Purification and properties of a rat liver phenobarbital-inducible 4-hydroxybiphenyl UDP-glucuronosyltransferase.
A phenobarbital-inducible rat hepatic microsomal UDP-glucuronosyltransferase (UDPGT) that catalyzes the glucuronidation of 4-hydroxybiphenyl (4-HBP) has been purified to homogeneity. This UDPGT has an apparent subunit molecular weight of 52,500, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The 4-HBP UDPGT was shown to catalyze the glucuronidation of 4-HBP, 4-methylumbelliferone, and p-nitrophenol but did not react with testosterone, androsterone, morphine, chloramphenicol, 4-hydroxycoumarin, or 7-methoxycoumarin. The apparent Km of 4-HBP UDPGT for 4-HBP was determined to be 0.26 mM and for UDPGA was 1.0 mM. Upon treatment with endoglycosidase H, the 4-HBP UDPGT underwent about a 2000-dalton decrease in subunit molecular weight, suggesting that this protein is N-glycosylated. Additionally, this protein demonstrated immunoreactivity with antibodies raised in rabbit against rat 17 beta-hydroxysteroid and 3 alpha-hydroxysteroid UDPGTs. This work describes the purification and characterization of a 4-HBP UDPGT from rat liver microsomes and, furthermore, provides evidence that suggests that this UDPGT is different from another UDPGT previously shown to react with 4-HBP and chloramphenicol.
Styczynski
P
P
Department of Pharmacology, University of Iowa, Iowa City 52242.
Green
M
M
Puig
J
J
Coffman
B
B
Tephly
T
T
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology; D004790:Enzyme Induction; D005260:Female; D014453:Glucuronosyltransferase / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism; D006031:Glycosylation; D008862:Microsomes, Liver / Q000737:chemistry / Q000201:enzymology*; D008969:Molecular Sequence Data; D010634:Phenobarbital / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013379:Substrate Specificity
D000906:Antibodies; C021788:4-methylumbelliferone glucuronyltransferase; D014453:Glucuronosyltransferase; D010634:Phenobarbital