The identity of cysteine proteinases and their distribution within several major coleopteran families.

Abstract

Based on the hydrolysis of synthetic substrates, pH optima for substrate hydrolysis and effects of potential activators and inhibitors, the identity and occurrence of cysteine proteinases in several major coleopteran families were investigated. The larval midgut of the Colorado potato beetle, Leptinotarsa decemlineata contains the cysteine proteinase cathepsin B and H, the aspartate proteinase cathepsin D and leucyl aminopeptidase. Cathepsin B and the serine proteinase trypsin were identified in the larval midgut of the yellow mealworm, Tenebrio molitor. Cathepsin B and the serine proteinase chymotrypsin were identified in the maize weevil, Sitophilus zeamais. The larger grain borer, Prostephanus truncatus, feeds on the same food source as S. zeamais but uses trypsin, chymotrypsin and leucyl and arginyl aminopeptidase and not cysteine proteinases for digestion. Trypsin, leucyl aminopeptidase and arginyl aminopeptidase and not cysteine proteinases were identified in a predacious carabid beetle, Pterostichus corvinus, a predacious tiger beetle, Cicindela sp. and a saprophagous hide beetle, Dermestes maculatus. (Abstract shortened by UMI.)