Isolation and biochemical characterization of the microsomal fraction from the digestive gland of mussel Mytilus galloprovincialis Lam.

1. A procedure to prepare microsomes from the mussel digestive gLond is proposed. The data concerning the biochemical characterization of this subcellular fraction shows a typical RNA: protein ratio, but the presence of hydrolytic enzymes was also found; therefore a mixture of hydrolase inhibitors to study the different biochemical characteristics was used. 2. The biochemical data demonstrate that glucose-6-phosphatase activity (G6Pase), a typical microsomal marker in mammalian cells, is not present in mussel digestive gland microsomes but a high non-specific phosphatase activity was detected. 3. Benzo[a]pyrene hydroxylase activity was found to be present although in a minimal amount. 4. The evaluation of the molecular weight of the rRNA demonstrates that the larger ribosomal subunit contains RNA of M_r 1.40 × 10 ^-6 (~26S) and the smaller subunit is composed of RNA of M_r 0.65 × 10^-6 (18S). 5. The data from mussel digestive gland microsomes was compared with that experimentally obtained from rat liver microsomes and discussed from a functional or an evolutionary point of view.