antigenic determinant groups. Sericin-free fibroin samples prepared by boiling the cocoon protein in acid or 1% Na-oleate reacted with both anti-L-chain and anti-H-chain sera, indicating that the subunit structure of fibroin is stable under the drastic conditions of desericinization.