Biomaterial Database

Studies on a Ca2+-dependent nucleoside triphosphate pyrophosphohydrolase in rat liver plasma membranes. 1979

C Torp-Pedersen, and H Flodgaard, and T Saermark

A membrane-bound Ca2+-dependent nucleoside triphosphate pyrophosphohydrolase was solubilized in deoxycholate, separated from inorganic pyrophosphatase, and partially characterized. The Km for a variety of substrates was determined. At 10(-4) M free Ca2+ (pH 8.0) the Km values for ATP and GTP were 0.32 and 2.2 microM, respectively. With ATP as substrate, Mg2+, Sr2+, and Ba2+ could only replace Ca2+ to a limited degree. Both purine and pyrimidine nucleoside triphosphates were hydrolyzed yielding PPi and mononucleotides and similarly AMP and formed from adenosine-(beta gamma-methylene)triphosphate. UDPglucose was hydrolyzed at the pyrophosphate bond. Tripolyphosphate and phosphoribosyl-1-pyrophosphate (P-rib-PP) were not hydrolyzed. Substrate competition experiments showed that GTP inhibited pyrophosphohydrolysis of ATP competitively. However, UDP glucase and adenosine-(beta gamma-methylene)triphosphate inhibited ATP pyrophosphohydrolysis in a non-linear manner. Adenosine-(beta gamma-methylene)triphosphate inhibited pyrophosphohydrolysis of UDPglucose non-competitively, whereas UDPglucose inhibition of adenosine-(beta gamma-methylene) triphosphate pyrophosphohydr-lysis was competitive. The molecular weight of ATP pyrophosphohydrolase was estimated at 120 000 and the pI at 5.1 Pyrophosphohydrolysis of adenosine-(beta gamma-methylene)triphosphate was studied in a number of rat organs. Nearly all activity could be sedimented at 50 000 X g. Very high activities were found in liver, kidney and small intestine, whereas low activities were found in brain and blood.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008099	Liver	A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.	Livers
D011755	Pyrophosphatases	A group of enzymes within the class EC 3.6.1.- that catalyze the hydrolysis of diphosphate bonds, chiefly in nucleoside di- and triphosphates. They may liberate either a mono- or diphosphate. EC 3.6.1.-.	Pyrophosphatase
D002413	Cations, Divalent	Positively charged atoms, radicals or groups of atoms with a valence of plus 2, which travel to the cathode or negative pole during electrolysis.	Divalent Cations
D002462	Cell Membrane	The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.	Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D004591	Electrophoresis, Polyacrylamide Gel	Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.	Polyacrylamide Gel Electrophoresis,SDS-PAGE,Sodium Dodecyl Sulfate-PAGE,Gel Electrophoresis, Polyacrylamide,SDS PAGE,Sodium Dodecyl Sulfate PAGE,Sodium Dodecyl Sulfate-PAGEs
D004789	Enzyme Activation	Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.	Activation, Enzyme,Activations, Enzyme,Enzyme Activations
D000255	Adenosine Triphosphate	An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.	ATP,Adenosine Triphosphate, Calcium Salt,Adenosine Triphosphate, Chromium Salt,Adenosine Triphosphate, Magnesium Salt,Adenosine Triphosphate, Manganese Salt,Adenylpyrophosphate,CaATP,CrATP,Manganese Adenosine Triphosphate,MgATP,MnATP,ATP-MgCl2,Adenosine Triphosphate, Chromium Ammonium Salt,Adenosine Triphosphate, Magnesium Chloride,Atriphos,Chromium Adenosine Triphosphate,Cr(H2O)4 ATP,Magnesium Adenosine Triphosphate,Striadyne,ATP MgCl2
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
D014532	Uridine Diphosphate Glucose	A key intermediate in carbohydrate metabolism. Serves as a precursor of glycogen, can be metabolized into UDPgalactose and UDPglucuronic acid which can then be incorporated into polysaccharides as galactose and glucuronic acid. Also serves as a precursor of sucrose lipopolysaccharides, and glycosphingolipids.	UDP Glucose,UDPG,Uridine Diphosphoglucose,Diphosphate Glucose, Uridine,Diphosphoglucose, Uridine,Glucose, UDP,Glucose, Uridine Diphosphate