Isotope derivative assay of microsomal cholesterol 7 α-hydroxylase
نویسندگان
چکیده
منابع مشابه
Bile acid synthesis in man: assay of hepatic microsomal cholesterol 7~hydroxylase activity by isotope d ilution-mass spectrometry
The present work describes an accurate assay of the rate-limiting enzyme in bile acid synthesis, the cholesterol 7ahydroxylase, in human liver. The assay is based on isotope dilution-mass spectrometry, and endogenous microsomal cholesterol is used as the only substrate for the enzyme. Operative liver biopsies were obtained from patients undergoing elective cholecystectomy under highly standardi...
متن کاملBile acid synthesis in man: assay of hepatic microsomal cholesterol 7 alpha-hydroxylase activity by isotope dilution-mass spectrometry.
The present work describes an accurate assay of the rate-limiting enzyme in bile acid synthesis, the cholesterol 7 alpha-hydroxylase, in human liver. The assay is based on isotope dilution-mass spectrometry, and endogenous microsomal cholesterol is used as the only substrate for the enzyme. Operative liver biopsies were obtained from patients undergoing elective cholecystectomy under highly sta...
متن کاملCholesterol 7 -hydroxylase in rat liver microsomal preparations.
Subcellular fractions containing microsomes prepared from rat livers homogenized in the absence of EDTA catalysed the oxidation of cholesterol to 7alpha-hydroxycholesterol, 7-oxocholesterol, 7beta-hydroxycholesterol and 5alpha-cholestane-3beta,5,6beta-triol. These reactions required native protein, molecular oxygen and NADPH. It is suggested that these compounds are formed by a peroxidation ana...
متن کاملA Sensitive Double-Isotope Derivative Assay
A sensitive and specific double-isotope dilution method for assaying norepinephrine and epinephrine separately is described. The method is based on enzymatic conversion of these two catecholamines to their respective metanephrines and was applied successfully to measurement of resting plasma concentrations of norepinephrine and epinephrine in normal subjects with the finding that norepinephrine...
متن کاملRegulation of bile acid synthesis. Measurement of cholesterol 7 alpha-hydroxylase activity in rat liver microsomal preparations in the absence of endogenous cholesterol.
A rapid procedure was developed to measure hepatic cholesterol 7 alpha-hydroxylase activity in the absence of endogenous microsomal cholesterol. This method involves the preparation of an acetone powder from the microsomal fraction of rat liver that retains its cholesterol 7 alpha-hydroxylase activity and contains virtually no endogenous cholesterol. The enzyme activity is measured in the prese...
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ژورنال
عنوان ژورنال: Journal of Lipid Research
سال: 1975
ISSN: 0022-2275
DOI: 10.1016/s0022-2275(20)36733-x