Phosphoprotein phosphatase of bovine spleen cell nuclei: physicochemical properties
The physicochemical properties of phosphoprotein phosphatase (EC 1.3.1.16) from bovine spleen cell nuclei were studied. The enzyme possesses broad substrate specificity and catalyzes the dephosphorylation of phosphocasein, ATP, ADP, and p-nitrophenyl phosphate (pNPP). K/sub m/ for ATP, ADP, and pNPP are equal to 0.44, 0.43, and 1.25 mM, respectively. M/sub r/ of the enzyme, according to the data of gel filtraction of Sephadex G-75 and electrophoresis in polyacrylamide gel of various concentrations is approx. 33,000. In electrophoresis in the presence of SDS, two protein bands with M/sub r/ 12,000 and 18,000 are detected. In the enzyme molecule, acid amino acid residues predominate; two free SH groups and two disulfide bridges are detected. Phosphoprotein phosphatase is a glycoprotein, containing approx. 22% carbonhydrates. The protein possesses a supplementary absorption maximum at 560 nm. Ammonium molybdate is a competitive inhibitor with K/sub i/ 0.37 ..mu..M, while sodium fluoride is a noncompetitive inhibitor with K/sub i/ 1.3 mM. Incubation in the presence of 2 mM phenylmethylsulfonyl fluoride for 25 h leads to a loss of approx. 46% of the enzymatic activity. Ammonium molybdate, sodium fluoride, and PMSF are reversible inhibitors. Modifications of the SH groups, NH/sub 2/ groups, and histidine leads to a decrease in the enzymatic activity. Incubation of phosphoprotein phosphatase with (..gamma..-/sup 32/P)ATP leads to the incorporation of 0.33 mole /sup 33/P per mole of the enzyme. The mechanism of hydrolysis of the phosphodiester bond, catalyzed by the enzyme, is discussed.
- Research Organization:
- A.A. Zhdanov Leningrad State Univ., USSR
- OSTI ID:
- 5933374
- Journal Information:
- Biochemistry (Engl. Transl.); (United States), Vol. 50:7; Other Information: Translation from Biokhimiya; 50: No. 7, 1067-1075(Jul 1985)
- Country of Publication:
- United States
- Language:
- English
Similar Records
Co-purification of dihydrofolate synthetase and N/sub 10/formyltetrahydropteroyldiglutamate synthetase from E. coli
Identification, purification, and characterization of phosphotyrosine-specific protein phosphatases from cultured chicken embryo fibroblasts
Related Subjects
CELL NUCLEI
RADIOENZYMATIC ASSAY
PHOSPHATASES
CATALYTIC EFFECTS
ENZYME ACTIVITY
SPLEEN CELLS
ADP
AMMONIUM COMPOUNDS
ATP
BIOLOGICAL EFFECTS
CASEIN
CATTLE
ELECTROPHORESIS
ENZYMATIC HYDROLYSIS
ENZYME INHIBITORS
LABELLED COMPOUNDS
MOLYBDATES
PHOSPHORUS 32
PROTEINS
SODIUM FLUORIDES
SUBSTRATES
ALKALI METAL COMPOUNDS
ANIMAL CELLS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CELL CONSTITUENTS
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
DECOMPOSITION
DOMESTIC ANIMALS
ENZYMES
ESTERASES
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
HYDROLASES
HYDROLYSIS
ISOTOPES
LIGHT NUCLEI
LYSIS
MAMMALS
MOLYBDENUM COMPOUNDS
NUCLEI
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
OXYGEN COMPOUNDS
PHOSPHORUS ISOTOPES
RADIOISOTOPES
REFRACTORY METAL COMPOUNDS
RUMINANTS
SODIUM COMPOUNDS
SOLVOLYSIS
SOMATIC CELLS
TRANSITION ELEMENT COMPOUNDS
VERTEBRATES
550301* - Cytology- Tracer Techniques
550201 - Biochemistry- Tracer Techniques