Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.31 (beta-glucuronidase)
 7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Egasyn is an accessory protein of beta-glucuronidase (beta-G) in the liver microsomes. Liver microsomal beta-G is stabilized within the luminal site of the microsomal vesicles by complexation with egasyn which is one of the carboxylesterase isozymes. We investigated the effects of organophosphorus compounds (OPs) such as insecticides on the dissociation of egasyn-beta-glucuronidase (EG) complex. The EG complex was easily dissociated by administration of OPs, i.e. fenitrothion, EPN, phenthionate, and bis-beta-nitrophenyl phosphate (BNPP), and resulting beta-G dissociated was released into blood, leading to the rapid and transient increase of plasma beta-G level with a concomitant decrease of liver microsomal beta-G level. In a case of phenthionate treatment, less increase in plasma beta-G level was observed, as compared with those of other OPs. This may be explained by the fact that phenthionate was easily hydrolyzed by carboxylesterase. Similarly, carbamate insecticides such as carbaryl caused rapid increase of plasma beta-G level. In contrast, no significant increase of plasma beta-G level was observed when pyrethroid insecticides were administered to rats. This is due to the fact that pyrethroids such as phenthrin and allethrin were easily hydrolyzed by A-esterase as well as carboxylesterase. On the other hand, addition of OPs to the incubation mixture containing liver microsomes caused the release of beta-G from microsomes to the medium. From these in vivo and in vitro data, it is concluded that increase of the plasma beta-G level after OP administration is much more sensitive biomarker than cholinesterase inhibition to acute intoxication of OPs and carbamates.
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PMID:Toxicological significance in the cleavage of esterase-beta-glucuronidase complex in liver microsomes by organophosphorus compounds. 1042 85

Previous reports in animals considered beta-glucuronidase activity as a novel biomarker of anticholinesterase (organophosphates and carbamates) pesticides exposure. Acid phosphatase activity was also shown to increase after organophosphates exposure. In addition, there is evidence that the paraoxonase status influences sensitivity to specific pesticides. In this study, activities of beta-glucuronidase, acid phosphatase, cholinesterase, and paraoxonase were measured in plasma from plastic greenhouse workers exposed over the long term to different pesticides, including organophosphates and carbamates, in order to evaluate the potential chronic toxicity of pesticides at occupational level. Our results show that activities of paraoxonase and cholinesterase were decreased in applicators of pesticides compared to non-applicators. Likewise, it was found that activities of beta-glucuronidase and acid phosphatase were associated with pesticide exposure in humans, and that both biochemical parameters were related to each other. Interestingly, the paraoxonase B allele (phenotyped in plasma) was associated with a higher risk of inhibition of cholinesterase activity above a 25% level, which supports the hypothesis that paraoxonase phenotypes are associated with susceptibility of humans to anticholinesterase pesticides toxicity.
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PMID:Effect of long-term exposure to pesticides on plasma esterases from plastic greenhouse workers. 1520 26


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