Biomaterial Database

Adenosine 5'-tetraphosphate phosphohydrolase activity is an inherent property of soluble exopolyphosphatase from yeast Saccharomyces cerevisiae. 1998

A Guranowski, and E Starzyńska, and L D Barnes, and A K Robinson, and S Liu

Katedra Biochemii i Biotechnologii, Akademia Rolnicza, ul. Wolyńska 35, 60-637 Poznań, Poland. guranow@au.poznan.pl

Homogeneous soluble exopolyphosphatase (EC 3.6.1.11) from yeast Saccharomyces cerevisiae, (scPPX1) behaves as an adenosine 5'-tetraphosphate phosphohydrolase (EC 3.6.1.14). The hydrolysis of adenosine 5'-tetraphosphate (p4A) to ATP and orthophosphate absolutely depends on one of the following cations: Co2+>Mn2+>Mg2+>Ni2+. Optimum pH is around 4.75 and the Km for p4A estimated at that pH in 50 mM sodium acetate and at 5 mM CoCl2 is 80+/-10 microM. Adenosine 5'-pentaphosphate (p5A) is degraded under these conditions 18-fold more slowly than p4A. Assuming that the mass of scPPX1 is 45 kDa, the calculated kcat values for p4A and for p5A are 723 and 40 s-1, respectively. Two other nucleoside 5'-tetraphosphates (p4N), guanosine tetraphosphate (p4G) and inosine tetraphosphate (p4I), were hydrolyzed to Pi and either GTP or ITP, respectively, at the same rate as that observed for the hydrolysis of p4A. Ammonium molybdate, sodium o-vanadate and zinc chloride inhibit the hydrolysis of p4A (I50 values are 0.08, 0.3 and 0.4 mM, respectively). This newly recognized 'acidic' adenosine tetraphosphatase activity from yeast is compared with two 'pH 8' adenosine tetraphosphatases described earlier in rabbit and yellow lupin.

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.
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)
D009532	Nickel	A trace element with the atomic symbol Ni, atomic number 28, and atomic weight 58.69. It is a cofactor of the enzyme UREASE.
D003035	Cobalt	A trace element that is a component of vitamin B12. It has the atomic symbol Co, atomic number 27, and atomic weight 58.93. It is used in nuclear weapons, alloys, and pigments. Deficiency in animals leads to anemia; its excess in humans can lead to erythrocytosis.	Cobalt-59,Cobalt 59
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
D004791	Enzyme Inhibitors	Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.	Enzyme Inhibitor,Inhibitor, Enzyme,Inhibitors, Enzyme
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D006868	Hydrolysis	The process of cleaving a chemical compound by the addition of a molecule of water.
D000227	Adenine Nucleotides		Adenine Nucleotide,Adenosine Phosphate,Adenosine Phosphates,Nucleotide, Adenine,Nucleotides, Adenine,Phosphate, Adenosine,Phosphates, Adenosine