title: Even-numbered peptides from a papain hydrolysate of silk fibroin.
abstract: A protease with broad substrate specificity usually produces a complex peptide mixture. However, even-numbered peptides were obtained at high proportion upon papain hydrolysis of fibroin composed of highly repetitive Ala- and Gly-rich blocks. MALDI-TOF and ESI mass spectrometric analysis revealed that the even-numbered peptides were in the forms of di-, tetra-, hexa-, and octa-peptides with repeating units in combination of Ala-Gly, Ser-Gly, Tyr-Gly, and Val-Gly. Application of tandem mass spectrometry identified the sequences of the tetra-peptides to be in the order of Ala-Gly-X-Gly (X = Tyr or Val). Therefore, the substrate specificity of papain and the unique repetitive sequence of fibroin generated the hydrolysate composed of even number of amino acids at a high percentage. In this work, fibroin hydrolysate was investigated as an example of an end product of protein hydrolysis, which provides a clue to understand the fate of peptides in a protein hydrolysate.
authors.affiliation: The Center for Cell Signaling & Drug Discovery Research, Ewha Womans University, Seoul 120-750, Republic of Korea.
authors.forename: Jaeho
authors.initials: J
authors.lastname: Jeong
authors.forename: Won
authors.initials: W
authors.lastname: Hur
mesh_terms: D000818:Animals; D012831:Bombyx / Q000737:chemistry; D005349:Fibroins / Q000737:chemistry*; D006868:Hydrolysis; D010206:Papain / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*
chemical_list: D010455:Peptides; D005349:Fibroins; D010206:Papain