The Glucuronidation of Exogenous and Endogenous Compounds by Stably Expressed Rat and Human UDP-Glucuronosyltransferase 1.1
| Autor: | Gladys R. Rios, Ida S. Owens, Mitchell D. Green, Birgit L. Coffman, Warren P. Bishop, Thomas R. Tephly, Christopher D. King |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
Narcotics
Bilirubin Biophysics Glucuronidation Glucuronates Endogeny Nalorphine In Vitro Techniques Pharmacology Transfection Biochemistry Naltrexone Cell Line Substrate Specificity Xenobiotics chemistry.chemical_compound Species Specificity medicine Animals Humans Glucuronosyltransferase Molecular Biology Crigler-Najjar Syndrome chemistry.chemical_classification Molecular Structure Recombinant Proteins Buprenorphine Rats Amino acid Kinetics Enzyme Liver chemistry Glucuronide medicine.drug |
| Zdroj: | Archives of Biochemistry and Biophysics. 332:92-100 |
| ISSN: | 0003-9861 |
| DOI: | 10.1006/abbi.1996.0320 |
| Popis: | Rat and human UDP-glucuronosyltransferase (UGT)1.1 share >70% identity in their deduced primary amino acid sequences. We have previously shown that rat UGT1.1, stably expressed in human embryonic kidney 293 cells, catalyzes the glucuronidation of bilirubin and the mixed opioid agonist/antagonist buprenorphine with high efficiency. The present study was designed to characterize the reactivity of expressed human UGT1.1 with opioid compounds and compare its substrate specificity for opioids to that of the expressed rat enzyme. The results show that both rat and human UGT1.1 catalyze the glucuronidation of opioids with a relative reactivity of buprenorphine >> nalorphine ≈ naltrexone. Comparison of glucuronidation activities in livers from Crigler–Najjar type 1 patients and normal patients indicates that UGT1.1 catalyzes at least 75% of buprenorphine conjugation in normal human liver. In separate studies, the reactivity of expressed rat UGT1.1 was characterized toward various xeno- and endobiotics of various compound classes. It was found that both rat and human UGT1.1 exhibited comparable substrate specificities and efficiencies (Vmax/Km) of glucuronide formation for anthraquinones, coumarins, estrogens, flavonoids, and phenolic compounds. Neither rat nor human UGT1.1 catalyzed the glucuronidation of amines, monoterpenoid alcohols, androgens, or progestins. In general, these data indicate that rat and human UGT1.1 are functionally identical and can be considered orthologous enzymes. |
| Databáze: | OpenAIRE |
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