Biomaterial Database

Characterization of the reaction of GDP-mannose with dolichol phosphate in liver membranes. 1975

D A Vessey, and D Zakim

The Mn-2+ dependent mannosyl transfer reaction between GDP-[14-C]mannose and dolichol phosphate, which is catalyzed by liver membranes, could not be followed accurately with the existing assay systems. Thus, GDP-[14-C]mannose is hydrolyzed rapidly by a pyrophosphatase present in microsomal and Golgi fractions from liver cells. The rate of the hydrolysis is rapid enough to limit the extent of incorporation of [14-c]mannose into endogenous acceptors. AMP was an effective inhibitor of the pyrophosphatase in Golgi membranes, and protected GDP-mannose from metabolism in alternative pathways. In the presence of AMP it was possible accurately to follow the time course of synthesis of dolichol phosphate [14-c]mannose over short time periods. Even though the time course of the reaction was measured over 2 s intervals, no linear portion could be detected in plots of product formed versus time. The kinetics of synthesis did, however, fit an equation for a first-order kinetic process. The basis for the first-order kinetics seems related to the very small amounts of dolichol phosphate in membranes. The values of the first-order rate constant is dependent on the concentrations of GDP-mannose and Mn-2+ added to the assays.

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
D008345	Manganese	A trace element with atomic symbol Mn, atomic number 25, and atomic weight 54.94. It is concentrated in cell mitochondria, mostly in the pituitary gland, liver, pancreas, kidney, and bone, influences the synthesis of mucopolysaccharides, stimulates hepatic synthesis of cholesterol and fatty acids, and is a cofactor in many enzymes, including arginase and alkaline phosphatase in the liver. (From AMA Drug Evaluations Annual 1992, p2035)
D008433	Mathematics	The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Mathematic
D009702	Nucleoside Diphosphate Sugars		Diphosphate Sugars, Nucleoside,Sugars, Nucleoside Diphosphate
D009943	Organophosphorus Compounds	Organic compounds that contain phosphorus as an integral part of the molecule. Included under this heading is broad array of synthetic compounds that are used as PESTICIDES and DRUGS.	Organophosphorus Compound,Organopyrophosphorus Compound,Organopyrophosphorus Compounds,Compound, Organophosphorus,Compound, Organopyrophosphorus,Compounds, Organophosphorus,Compounds, Organopyrophosphorus
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
D004224	Diterpenes	Twenty-carbon compounds derived from MEVALONIC ACID or deoxyxylulose phosphate.	Diterpene,Diterpenes, Cembrane,Diterpenes, Labdane,Diterpenoid,Labdane Diterpene,Norditerpene,Norditerpenes,Norditerpenoid,Cembranes,Diterpenoids,Labdanes,Norditerpenoids,Cembrane Diterpenes,Diterpene, Labdane,Labdane Diterpenes
D004286	Dolichols	A class of polyprenols which contain approximately 20 isoprene residues. Although considered ISOPRENOIDS, they terminate with an alpha-saturated isoprenoid group at the hydroxy end of the molecule.	6,10,14,18,22,26,30,34,38,42,46,50,54,58,62,66,70,74,78-Octacontanonadecaen-1-ol, 3,7,11,15,19,23,27,31,35,39,43,47,51,55,59,63,67,71,75,79-eicosamethyl-,Dolichol,Eicosamethyl Octacontanonadecasen-1-ol,Eicosamethyl Octacontanonadecasen 1 ol,Octacontanonadecasen-1-ol, Eicosamethyl
D006155	Guanosine Diphosphate Mannose	A nucleoside diphosphate sugar which can be converted to the deoxy sugar GDPfucose, which provides fucose for lipopolysaccharides of bacterial cell walls. Also acts as mannose donor for glycolipid synthesis.	GDP Mannose,Guanosine Diphosphomannose,Guanosine Pyrophosphate Mannose,Diphosphate Mannose, Guanosine,Diphosphomannose, Guanosine,Mannose, GDP,Mannose, Guanosine Diphosphate,Mannose, Guanosine Pyrophosphate,Pyrophosphate Mannose, Guanosine