Purification and characterization of a biliverdin-binding protein from the molting fluid of the eri silkworm, Samia cynthia ricini (Lepidoptera: Saturniidae)

Abstract

1. 1. The biliverdin-binding protein (BBP) was found in the molting fluid of the saturniid silkmoth, Samia cynthia ricini at the time of the larval-pupal ecdysis. 2. 2. It was purified from the molting fluid using hydrophobic interaction chromatography, gel-filtration and high-performance liquid chromatography (HPLC). 3. 3. The highly purified BBP showed a M r of approximately 49,000 by gel permeation of HPLC analysis using a TSKgel G3000SW column. 4. 4. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed a single band of M r approximately 24,000, indicating that the native BBP is dimer. 5. 5. The blue coloration of BBP from the molting fluid was due to the presence of biliverdin type pigments, as judged from its absorption spectra. 6. 6. These results suggested that BBP from Samia molting fluid may be a new type of insecticyanin (INS).