Journal article
Dopamine Is a Low-Affinity and High-Specificity Substrate for the Human UDP-Glucuronosyltransferase 1A10
Drug metabolism and disposition, Vol.37(4), pp.768-775
04/2009
Handle:
https://hdl.handle.net/2376/102998
PMCID: PMC2680538
PMID: 19116261
Abstract
The purpose of this work was to identify human UDP-glucuronosyltransferases
(UGTs) capable of glucuronidating dopamine. Using a sensitive liquid
chromatography-tandem mass spectrometry method, we screened all 19 known human
UGTs and found that only one enzyme, UGT1A10, catalyzed dopamine
glucuronidation at substantial rates, yielding both
dopamine-4-
O
-glucuronide (37.1 pmol/min/mg) and
dopamine-3-
O
-glucuronide (32.7 pmol/min/mg). Much lower (<2
pmol/min/mg) or no dopamine glucuronidation activity was found for all other
UGTs tested at 1 mM dopamine. Evaluation of the UGT1A10 expression pattern in
human tissues by quantitative reverse transcription-polymerase chain reaction
confirmed that it is mainly expressed in small intestine, colon, and adipose
tissue, whereas only low levels were found in trachea, stomach, liver, testis,
and prostate but not in brain. Dopamine glucuronidation assays using
microsomes from human liver and intestine corroborated these findings because
activity in intestinal microsomes was markedly higher than that in liver
microsomes. Moreover, the glucuronidation regioselectivity in intestinal
microsomes was similar to that of recombinant UGT1A10, and both enzyme sources
exhibited sigmoidal kinetics with substrate affinity (
K
A
)
values in the range of 2 to 3 mM. Examination of four UGT1A10 mutants, F90A,
F90L, F93A, and F93L, revealed lower dopamine glucuronidation in all of them,
particularly in F90A and F93A. Nonetheless, the substrate affinities of the
four mutants were similar to that of UGT1A10. It is interesting to note that
mutant F93L exhibited regioselectivity, conjugating dopamine at the 4-hydroxyl
(OH) position approximately 3 times more efficiently than at the 3-OH
position. These results shed new light on the structure and function of
UGT1A10 and indicate that dopamine may be a useful probe substrate for this
enzyme.
Metrics
7 Record Views
Details
- Title
- Dopamine Is a Low-Affinity and High-Specificity Substrate for the Human UDP-Glucuronosyltransferase 1A10
- Creators
- Katriina Itäaho - Division of Pharmaceutical Chemistry (K.I., P.U., R.K.) and Center for Drug Research (M.F.), Faculty of Pharmacy, University of Helsinki, Helsinki, Finland; Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, Massachusetts (M.C.); and Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas (A.R.-P.)Michael H Court - Division of Pharmaceutical Chemistry (K.I., P.U., R.K.) and Center for Drug Research (M.F.), Faculty of Pharmacy, University of Helsinki, Helsinki, Finland; Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, Massachusetts (M.C.); and Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas (A.R.-P.)Päivi Uutela - Division of Pharmaceutical Chemistry (K.I., P.U., R.K.) and Center for Drug Research (M.F.), Faculty of Pharmacy, University of Helsinki, Helsinki, Finland; Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, Massachusetts (M.C.); and Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas (A.R.-P.)Risto Kostiainen - Division of Pharmaceutical Chemistry (K.I., P.U., R.K.) and Center for Drug Research (M.F.), Faculty of Pharmacy, University of Helsinki, Helsinki, Finland; Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, Massachusetts (M.C.); and Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas (A.R.-P.)Anna Radominska-Pandya - Division of Pharmaceutical Chemistry (K.I., P.U., R.K.) and Center for Drug Research (M.F.), Faculty of Pharmacy, University of Helsinki, Helsinki, Finland; Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, Massachusetts (M.C.); and Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas (A.R.-P.)Moshe Finel - Division of Pharmaceutical Chemistry (K.I., P.U., R.K.) and Center for Drug Research (M.F.), Faculty of Pharmacy, University of Helsinki, Helsinki, Finland; Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, Massachusetts (M.C.); and Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas (A.R.-P.)
- Publication Details
- Drug metabolism and disposition, Vol.37(4), pp.768-775
- Academic Unit
- Veterinary Clinical Sciences, Department of
- Publisher
- American Society for Pharmacology and Experimental Therapeutics
- Identifiers
- 99900546509301842
- Language
- English
- Resource Type
- Journal article