Characterization of Bombyx mori Sericins by the Partial Amino Acid Sequences

Abstract

To confirm the correspondence between sericin proteins and sericin genes of Bombyx mori, the partial amino acid sequences of cocoon sericins were determined by N-terminal sequencing of lysyl endopeptidase fragments and were then compared to the polypeptides derived from the Ser1 gene. It was determined that sericin M, which is the abundant component of sericin, was a product of the Ser1 gene, whereas sericin A, which distributes mainly in the floss and the outer layer of the cocoon, was not. In addition, sericin P was considered to be a smaller product of the Ser1 gene based on the cleavage pattern in the enzymatic digestion. It is expected that the properties of sericin A are different from those of sericins M and P because it does not have 38-amino acid repeats that constitute the major portion of the Ser1 proteins.