title: 6 alpha-glucuronidation of hyodeoxycholic acid by human liver, kidney and small bowel microsomes.
abstract: Kinetic constants for the glucuronidation of hyodeoxycholic acid in man were determined using microsomal preparations of liver, kidney and small bowel. The affinity of hyodeoxycholic acid for the microsomal hepatic and extrahepatic enzymes was in the same range as previously observed for the monohydroxy bile acid lithocholic acid and about 3-14-times the affinity for the dihydroxy bile acids chenodeoxycholic, deoxycholic and ursodeoxycholic acids. The Vmax values for glucuronidation of hyodeoxycholic acid with hepatic microsomes were 10-30-times higher and with kidney microsomes 50-110-times higher than for the bile acids lacking a 6 alpha-hydroxy group. The site of glucuronidation was determined by gas chromatographic-mass spectrometric analysis of derivatives of products formed after periodate and chromic acid oxidation. Hyodeoxycholic acid glucuronides synthesized with microsomal preparations from the three organs were all found to be conjugated at the 6 alpha position. This has previously been shown to be the site of glucuronidation of endogenous hyodeoxycholic acid glucuronide excreted in urine.
authors.affiliation: Department of Physiological Chemistry, Karolinska Institutet, Stockholm, Sweden.
authors.forename: H U
authors.initials: HU
authors.lastname: Marschall
authors.forename: H
authors.initials: H
authors.lastname: Matern
authors.forename: B
authors.initials: B
authors.lastname: Egestad
authors.forename: S
authors.initials: S
authors.lastname: Matern
authors.forename: S
authors.initials: S
authors.lastname: Sjövall
mesh_terms: D001647:Bile Acids and Salts / Q000378:metabolism; D001665:Binding Sites; D002840:Chromates; D003840:Deoxycholic Acid / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D005965:Glucuronates / Q000378:metabolism*; D014453:Glucuronosyltransferase / Q000378:metabolism; D006801:Humans; D007421:Intestine, Small / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism*; D007700:Kinetics; D008861:Microsomes / Q000378:metabolism*; D008862:Microsomes, Liver / Q000378:metabolism*; D010084:Oxidation-Reduction; D010504:Periodic Acid
chemical_list: D001647:Bile Acids and Salts; D002840:Chromates; D005965:Glucuronates; D003840:Deoxycholic Acid; D010504:Periodic Acid; C010471:hyodeoxycholic acid; D014453:Glucuronosyltransferase; C034944:chromic acid