title: Enzymatic determination of serum 12 alpha-hydroxy bile acid concentration with 12 alpha-hydroxysteroid dehydrogenase.
abstract: A simple colorimetric enzymatic assay for determination of serum 12 alpha-hydroxy bile acids was developed using 12 alpha-hydroxysteroid dehydrogenase (HSD). The enzymes were extracted from Bacillus sphaericus. The principle of the method is as follows: 12 alpha-hydroxy bile acids are converted to 12-oxo bile acids using 12 alpha-HSD with the conocomitant reduction of NAD to NADH, and then the hydrogen of the generated NADH is transferred by diaphorase to NTB to yield diformazan. Finally, the color of resultant diformazan was measured. The specificity and precision of this assay method were satisfactory. A linear relationship was noted between the amount of 12 alpha-hydroxy bile acids and the degree of absorbance in the range of 6.7 to 215 microM. The fasting values for serum 12 alpha-hydroxy bile acid in 10 patients with liver diseases ranged widely from 7.6 to 91.1 microM, and values obtained with this assay agreed closely with those obtained by gas-liquid chromatography (r = 0.94, p less than 0.001). The assay is convenient, rapid, and specific for the measurement of 12 alpha-hydroxy bile acid concentrations in the serum of patients with liver diseases.
authors.affiliation: Third Department of Internal Medicine, Hirosaki University School of Medicine, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Tamasawa
authors.forename: M
authors.initials: M
authors.lastname: Yoneda
authors.forename: I
authors.initials: I
authors.lastname: Makino
authors.forename: K
authors.initials: K
authors.lastname: Takebe
authors.forename: S
authors.initials: S
authors.lastname: Ueda
authors.forename: H
authors.initials: H
authors.lastname: Misaki
mesh_terms: D000328:Adult; D000368:Aged; D001647:Bile Acids and Salts / Q000097:blood*; D003124:Colorimetry / Q000379:methods; D005260:Female; D006801:Humans; D006913:Hydroxysteroid Dehydrogenases; D008107:Liver Diseases / Q000097:blood; D008297:Male; D008875:Middle Aged
chemical_list: D001647:Bile Acids and Salts; D006913:Hydroxysteroid Dehydrogenases; C019189:12 alpha-hydroxysteroid dehydrogenase