Identification of isopeptidase activity in the midgut of insects： Purification, properties and nutritional ecology of a Hofmannophila pseudospretella （Lepidoptera： Oecophoridae） larval enzyme  

作　　者：Robert M. Simpson John T. Christeller 

机构地区：[1]Plant and Food Research Institute, Tennant Drive, Palmerston North 4474, Private Bag 11 030, New Zealand

出　　处：《Insect Science》2010年第4期325-334,共10页昆虫科学（英文版）

摘　　要：A γ-glutamyl transpeptidase （isopeptidase） has been purified 580-fold to homogeneity from the midgut of keratinophagous larvae of Hofmannophila pseudospretella. The enzyme is a single polypeptide of molecular mass 80 kDa. The enzyme was identified by its hydrolytic activity against the synthetic substrate, γ-glutamyl-AMC, its molecular mass and inhibition profile compared to other γ-glutamyl transpeptidases. The enzyme is low or absent from most other insect digestive systems apart from other keratinophagous lepidopteran larvae and predatory carabids. While isopepfide bonds are present in high levels of the proteins in the diet of keratinophages, their presence in the diet of predatory beetles has not been established.A γ-glutamyl transpeptidase （isopeptidase） has been purified 580-fold to homogeneity from the midgut of keratinophagous larvae of Hofmannophila pseudospretella. The enzyme is a single polypeptide of molecular mass 80 kDa. The enzyme was identified by its hydrolytic activity against the synthetic substrate, γ-glutamyl-AMC, its molecular mass and inhibition profile compared to other γ-glutamyl transpeptidases. The enzyme is low or absent from most other insect digestive systems apart from other keratinophagous lepidopteran larvae and predatory carabids. While isopepfide bonds are present in high levels of the proteins in the diet of keratinophages, their presence in the diet of predatory beetles has not been established.

关 键 词：γ-glutamyl transpeptidase Hofmannophila pseudospretella isopeptidase keratinophagous nutritional ecology 

分 类 号：Q966[生物学—昆虫学] S482.3[农业科学—农药学]