Purification of a phenobarbital-inducible morphine UDP-glucuronyltransferase isoform, absent from Gunn rat liver.
A morphine UDP-glucuronyltransferase (morphine UGTPB) was purified from liver microsomes of Sprague-Dawley rats treated with phenobarbital. UDP-glucuronyl-transferases in the liver microsomes were solubilized with Emulgen 911 and separated by omega-(beta-carboxypropionyl-amino)octyl Sepharose 4B column chromatography, which has been developed in our laboratory. Morphine UDP-glucuronyltransferases were eluted into two fractions, Peak I and Peak II, which have different substrate specificities. Morphine UGTPB was purified by two times of Chromato-focusing from Peak II which was more specific to morphine. The purified morphine UGTPB gave an apparent pI of 8.0 on chromatofocusing and displayed a subunit molecular weight of 55 kDa after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified enzyme catalyzed the glucuronidation of 3-hydroxyl group of morphine and small extent of 4-hydroxybiphenyl, but not of androsterone, bilirubin, chloramphenicol, codeine, 4-methylumbelliferone, 4-nitrophenol, testosterone, and 6-hydroxyl group of morphine. The N-terminal amino acid sequences of morphine UGTPB were identical to those of UGT1*01P which is deficient to homozygous Gunn rat. Peak II was absent from the fraction of omega-(beta-carboxypropionylamino)octyl Sepharose 4B column chromatography of liver microsomes of Gunn rats treated with phenobarbital, whereas morphine UGT in Peak I was PB-inducible in Gunn rats. Present results suggest that an isoform of morphine UDP-glucuronyltransferase belongs to the UGT1 family and is phenobarbital-inducible.
Ishii
Y
Y
Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
Tsuruda
K
K
Tanaka
M
M
Oguri
K
K
D000595:Amino Acid Sequence; D000818:Animals; D004790:Enzyme Induction; D014453:Glucuronosyltransferase / Q000302:isolation & purification / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009020:Morphine / Q000378:metabolism*; D010634:Phenobarbital / Q000494:pharmacology; D051381:Rats; D011911:Rats, Gunn / Q000378:metabolism*; D017207:Rats, Sprague-Dawley; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
D009020:Morphine; D014453:Glucuronosyltransferase; D010634:Phenobarbital