BACKGROUND: Carboxyl/cholinesterases (CCEs) are thought to play a pivotal role in the degradation of sex pheromones and plant-derived odorants in insect, but their exact biochemistry and physiological functions remain unclear. RESULTS: In this study, two paralogous antennae-enriched CCEs from Plutella xylostella (PxylCCE16a and 16c) were identified and functionally characterized. High-purity protein preparations of active recombinant PxylCCE16a and 16c have been obtained from Sf9 insect cells by Ni(2+) affinity purification. Our results revealed that the purified recombinant PxylCCE016c is able to degrade two sex pheromone components Z9-14: Ac and Z11-16: Ac at 27.64 +/- 0.79% and 24.40 +/- 3.07% respectively, while PxylCCE016a presented relatively lower activity. Additionally, a similar difference in activity was measured in plant-derived odorants. Furthermore, both CCEs displayed obvious preferences for the two sex pheromone components, especially on Z11-16: Ac (K(m) values in the range of 7.82-45.06 microM) than plant odorants (K(m) values are in the range of 1290-4030 microM). Furthermore, the activity of the two newly identified CCEs is pH-dependent. The activity at pH 6.5 is obviously higher than at pH 5.0. Interestingly, only PxylCCE016c can be inhibited by a common esterase inhibitor triphenyl phosphate (TPP) with LC(50) of 1570 +/- 520 microM. CONCLUSION: PxylCCE16c played a more essential role on odorant degradation than PxylCCE16a. Moreover, the current study provides novel potential pesticide targets for the notorious moth Plutella xylostella. This article is protected by copyright. All rights reserved.
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