Cuticular phenoloxidase from the silkworm, Bombyx mori: Properties, solubilization, and purification

Abstract

Some properties of cuticle-bound phenoloxidase from pupae of the silkworm, Bombyx mori, are described. Procedures for solubilization and partial purification of the enzyme are presented. The solubilized enzyme has been purified approximately nine hundred and thirty times with recovery of about 6 per cent. The purified enzyme can be classified as a laccase (E.C. 1. 10. 3. 2, p-diphenol: O 2 oxidoreductase), based on substrate specificity and insensitivity toward carbon monoxide. The enzyme has optimum pH at 5.5, and K m values of hydroquinone and l-dopa for the enzyme were found to be 2.44 × 10 −4 M and 1.33 × 10 −2 M, respectively. The enzyme activity appears at the very time when hardening and darkening of cuticle begin, reaches maximum about 4 hours after larval-pupal ecdysis, and scarcely remains 24 hours after the ecdysis.