Inhibition of housefly microsomal epoxidase by the eye pigment, xanthommatin

Schonbrod, R. D.; Terriere, L. C.

doi:10.1016/0048-3575(71)90173-8

Cited by 38 publications

(7 citation statements)

References 11 publications

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“…The pellet was resuspended with 25/~1 with resuspension buffer by repeated gentle aspiration into a 200/~1 plastic disposable pipet and stored at -80 ~ Protein assays were performed according to Bradford (1976). Cytochrome P450 reductase assays were done according to Schonbrod and Terriere (1972). Ethoxycoumarin-O-deethylase (ECOD) activity was determined by the method of Lee and Scott (1989b).…”

Section: Methodsmentioning

confidence: 99%

Rapid microsome preparation from limited numbers of house flies

Wheelock¹,

Scott²

1991

Entomologia Exp Applicata

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Section: Methodsmentioning

confidence: 99%

Rapid microsome preparation from limited numbers of house flies

Wheelock¹,

Scott²

1991

Entomologia Exp Applicata

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“…Microsome preparations from some species may be further complicated by the presence of endogenous inhibitors of microsomal oxidases. Notable cases have been reported from insect studies (Wilkinson and Brattsten, 1972), where materials such as eye pigment (xanthommatin) (Schonbrod and Terriere, 1971;Wilson and Hodgson, 1972) and digestive proteases of the gut (Krieger and Wilkinson, 1970;Brattsten and Wilkinson, 1973) often present serious problems. The procedure providing the highest recovery of microsomal oxidase activity often results in considerable contamination of the microsomal fraction with extramicrosomal components.…”

Section: Morphological Chemical and Enzymatic Composition Of Micmentioning

confidence: 97%

Microsomal Oxidation and Insecticide Metabolism

Nakatsugawa

Morelli

1976

Insecticide Biochemistry and Physiology

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“…However, some organisms contain proteases and/or inhibiting agents in the eyes and/or guts (Gilbert & Wilkinson, ; Schonbrod & Terriere, ), which inhibit the enzymes before activity measurements can be performed. Agents interfering specifically with CYP activity have been identified in, for example, gut tissue from the honeybee, Apis mellifera (Gilbert & Wilkinson, ), southern armyworm, Prodenia eridania (Krieger & Wilkinson, ), and the house cricket, Acheta domesticus (Benke & Wilkinson, ), and in the eyes of the housefly, Musca domestica (Schonbrod & Terriere, ). CYP enzymes oxidize their substrates using NADPH as the electron donor through specific reductase enzymes (Shaik & De Visser, ).…”

Section: Introductionmentioning

confidence: 99%

“…Proteolytic gut enzymes interfere with CYP activity by releasing NADPH‐cytochrome c reductase from the microsomal membrane and hence disrupt the NADPH‐dependent reduction in enzyme‐substrate complex (Orrenius, Berggren, Moldéus, & Krieger, ). The eye pigment xanthommatin, on the other hand, has been established as a CYP inhibitor due to its ability to impede the flow of electrons from NADPH to cytochrome P450 (Schonbrod & Terriere, ). The interference of proteolytic enzymes in enzyme assays may be overcome by addition of specifically designed protective protease inhibitors.…”

Section: Introductionmentioning

confidence: 99%

Quantification of the activity of detoxifying enzymes in terrestrial invertebrates: Optimization, evaluation and use of in vitro and ex vivo methods

et al. 2019

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1. The negative effects of pesticides on beneficial terrestrial invertebrates have received much attention, and in this context quantification of the activity of metabolic enzymes provides an important tool. Unfortunately, current methodologies are limited in their use.2. In this study, the grain beetle, Tenebrio molitor was used to illustrate why in vitro methods are ineffective to quantify metabolic enzymes in some insects. It was further used to optimize an ex vivo assay that can replace in vitro methods when these are ineffective. The ex vivo method can quantify metabolic enzymatic activities of cytochrome P450 mixed function oxidases (CYPs), general esterases (EST) and glutathione S-transferases (GST).3. In detail we show, that T. molitor produces inhibitory and/or degrading agents, which are released during tissue homogenization. As these agents inhibit the in vitro CYP activity of rat liver microsomes we suggest, that they are also responsible for the lack of in vitro CYP activity of T. molitor. We tested the effectiveness of broad-spectrum protease inhibitors as protective agents and found, that they were only effective in concentrations that also interfered directly with the activity of CYP enzymes. As an alternative to in vitro measurements, we optimized an ex vivo method for quantification of CYP, EST and GST on individual gut systems of T. molitor. Our ex vivo method advances previous ex vivo methods, by allowing quantification of three major enzyme families, all in a single individual, and by exploiting real-time kinetic measurements of the enzymatically produced product.4. Subsequently, our method was successfully tested for its use on three different life stages: larvae, pupae, and adult insects from T. molitor and Apis mellifera. The method shows promise for expansion to other species and potentially other enzyme families and/or substrates. K E Y W O R D SApis mellifera, detoxification, enzymatic activity, ex vivo, in vitro, Tenebrio molitor, terrestrial insect | 727Methods in Ecology and Evoluঞon PEDERSEN Et al.

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Inhibition of housefly microsomal epoxidase by the eye pigment, xanthommatin

Cited by 38 publications

References 11 publications

Rapid microsome preparation from limited numbers of house flies

Rapid microsome preparation from limited numbers of house flies

Microsomal Oxidation and Insecticide Metabolism

Quantification of the activity of detoxifying enzymes in terrestrial invertebrates: Optimization, evaluation and use of in vitro and ex vivo methods

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