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At least 667 records · Page 37Linked to original sources
PubMed1975

Pyruvate kinase deficiency anemia with terminal myelofibrosis and osteosclerosis in a beagle.

A 15-month-old male Beagle with chronic hemolytic anemia was found to have erythrocytic pyruvate kinase deficiency and, terminally, myelofibrosis and osteosclerosis. The dog's erythron was studied by procedures that enabled close comparison with congenital hemolytic anemia (pyruvate kinase deficiency) of Basenji dogs. The affected dog's sire, dam, and one littermate--each clinically and hematologically normal--were found to have 50% reduction in erythrocytic pyruvate kinase (PK) activity.

Ancylostomiasis↗
PubMed2003

The dual activity of pyruvate kinase type M2 from chromatin extracts of neoplastic cells.

Pyruvate kinase type M(2) from Morris hepatoma 7777 tumour cell nuclei and cytosol, in contrast to types L and M(2) from nuclei and cytosol of normal rat liver, shows the histone H(1) kinase activity. Moreover, in the presence of L-cysteine and without ADP it converts 2-phosphoenolpyruvate (PEP) to pyruvate while in the presence of L-arginine or L-histidine does not. L-Cysteine markedly stimulates the activity of histone H(1) kinase transferring a phosphate group from PEP to, as results suggested, the epsilon -amino group of L-lysine of histone H(1). This, L-cysteine which is known to inhibit the activity of pyruvate kinase type M(2) from neoplastic cells transfering a phosphate from PEP to ADP, can act as a control factor champing the direction of enzymatic reaction in cancer cells.

Adenosine Triphosphate↗
PubMed1983

An essential role of cytosolic thioltransferase in protection of pyruvate kinase from rabbit liver against oxidative inactivation.

Pyruvate kinase from rabbit liver is inactivated spontaneously in the presence of air. Glutathione in physiological concentrations gives partial protection against inactivation. Full protection is obtained with glutathione and purified cytosolic thioltransferase supplemented with a glutathione-regenerating system. It is suggested that thioltransferase plus glutathione serve a general function in protecting protein thiol groups against oxidation.

Animals↗
PubMed1976

Atypical intraerythrocytic pyruvate kinase in some haematological diseases.

An atypical pyruvate kinase (PK) in erythrocytes was studied in a family with several different haematological diseases: non-spherocytic haemolysis, thrombocytopenia, myelofibrosis and polycythaemic traits. Atypical intraerythrocytic PK was also found in a group of non-related patients with myelofibrosis and polycythaemia vera. The atypical PK was characterised by abnormal urea inhibition and other relevant biochemical parameters.

Aged↗
PubMed2000

Pyruvate kinase from the thermophilic eubacterium Bacillus acidocaldarius as probe to monitor the sodium concentrations in the blood.

We describe the isolation and characterization of a pyruvate kinase from the thermophilic eubacterium Bacillus acidocaldarius. This protein appears to be a tetramer composed of four 55-kDa subunits. The intrinsic tryptophan fluorescence of this protein is quenched by approximately 20% upon binding sodium, which occurs with a dissociation constant near 15 mM. Importantly, the intrinsic fluorescence of this pyruvate kinase does not appear to be affected by potassium, magnesium, and calcium at the concentrations found in whole blood. It appears that this pyruvate kinase can provide the basis for a selective protein sensor for sodium with minimal interference from other cations.

Ammonium Sulfate↗
PubMed1984

Red cell pyruvate kinase in acute leukemia.

The red cell pyruvate kinase (PK) activity, KM for phosphoenolpyruvate (PEP) and adenosine diphosphate (ADP), and thermostability properties were studied in patients with acute leukemias. The acquired PK defect was found in patients with acute myeloid leukemia, while it was normal in acute non-myeloid leukemia enzyme kinetic tests. PK abnormality was expressed in 17 patients as deficient PK activity, in 15 patients as decreased enzyme thermostability, and in 11 patients as altered PK affinity for ADP.

Acute Disease↗
PubMed1988

A rapid purification procedure for pyruvate kinase from the hyphal fungus Aspergillus nidulans.

Pyruvate kinase was purified from the filamentous fungus Aspergillus nidulans with a 45-55% yield. The procedure involved dye-affinity chromatography and fast protein liquid chromatography, resulting in highly active and pure enzyme in milligram quantities within 2 days. The purified enzyme, a tetramer with a subunit molecular weight of 65,000 and an isoelectric point of 4.7, was used to determine the amino acid composition.

Amino Acids↗
PubMed1976

Dual divalent cation requirement for activation of pyruvate kinase; essential roles of both enzyme- and nucleotide-bound metal ions.

Rabbit muscle pyruvate kinase requires two divalent cations per active site for catalysis of the enolization of pyruvate in the presence of adenosine 5'-triphosphate (ATP). One divalent cation is bound directly to the enzyme and forms a second sphere complex with the bound ATP (site 1). The second divalent cation is directly coordinated to the phosphoryl groups of ATP and does not interact with the enzyme (site 2). The essential role of the divalent cation at site 1 is shown by the requirement for Mg2+ or Mn2+ for the enolization of pyruvate in the presence of the substitution inert Cr3+-ATP complex. The rate of detritiation of pyruvate shows a hyperbolic dependence of Mn2+ concentration in the presence of high concentrations of enzyme and Cr3+-ATP. A dissociation constant for Mn2+ from the pyruvate kinase-Mn2+-ATP-Cr3+-pyruvate complex of 1.3 +/- 0.5 muM is determined by the kinetics of detritiation of pyruvate and by parallel Mn2+ binding studies using electron paramagnetic resonance. The essential role of the divalent cation at site 2 is shown by the sigmoidal dependence of the rate of detritiation of pyruvate on Mn2+ concentration in the presence of high concentrations of enzyme and ATP yielding a dissociation constant of 29 +/- 9 muM for Mn2+ from site 2. This value is similar to the dissociation constant of the binary Mn-ATP complex (14 +/- 6 muM) determined under similar conditions. The rate of detritiation of pyruvate is proportional to the concentration of the pyruvate kinase-Mn2+-ATP-Mn2+-pyruvate complex, as determined by parellel kinetic and binding studies. Variation of the nature of the divalent cation at site 1 in the presence of CrATP causes only a twofold change in the rate of detritiation of pyruvate which does not correlate with the pKa of the metal-bound water. Variation of the nature of the divalent cation at both sites in the presence of ATP causes a sevenfold variation in the rate of detritiation or pyruvate that correlates with the pKa of the metal-bound water. The greater rate of enolization observed with CrATP fits this correlation, indicating that the electrophilicity of the nucleotide bound metal (at site 2) determines the rate of enolization of pyruvate.

Adenosine Triphosphate↗
PubMed1976

Molecular alterations in congenital erythrocyte pyruvate kinase deficiencies.

The molecular heterogeneity of congenital pyruvate kinase deficiencies becomes apparent from the results of immunological studies. In one case, a quantitative defect is plausible; in the second case, the most likely hypothesis is a molecular alteration of the binding site for the activator, with preservation of the antigenic specificity; in the third case an abnormal protein, extremely unstable and devoid of antigenic reactivity, carries catalytic activity. In no case can any cross-reacting material be detected.

Anemia, Hemolytic, Congenital↗
PubMed1984

Photo-oxidation of histidine residues in rat M1- and L-type pyruvate kinases.

Rat M1- and L-type pyruvate kinases were inactivated by photo-oxidation mediated by methylene blue at pH 8.0 and O degrees C according to first-order kinetics. The pH profiles of the inactivation rates of these isozymes showed that amino acid residues having a pK value of 7.0-7.5 were involved in the inactivation. Three histidine residues per subunit of M1- or L-type enzyme were destroyed by the photo-oxidation with complete loss of the enzyme activities. However, two of the three photo-oxidized histidine residues in the L-type enzyme were more important in the inactivation reaction. The kinetics of the partially inactivated L-type enzyme suggests that complete inactivation is achieved via an intermediate form having low affinity for phosphoenolpyruvate (PEP). These observations revealed the involvement of essential histidine residues of two different kinds in the catalytic mechanism of the L-type enzyme. In the photo-oxidation of M1-type enzyme, no intermediate form was observed. Addition of PEP or pyruvate to the reaction mixture markedly prevented the photo-oxidative inactivation of only the M1-type enzyme in the presence of K+ and Mg2+; the addition of ADP or ATP was ineffective even in the presence of both metal ions. This protective effect of PEP was counteracted by further addition of ATP but not by ADP. However, photo-oxidative inactivation of the L-type enzyme was not prevented even by the addition of PEP in the presence of both metal ions, owing to the low affinity for PEP at 0 degrees C, in spite of the presence of fructose 1,6-bisphosphate (Fru-1,6-P2).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Purification and properties of pyruvate kinase type M1 from bovine brain.

1. Pyruvate kinase type M1 was purified from bovine brain about 241-fold with 38% yield. 2. Specific activity of the enzyme was above 217 U/mg of protein (25 degrees C), relative mol. wt of the subunit--57,000 (+/- 2000) and pH optimum--6.8-7.2. 3. The enzyme shoved hyperbolic kinetics with Km value for PEP of 0.04 mM and for ADP of 0.3 mM. 4. Inorganic phosphate and ATP at concentrations below 4 mM showed activating effect, 1-phenylalanine and ATP above 6 mM--an inhibiting effect on the enzyme. 5. Inhibition by 1-phenylalanine was prevented by fructose-1,6-bisphosphate.

Animals↗
PubMed1986

The regulatory properties of yeast pyruvate kinase. Effect of pH.

The kinetics of pyruvate kinase from Saccharomyces cerevisiae were studied at 25 degrees C as a function of the concentrations of the substrates ADP, phosphoenolpyruvate and Mg2+ and the effector H+ in the pH range 5-6.6. The enzyme was activated by 100 mM-K+ and 32 mM-NH4+ throughout. It was found that the data could be described by the exponential model for a regulatory enzyme. On that basis, it was concluded that the binding of H+ is positively interactive and that the protonated enzyme is catalytically inactive. It was also found that H+ interacts positively with phosphoenolpyruvate but negatively with both ADP and Mg2+.

Adenosine Diphosphate↗
PubMed1995

Identification and functional characterization of an erythroid-specific enhancer in the L-type pyruvate kinase gene.

The rat L-type pyruvate kinase gene is transcribed either from promoter L in the liver or promoter L' in erythroid cells. We have now cloned and functionally characterized an erythroid-specific enhancer, mapped in the fetal liver as hypersensitive site B (HSSB) at 3.7 kilobases upstream from the promoter L'. Protein-DNA interactions were examined in the 200-base pair core of the site by in vivo footprinting experiments. In the fetal liver, footprints were revealed at multiple GATA and CACC/GT motifs, whose association is the hallmark of erythroid-specific regulatory sequences. Functional analysis of the HSSB element in transgenic mice revealed properties of a cell-restricted enhancer. Indeed, this element was able to activate the linked ubiquitous herpes simplex virus thymidine kinase promoter in erythroid tissues. The activation was also observed in a variety of nonerythroid tissues known to synthesize GATA-binding factors. In the context of L'-PK transgenes, HSSB was not needed for an erythroid-specific activation of the L' promoter, while it was required to stimulate the L' promoter activity to a proper level. Finally, HSSB cannot be replaced by strong ubiquitous viral or cellular enhancers, suggesting a preferential interaction of the HSSB region with the L' promoter.

Animals↗
PubMedDate not supplied

[Native and desensitized forms of L-type pyruvate kinase from rabbit kidney cortex].

A time-consuming procedure of isolation of pyruvate kinase isoenzymes from rabbit kidney cortex (more than 5 hrs) at 0-2 degrees led to obtaining of a desensitized form of "L" type, resembling the "M3" type of the enzyme from sceletal muscle. Rapid isolation of pyruvate kinase "L" type (within about 2.5 hrs) at 4-6 degrees provided the isoenzyme in the active (allosteric) form.

Allosteric Site↗
PubMed1997

Purification and characterization of a thermostable pyruvate kinase from the actinomycete Microbispora thermodiastatica.

The pyruvate kinase of Microbispora thermodiastatica was purified to homogeneity and some properties of the enzyme were characterized. The molecular weight of the enzyme by gel filtration is 277,000. The subunit molecular weight is 55,000 by SDS-polyacrylamide gel electrophoresis, and only one N-terminal amino acid sequence was obtained. It had a pH optimum around pH 4.5 to 7.0 and was stable over the range of pH 4.0-8.0. The enzyme is thermostable and no activity was lost after heat treatment at 55 degrees C for 60 min. AMP activated this enzyme and the saturation curve of the enzyme for PEP changed from sigmoidal type to hyperbolic type in the presence of AMP.

Actinomycetales↗
PubMed1990

Correlation between red cell pyruvate kinase activity and haematological parameters.

Red cell pyruvate kinase (PK) activity was correlated with haematological parameters. A statistically significant negative correlation was obtained between the activity of PK and total haemoglobin, total red blood cell count, and packed cell volume, and a positive correlation with white blood cell count, reticulocyte count, and red cell indices in anaemic patients. In non-anaemic patients the correlation between PK and haematological parameters was similar except with reticulocytes, where a slightly negative, statistically non-significant correlation was obtained. It is suggested that in patients with anaemias, infections, and leucocytosis, the elevation in PK level will significantly mask PK deficiency due to associated PK deficient variants. It is therefore essential to eliminate white cells before conducting PK assays, and to make corrections for reticulocytes.

Anemia↗
PubMed1986

Kinetic properties of liver pyruvate kinase from the flounder (Platichthys flesus L.).

Pyruvate kinase, purified from flounder liver, in two forms, i.e. PK I and PK II, is characterized by sigmoid kinetics with phosphoenolpyruvate as substrate at pH 6.3, 6.7 and 7.7. K0.5 for PEP increases with increasing pH. PK I and PK II show hyperbolic kinetics with ADP, but are inhibited by ADP concentrations above 1-2 mM. K0.5 for ADP decreases with increasing pH. PK I and PK II differ in their K0.5 values for PEP with a factor of at least 2, showing the highest figures for the latter. K0.5 for ADP is about the same for the two enzyme forms. Other nucleotide diphosphates can replace ADP as the substrate. When the nucleoside diphosphates are arranged in a rank order showing decreasing effectiveness as substrate, different rank orders are obtained for PK I and PK II.

Adenosine Diphosphate↗