Pectin methylesterase from the rice weevil, Sitophilus oryzae (L.) (Coleoptera : Curculionidae): Purification and characterization

A pectin methylesterase was purified to apparent homogeneity from the adult rice weevil, Sitophilus oryzae (L.), by Q-Sepharose and S-Sepharose chroma tographies followed by high-performance anion-exchange chromatography. The resulting preparation is the first pectin methylesterase which has been pur ified from any animal species, although at this point we cannot rule out th e possibility that the enzyme is produced by a symbiotic microorganism. The molecular mass of the enzyme was estimated as 38 kDa by sodium dodecyl sul fate-polyacrylamide gel electrophoresis. This mass is similar to those of p ectin methylesterases previously isolated from bacteria, fungi, and plants. The purified enzyme had a broad pH optimum between 6 and 7, which appears consistent with the enzyme's probable site of action, the gut. (C) 1999 Pub lished by Elsevier Science Ltd. All rights reserved.