Biomaterial Database

Subcellular location and properties of rat renal 25-hydroxyvitamin D3-1 alpha-hydroxylase. 1985

S K Paulson, and H F DeLuca

The subcellular location and some properties of the rat kidney 25-hydroxyvitamin D3-1 alpha-hydroxylase are described. Enzyme activity can be measured as previously discussed (Tanaka, Y., and DeLuca, H.F. (1981) Proc. Natl. Acad. Sci. U. S. A. 78, 196-199) using saturating substrate (25-hydroxyvitamin D3) concentrations. The reaction is linear with time for up to 30 min at a substrate concentration of 80 microM and 9-11 mg/ml mitochondrial protein. The enzyme, located in the mitochondria, requires molecular oxygen and a source of NADPH. Succinate supplies NADPH for 1 alpha-hydroxylation through reversal of electron transport and transhydrogenation as shown by inhibition with antimycin A and dinitrophenol. Malate supplies NADPH for the reaction via the mitochondrial malic enzyme or malate dehydrogenase and transhydrogenase as indicated by the lack of inhibition by antimycin A but inhibition with dinitrophenol. Metyrapone and carbon monoxide both inhibit 1 alpha-hydroxylation indicating the involvement of cytochrome P-450. Diphenyl-p-phenylenediamine, a lipid peroxidase inhibitor, has no effect on 1 alpha-hydroxylation.

UI	MeSH Term	Description	Entries
D007668	Kidney	Body organ that filters blood for the secretion of URINE and that regulates ion concentrations.	Kidneys
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008293	Malates	Derivatives of malic acid (the structural formula: (COO-)2CH2CHOH), including its salts and esters.
D008297	Male		Males
D008928	Mitochondria	Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed)	Mitochondrial Contraction,Mitochondrion,Contraction, Mitochondrial,Contractions, Mitochondrial,Mitochondrial Contractions
D009249	NADP	Nicotinamide adenine dinucleotide phosphate. A coenzyme composed of ribosylnicotinamide 5'-phosphate (NMN) coupled by pyrophosphate linkage to the 5'-phosphate adenosine 2',5'-bisphosphate. It serves as an electron carrier in a number of reactions, being alternately oxidized (NADP+) and reduced (NADPH). (Dorland, 27th ed)	Coenzyme II,Nicotinamide-Adenine Dinucleotide Phosphate,Triphosphopyridine Nucleotide,NADPH,Dinucleotide Phosphate, Nicotinamide-Adenine,Nicotinamide Adenine Dinucleotide Phosphate,Nucleotide, Triphosphopyridine,Phosphate, Nicotinamide-Adenine Dinucleotide
D010100	Oxygen	An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.	Dioxygen,Oxygen-16,Oxygen 16
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013250	Steroid Hydroxylases	Cytochrome P-450 monooxygenases (MIXED FUNCTION OXYGENASES) that are important in steroid biosynthesis and metabolism.	Steroid Hydroxylase,Steroid Monooxygenases,Hydroxylase, Steroid,Hydroxylases, Steroid,Monooxygenases, Steroid
D015090	25-Hydroxyvitamin D3 1-alpha-Hydroxylase	A mitochondrial cytochrome P450 enzyme that catalyzes the 1-alpha-hydroxylation of 25-hydroxyvitamin D3 (also known as 25-hydroxycholecalciferol) in the presence of molecular oxygen and NADPH-FERRIHEMOPROTEIN REDUCTASE. This enzyme, encoded by CYP27B1 gene, converts 25-hydroxyvitamin D3 to 1-alpha,25-dihydroxyvitamin D3 which is the active form of VITAMIN D in regulating bone growth and calcium metabolism. This enzyme is also active on plant 25-hydroxyvitamin D2 (ergocalciferol).	25-Hydroxycholecalciferol 1-Hydroxylase,CYP27B1,Calcidiol 1-Monooxygenase,Cytochrome P-450 CYP27B1,25-Hydroxycholecalciferol-1-Hydroxylase,25-Hydroxyergocalciferol 1-alpha-Hydroxylase,25-Hydroxyvitamin D 1-alpha-Hydroxylase,25-Hydroxyvitamin D(3) 1 alpha-Hydroxylase,25-Hydroxyvitamin D2 1-hydroxylase,1-alpha-Hydroxylase, 25-Hydroxyergocalciferol,1-alpha-Hydroxylase, 25-Hydroxyvitamin D,1-hydroxylase, 25-Hydroxyvitamin D2,25 Hydroxycholecalciferol 1 Hydroxylase,25 Hydroxyergocalciferol 1 alpha Hydroxylase,25 Hydroxyvitamin D 1 alpha Hydroxylase,25 Hydroxyvitamin D2 1 hydroxylase,25 Hydroxyvitamin D3 1 alpha Hydroxylase,Calcidiol 1 Monooxygenase,Cytochrome P 450 CYP27B1