Biomaterial Database

Epimerization of the 7-hydroxy group of bile acids by the combination of two kinds of microorganisms with 7 alpha- and 7 beta-hydroxysteroid dehydrogenase activity, respectively. 1981

S Hirano, and N Masuda

An unidentified gram-positive anaeroic organism capable of dehydrogenating the 7 beta-hydroxy group of ursodeoxycholic acid was recovered from human feces. By combined action of this organism with the ordinary 7 alpha-dehydrogenating bacteria, chenodeoxycholic acid and cholic acid alike were readily converted into their respective 7 beta-epimers and the reverse reactions were also carried out. The estimated levels of these 7 alpha- and 7 beta-dehydrogenating organisms among the intestinal microflora give a satisfactory explanation for the frequent appearance of the 7 beta-hydroxylated bile acids in vivo.

UI	MeSH Term	Description	Entries
D007536	Isomerism	The phenomenon whereby certain chemical compounds have structures that are different although the compounds possess the same elemental composition. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)	Isomerisms
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D006913	Hydroxysteroid Dehydrogenases	Enzymes of the oxidoreductase class that catalyze the dehydrogenation of hydroxysteroids. (From Enzyme Nomenclature, 1992) EC 1.1.-.	Hydroxysteroid Dehydrogenase,Dehydrogenase, Hydroxysteroid,Dehydrogenases, Hydroxysteroid
D000693	Anaerobiosis	The complete absence, or (loosely) the paucity, of gaseous or dissolved elemental oxygen in a given place or environment. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)	Anaerobic Metabolism,Anaerobic Metabolisms,Anaerobioses,Metabolism, Anaerobic,Metabolisms, Anaerobic
D001419	Bacteria	One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.	Eubacteria
D001647	Bile Acids and Salts	Steroid acids and salts. The primary bile acids are derived from cholesterol in the liver and usually conjugated with glycine or taurine. The secondary bile acids are further modified by bacteria in the intestine. They play an important role in the digestion and absorption of fat. They have also been used pharmacologically, especially in the treatment of gallstones.	Bile Acid,Bile Salt,Bile Salts,Bile Acids,Acid, Bile,Acids, Bile,Salt, Bile,Salts, Bile