title: Ca(2+)-stimulated organic pyrophosphatase--a new plant phosphohydrolase from wheat seedling microsomes.
abstract: A new kind of phosphohydrolase, an organic pyrophosphatase (OPPase) was found in microsomes of wheat seedlings. The enzyme was isolated from microsomal membranes with 350 mM KI and separated on Red Sepharose CL 6B into two fractions: OPPase I and OPPase II. OPPase II was partially purified and its physicochemical properties were characterized. The enzyme was of low molecular mass (40 kDa), hydrolyzed pyrophosphoric bonds coupled to organic residues and was activated by divalent cations with a distinct preference for Ca2+. Its activity was insensitive to commonly used inhibitors of all known plant ATPases and acid phosphatases. Some properties of the enzyme are similar to those of potato apyrase (EC 3.6.1.5).
authors.affiliation: Department of Biochemistry, Nicolaus Copernicus University, Toruń, Poland.
authors.forename: M A
authors.initials: MA
authors.lastname: Komoszyński
authors.forename: E
authors.initials: E
authors.lastname: Skalska
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology*; D002462:Cell Membrane / Q000201:enzymology; D005591:Chemical Fractionation; D002846:Chromatography, Affinity; D004789:Enzyme Activation; D007700:Kinetics; D008861:Microsomes / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D011755:Pyrophosphatases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D013379:Substrate Specificity; D014908:Triticum / Q000201:enzymology*
chemical_list: D000255:Adenosine Triphosphate; D011755:Pyrophosphatases; D002118:Calcium