Biomaterial Database

A calcium ion-dependent atp pyrophosphohydrolase in Physarum polycephalum. 1975

M Kawamura, and K Nagano

An activity of ATP Pyrophosphohydrolase (EC 3.6.1.8) was found in the soluble fraction of the plasmodium of Physarum polycephalum. The products of the enzyme reaction were inorganic pyrophosphate and 5'-AMP in equimolar quantities. The enzyme had a pronounced requirement for Ca2+ with high specificity. Mg-2+ was not an essential cofactor but stimulated the enzyme activity about 2.5-fold of the control. The enzyme hydrolyzed ITP, GTP and beta,gamma-methylene ATP at a limited rate. Among inhibitors tested, 3 mM caffeine reduced the activity to about 75% of the control. The enzyme had a broad pH optimum around pH=7.0 and the Km for ATP was 2.0 mM. An Arrhenius plot showed a break at about 18 degrees C and the calculated activation energies were 6.7 and 11.4 kcal/mol above and below the transition temperature, respectively. Disc electrophoresis in dodecyl sulfate and gel filtration on Sephadex -g-200 gave apparent molecular weights of 56 000 and 240 000, respectively, suggesting that the native enzyme was built up from 4 polypeptide chains. The possible role of the enzyme in vivo was discussed.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008274	Magnesium	A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D009235	Myxomycetes	A division of organisms that exist vegetatively as complex mobile plasmodia, reproduce by means of spores, and have complex life cycles. They are now classed as protozoa but formerly were considered fungi.	Myxomycota,Protosteliomycetes,Slime Molds, Plasmodial,Slime Molds, True,Mold, Plasmodial Slime,Mold, True Slime,Molds, Plasmodial Slime,Molds, True Slime,Myxomycete,Myxomycotas,Plasmodial Slime Mold,Plasmodial Slime Molds,Protosteliomycete,Slime Mold, Plasmodial,Slime Mold, True,True Slime Mold,True Slime Molds
D010804	Physarum	A genus of protozoa, formerly also considered a fungus. Characteristics include the presence of violet to brown spores.	Physarums
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
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
D002110	Caffeine	A methylxanthine naturally occurring in some beverages and also used as a pharmacological agent. Caffeine's most notable pharmacological effect is as a central nervous system stimulant, increasing alertness and producing agitation. It also relaxes SMOOTH MUSCLE, stimulates CARDIAC MUSCLE, stimulates DIURESIS, and appears to be useful in the treatment of some types of headache. Several cellular actions of caffeine have been observed, but it is not entirely clear how each contributes to its pharmacological profile. Among the most important are inhibition of cyclic nucleotide PHOSPHODIESTERASES, antagonism of ADENOSINE RECEPTORS, and modulation of intracellular calcium handling.	1,3,7-Trimethylxanthine,Caffedrine,Coffeinum N,Coffeinum Purrum,Dexitac,Durvitan,No Doz,Percoffedrinol N,Percutaféine,Quick-Pep,Vivarin,Quick Pep,QuickPep
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D002850	Chromatography, Gel	Chromatography on non-ionic gels without regard to the mechanism of solute discrimination.	Chromatography, Exclusion,Chromatography, Gel Permeation,Chromatography, Molecular Sieve,Gel Filtration,Gel Filtration Chromatography,Chromatography, Size Exclusion,Exclusion Chromatography,Gel Chromatography,Gel Permeation Chromatography,Molecular Sieve Chromatography,Chromatography, Gel Filtration,Exclusion Chromatography, Size,Filtration Chromatography, Gel,Filtration, Gel,Sieve Chromatography, Molecular,Size Exclusion Chromatography