title: Characterization of sericin powder prepared from citric acid-degraded sericin polypeptides of the silkworm, Bombyx Mori.
abstract: Acid-degraded sericin powder (AC-SP) was prepared from aqueous solution containing citric acid-degraded sericin polypeptides of Bombyx mori. The morphological and biochemical properties of AC-SP were compared with those of alkali-degraded sericin powder (AL-SP) and hot-water degraded sericin powder (HW-SP). Based on an SEM analysis, AC-SP showed a thin film structure of 10-100 microm with good dispersity while AL-SP and HW-SP had a much larger thin film structure (<500 microm). The extract of AC-SP showed stronger trypsin inhibitor activity due to cocoon shell trypsin inhibitor (CSTI-IV) than that of HW-SP. The extract of AL-SP showed no CSTI-IV activity. It was found that AC-SP was a trypsin inhibitor complex powder and that the release of CSTI-IV from AC-SP depended on pH and ion strength. Similar powder materials were obtained when such organic acids as tartaric acid and succinic acid were used. These results suggest that the acid-degraded sericin polypeptides work as a protein matrix to which CSTI-IV may bind ionically.
authors.affiliation: Silk Science Research Institute, Tokyo, Japan. akurioka@silk.or.jp
authors.forename: Akira
authors.initials: A
authors.lastname: Kurioka
authors.forename: Fujie
authors.initials: F
authors.lastname: Kurioka
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Yamazaki
mesh_terms: D000818:Animals; D012831:Bombyx / Q000737:chemistry*; D002021:Buffers; D002851:Chromatography, High Pressure Liquid; D019343:Citric Acid / Q000737:chemistry*; D003116:Color; D003902:Detergents / Q000494:pharmacology; D005612:Freeze Drying; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D010446:Peptide Fragments / Q000737:chemistry* / Q000494:pharmacology; D047030:Sericins / Q000737:chemistry* / Q000494:pharmacology; D014357:Trypsin / Q000378:metabolism; D014361:Trypsin Inhibitors / Q000302:isolation & purification / Q000494:pharmacology
chemical_list: D002021:Buffers; D003902:Detergents; D010446:Peptide Fragments; D047030:Sericins; D014361:Trypsin Inhibitors; D019343:Citric Acid; D014357:Trypsin