Colouring Matters of the Aphidoidea XLII. Purification and Properties of the Cyclising Enzyme [Protoaphin Dehydratase (Cyclising)] Concerned with Pigment Transformations in the Woolly Aphid Eriosoma lanigerum Hausmann (Hemiptera: Insecta)

Abstract

Dried extracts of woolly aphid were treated with n-butanol, then by chromatography on DEAESephadex A50 and finally by filtration on Sephadex G150 to yield a substantially homogeneous protein catalysing the conversion of the aglucone of protoaphin into xanthoaphin. Traces of lowmolecular- weight contaminants were removed by chromatography on Sephadex G 100. The enzyme, which has a molecular weight of 120000±2000 and a high content of p-structure, was inhibited by naphthoresorcinol. Its glycoprotein nature was indicated by amino acid analysis.