Digestive Enzymes of the Velvetbean Caterpillar (Lepidoptera: Noctuidae)

Teo, L.H.; Hammond, A. M.; Woodring, Joseph; Fescemyer, Howard W.

doi:10.1093/aesa/83.4.820

Cited by 13 publications

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“…The pH value of 10.5 for maximal proteolytic activity using both buffers corresponded to the second peak of pH 10.0 reported for this insect by Teo et al (34), who also found a peak of activity at pH 7.6. The alkaline optimum pH for azocasein hydrolysis strongly suggests the presence of serineproteinases in midgut extracts, confirming the occurrence of protein digestion in this insect (13).…”

Section: Discussionsupporting

confidence: 83%

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Perspectives of digestive pest control with proteinase inhibitors that mainly affect the trypsin-like activity of Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae)

Pereira

Dörr

Peixoto

et al. 2005

Braz J Med Biol Res

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The present study describes the main characteristics of the proteolytic activities of the velvetbean caterpillar, Anticarsia gemmatalis Hübner, and their sensitivity to proteinase inhibitors and activators. Midguts of last instar larvae reared on an artificial diet were homogenized in 0.15 M NaCl and centrifuged at 14,000 g for 10 min at 4ºC and the supernatants were used in enzymatic assays at 30ºC, pH 10.0. Basal total proteolytic activity (azocasein hydrolysis) was 1.14 ± 0.15 absorbance variation min -1 mg protein -1 , at 420 nm; basal trypsin-like activity (N-benzoyl-L-arginine-p-nitroanilide, BApNA, hydrolysis) was 0.217 ± 0.02 mmol p-nitroaniline min -1 mg protein -1 . The maximum proteolytic activities were observed at pH 10.5 using azocasein and at pH 10.0 using BApNA, this pH being identical to the midgut pH of 10.0. The maximum trypsin-like activity occurred at 50ºC, a temperature that reduces enzyme stability to 80 and 60% of the original, when pre-incubated for 5 and 30 min, respectively. Phenylmethylsulfonyl fluoride inhibited the proteolytic activities with an IC 50 of 0.39 mM for azocasein hydrolysis and of 1.35 mM for BApNA hydrolysis. Benzamidine inhibited the hydrolysis with an IC 50 of 0.69 and 0.076 mM for azocasein and BApNA, respectively. The absence of cysteine-proteinases is indicated by the fact that 2-mercaptoethanol and L-cysteine did not increase the rate of azocasein hydrolysis. These results demonstrate the presence of serine-proteinases and the predominance of trypsin-like activity in the midgut of Lepidoptera insects, now also detected in A. gemmatalis, and suggest this enzyme as a major target for pest control based on disruption of protein metabolism using proteinase inhibitors.

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Section: Discussionsupporting

confidence: 83%

“…Teo et al (34) have reported a pH of 7.6 for the midgut content of A. gemmatalis larvae. This discrepancy may be due to the different methods used by these investigators to estimate midgut pH that disrupted the regulatory process necessary to maintain it (35).…”

Section: Discussionmentioning

confidence: 99%