Assay of intermediates in bile acid biosynthesis using isotope dilution--mass spectrometry: hepatic levels in the normal state and in cerebrotendinous xanthomatosis
The synthesis of 2H4-labeled 5 beta-cholestane-3 alpha, 7 alpha-diol, 5 beta-cholestane-3 alpha,7 alpha,12 alpha-triol, 7 alpha-hydroxy-4-cholesten-3-one, and 7 alpha,12 alpha-dihydroxy-4-cholesten-3-one is described. A mixture of these compounds, together with 2H3-labeled 5-cholestene-3 beta, 7 alpha-diol, was added to extracts of different subcellular fractions of liver. After purification by high performance liquid chromatography and conversion into trimethylsilyl ethers, the amounts of different endogenous unlabeled steroids were determined by selected ion monitoring. In normal liver, the concentration of 5-cholestene-3 beta, 7 alpha-diol was higher than the concentration of the other steroids. The concentration of the different steroids was highest in the microsomal fraction of the liver homogenate. In a liver sample from a patient with cerebrotendinous xanthomatosis (CTX), the amounts of the 12 alpha-hydroxylated steroids were considerably higher than in the normal liver. The levels of 7 alpha-hydroxy-4-cholesten-3-one and 5 beta-cholestane-3 alpha, 7 alpha-diol were similar or only slightly higher than in the liver of the control patients. The concentration of 5-cholestene-3 beta, 7 alpha-diol was very high in the mitochondrial fraction of the CTX-liver. The findings are in accordance with the previous demonstration that the basic metabolic defect in CTX is a lack of the mitochondrial 26-hydroxylase. The results are further compatible with the contention that 7 alpha,26-dihydroxy-4-cholesten-3-one is an important intermediate in the normal bile acid biosynthesis.
- OSTI ID:
- 5336922
- Journal Information:
- J. Lipid Res.; (United States), Journal Name: J. Lipid Res.; (United States) Vol. 22:2; ISSN JLPRA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
59 BASIC BIOLOGICAL SCIENCES
62 RADIOLOGY AND NUCLEAR MEDICINE
BILE ACIDS
BIOSYNTHESIS
BODY
CARBOXYLIC ACIDS
CHEMICAL ANALYSIS
COMPARATIVE EVALUATIONS
DIGESTIVE SYSTEM
DISEASES
ENZYME ACTIVITY
GLANDS
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LIVER
MASS SPECTROSCOPY
NERVOUS SYSTEM DISEASES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PATIENTS
QUANTITATIVE CHEMICAL ANALYSIS
QUANTITY RATIO
RADIOASSAY
RADIOIMMUNOASSAY
REACTION INTERMEDIATES
SPECTROSCOPY
STEROIDS
STEROLS
SYNTHESIS
TRACER TECHNIQUES