The association of mannitol oxidase with a distinct organelle in the digestive gland of the terrestrial slug Arion ater

Abstract

Post nuclear supernatants prepared from homogenates of the digestive gland of the slug Arion ater were analysed by rate-dependent and density-dependent density gradient zonal centrifugation. Mannitol oxidase carrying structures exhibited distinct centrifugal behaviour sedimenting more slowly than mitochondria, lysosomes and peroxisomes but faster than microsomes, and banding sharply at a density of 1.15 g/ml in sucrose gradients. By combining rate and isopycnic centrifugations mannitol oxidase carrying structures were largely separated from contaminating organelles. Electron microscopic examination of such mannitol oxidase-enriched fractions revealed the predominant presence of distinct structures of tubular form. SDS PAGE analysis indicated that the major polypeptide present had a mass of ∼ 68 kDa corresponding to the major subunit previously reported for partially purified mannitol oxidase of Helix aspersa. © 1993 Springer-Verlag.