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Midgut proteinase activities in larvae of Anoplophora glabripennis (Coleoptera: Cerambycidae) and their interaction with proteinase inhibitors
Author(s) -
Bian Xueyu,
Shaw Brian D.,
Han Yifan,
Christeller John T.
Publication year - 1996
Publication title -
archives of insect biochemistry and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.576
H-Index - 66
eISSN - 1520-6327
pISSN - 0739-4462
DOI - 10.1002/(sici)1520-6327(1996)31:1<23::aid-arch2>3.0.co;2-y
Subject(s) - biochemistry , chymotrypsin , biology , midgut , exopeptidase , serine , trypsin , aminopeptidase , casein , leucine , serine proteinase inhibitors , carboxypeptidase , enzyme , serine protease , amino acid , larva , protease , botany
The major proteinase activities in the larval midgut of a common poplar tree borer, Anoplophora glabripennis, were characterised. Overall digestive capacity, as measured by casein hydrolysis, showed a pH optimum between 10 and 11.5, suggestive of serine endopeptidase activity. Trypsin, chymotrypsin, and chymotrypsin‐like activities were detected using specific p‐nitroanilide synthetic substrates and by use of specific serine endopeptidase inhibitors. These activities also showed pH optima in the extreme alkaline range. The absence of cysteine, aspartic, and metallo‐endopeptidases were confirmed using class specific proteinase inhibitors. The dominant exopeptidase in the midgut is leucine aminopeptidase with a pH optimum of 7–9. Carboxypeptidase a and b activity were barely detectable. A large range of serine endopeptidase inhibitors were screened and were found to vary widely in their ability to inhibit casein hydrolysis. Potato proteinase inhibitor 1 (a chymotrypsin inhibitor) and wheat‐germ trypsin inhibitor 1 inhibited particularly effectively in tandem and represent possible candidates for gene transformation to produce plants tolerant to this pest. © 1996 Wiley‐Liss, Inc.