scholarly journals Glycolate kinase activity in human red cells

Blood ◽  
1985 ◽  
Vol 65 (2) ◽  
pp. 480-483 ◽  
Author(s):  
S Fujii ◽  
E Beutler

Abstract Human red cells manifest glycolate kinase activity. This activity copurifies with pyruvate kinase and is decreased in the red cells of subjects with hereditary pyruvate kinase deficiency. Glycolate kinase activity was detected in the presence of FDP or glucose-1,6-P2. In the presence of 1 mmol/L FDP, the Km for adenosine triphosphate (ATP) was 0.28 mmol/L and a half maximum velocity for glycolate was obtained at 40 mmol/L. The pH optimum of the reaction was over 10.5 With 10 mumol/L FDP, 500 mumol/L glucose-1,6-P2, 2 mmol/L ATP, 5 mmol/L MgCl2, and 50 mmol/L glycolate at pH 7.5, glycolate kinase activity was calculated to be approximately 0.0013 U/mL RBC. In view of this low activity even in the presence of massive amounts of glycolate, the glycolate kinase reaction cannot account for the maintenance of the reported phosphoglycolate level in human red cells.

Blood ◽  
1985 ◽  
Vol 65 (2) ◽  
pp. 480-483
Author(s):  
S Fujii ◽  
E Beutler

Human red cells manifest glycolate kinase activity. This activity copurifies with pyruvate kinase and is decreased in the red cells of subjects with hereditary pyruvate kinase deficiency. Glycolate kinase activity was detected in the presence of FDP or glucose-1,6-P2. In the presence of 1 mmol/L FDP, the Km for adenosine triphosphate (ATP) was 0.28 mmol/L and a half maximum velocity for glycolate was obtained at 40 mmol/L. The pH optimum of the reaction was over 10.5 With 10 mumol/L FDP, 500 mumol/L glucose-1,6-P2, 2 mmol/L ATP, 5 mmol/L MgCl2, and 50 mmol/L glycolate at pH 7.5, glycolate kinase activity was calculated to be approximately 0.0013 U/mL RBC. In view of this low activity even in the presence of massive amounts of glycolate, the glycolate kinase reaction cannot account for the maintenance of the reported phosphoglycolate level in human red cells.


Blood ◽  
1987 ◽  
Vol 70 (4) ◽  
pp. 1211-1213 ◽  
Author(s):  
S Fujii ◽  
M Matsuda ◽  
S Okuya ◽  
Y Yoshizaki ◽  
Y Miura-Kora ◽  
...  

Abstract The hemolysate partially purified from human red cells was demonstrated to be capable of synthesizing fructose-2,6-bisphosphate (F-2,6-P2) from fructose-6-phosphate in the presence of adenosine triphosphate (ATP) indicating that human red cells contain fructose-6-phosphate,2-kinase. The effect of F-2,6-P2 on the rate-limiting enzymes of glycolysis, ie, hexokinase, phosphofructokinase (PFK), and pyruvate kinase, has also been examined. PFK was activated by this metabolite and the half- maximum activation was obtained at a concentration of 10(-7) mol/L. Neither hexokinase nor pyruvate kinase was affected by F-2,6-P2. These results suggest that human erythrocytes may contain this metabolite as one of the positive effectors for PFK.


Blood ◽  
1987 ◽  
Vol 70 (4) ◽  
pp. 1211-1213
Author(s):  
S Fujii ◽  
M Matsuda ◽  
S Okuya ◽  
Y Yoshizaki ◽  
Y Miura-Kora ◽  
...  

The hemolysate partially purified from human red cells was demonstrated to be capable of synthesizing fructose-2,6-bisphosphate (F-2,6-P2) from fructose-6-phosphate in the presence of adenosine triphosphate (ATP) indicating that human red cells contain fructose-6-phosphate,2-kinase. The effect of F-2,6-P2 on the rate-limiting enzymes of glycolysis, ie, hexokinase, phosphofructokinase (PFK), and pyruvate kinase, has also been examined. PFK was activated by this metabolite and the half- maximum activation was obtained at a concentration of 10(-7) mol/L. Neither hexokinase nor pyruvate kinase was affected by F-2,6-P2. These results suggest that human erythrocytes may contain this metabolite as one of the positive effectors for PFK.


Blood ◽  
1988 ◽  
Vol 72 (2) ◽  
pp. 500-506 ◽  
Author(s):  
CR Zerez ◽  
MD Wong ◽  
NA Lachant ◽  
KR Tanaka

Abstract RBCs from patients with hemolytic anemia due to pyruvate kinase (PK) deficiency are characterized by a decreased total adenine and pyridine nucleotide content. Because phosphoribosylpyrophosphate (PRPP) is a precursor of both adenine and pyridine nucleotides, we investigated the ability of intact PK-deficient RBCs to accumulate PRPP. The rate of PRPP formation in normal RBCs (n = 11) was 2.89 +/- 0.80 nmol/min.mL RBCs. In contrast, the rate of PRPP formation in PK-deficient RBCs (n = 4) was markedly impaired at 1.03 +/- 0.39 nmol/min.mL RBCs. Impaired PRPP formation in these cells was not due to the higher proportion of reticulocytes. To study the mechanism of impaired PRPP formation, PK deficiency was simulated by incubating normal RBCs with fluoride. In normal RBCs, fluoride inhibited PRPP formation, caused adenosine triphosphate (ATP) depletion, prevented 2,3-diphosphoglycerate (DPG) depletion, and inhibited pentose phosphate shunt (PPS) activity. These results together with other data suggest that impaired PRPP formation is mediated by changes in ATP and DPG concentration, which lead to decreased PPS and perhaps decreased hexokinase and PRPP synthetase activities. Impaired PRPP formation may be a mechanism for the decreased adenine and pyridine nucleotide content in PK-deficient RBCs.


1970 ◽  
Vol 116 (5) ◽  
pp. 819-824 ◽  
Author(s):  
G. F. Cox ◽  
D. D. Davies

1. The effect of pH on the Vmax. and concentration of NAD+ at half-maximum velocity at a constant isocitrate concentration was examined, and the results were related to the requirements for binding of H+ ions to the enzyme. 2. The effect of varying the NAD+ concentration on the pH optimum with constant isocitrate concentration was studied. 3. A comparison has been made between the effect of isocitrate concentration on the characteristics of binding of NAD+ and the effect of NAD+ concentration on the characteristics of isocitrate binding at three different pH values. 4. The mechanistic and metabolic significance of these studies is considered.


2010 ◽  
Vol 23 (6) ◽  
pp. 479-484
Author(s):  
L. O. Medeiros ◽  
L. F. Medeiros ◽  
S. R. Barcelos ◽  
S. Ferri ◽  
U. R. Reiner

1968 ◽  
Vol 278 (2) ◽  
pp. 73-81 ◽  
Author(s):  
David G. Nathan ◽  
Frank A. Oski ◽  
Denis R. Miller ◽  
Frank H. Gardner

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2180-2180
Author(s):  
Charles Kung ◽  
Jeff Hixon ◽  
Penelope Kosinski ◽  
Gavin Histen ◽  
Collin Hill ◽  
...  

Abstract Pyruvate kinase deficiency (PKD) is an autosomal recessive enzymopathy that is the most common cause of hereditary nonspherocytic hemolytic anemia (HNSHA). PKD is a rare disease characterized by a life-long chronic hemolysis with severe co-morbidities. It is hypothesized that insufficient energy production to maintain red cell membrane homeostasis promotes the chronic hemolysis. Treatment is generally palliative, focusing on the resultant anemia, and there are no approved drugs that directly target mutated pyruvate kinase. Here, we describe the mechanism of action and cellular effects of AG-348, an allosteric activator of the red cell isoform of pyruvate kinase (PKR). Hundreds of mutant alleles of PKR have been identified and are known to have deleterious effects on catalytic activity, protein stability, or protein expression. We demonstrate that AG-348 can potently activate a spectrum of recombinantly expressed PKR mutant proteins, including mutations that span distinct subdomains of the enzyme. The R532W mutation is quite sensitive to AG-348 modulation, with over 4-fold activation of the enzyme activity, even as the mutation renders PKR insensitive to stimulation by its endogenous allosteric regulator fructose 1,6-bisphosphate (FBP) (Figure A). Crystallographic analysis reveals that very few mutations associated with PKD occur within the AG-348 binding pocket, accounting for its broad activity. The binding of AG-348 attenuates the thermostability defect of several mutant alleles of PKR, including the commonly observed R510Q mutant that has a half-life of ∼2% of the half-life of wild-type PKR when incubated at 53°C. Pre-incubation of the R510Q protein with AG-348 restores the half-life to ∼70% that of the wild-type enzyme (Figure B). PKD red cells are characterized by changes in metabolism associated with defective glycolysis, including a build-up of the PKR substrate phosphenolpyruvate (PEP) and deficiency in the PKR product adenosine triphosphate (ATP). PKD red cells from several patients with distinct compound heterozygous PKR mutations exposed to AG-348 had increased PKR enzyme activity (up to 4-fold over control) and showed consistent dose and time-dependent metabolic responses (Figure C), including sharp reductions in PEP (up to 70% compared to control) and increases in ATP levels (up to 100% over control). These responses were observed in patient samples harboring PKR mutations that we had studied biochemically (including R486W and R510Q), but also in an instance where the mutation had not previously been biochemically characterized (A495V). In these ex-vivo settings, ATP levels in AG-348 treated cells can reach levels that are typical of normal, non-PKD red cells. These data support the hypothesis that drug intervention with AG-348 may restore glycolytic pathway activity and normalize red cell metabolism in vivo. This therapeutic approach may be an effective way to correct the underlying pathology of PKD and, importantly, provide clinical benefit to patients. Disclosures: Kung: Agios Pharmaceuticals: Employment, Equity Ownership. Hixon:Agios Pharmaceuticals: Employment, Equity Ownership. Kosinski:Agios Pharmaceuticals: Employment, Equity Ownership. Histen:Agios Pharmaceuticals: Employment, Equity Ownership. Hill:Agios Pharmaceuticals: Employment, Equity Ownership. Si:Agios Pharmaceuticals: Employment, Equity Ownership. Kernytsky:Agios Pharmaceuticals: Employment, Equity Ownership. Chen:Agios Pharmaceuticals: Employment, Equity Ownership. DeLaBarre:Agios Pharmaceuticals: Employment, Equity Ownership. Clasquin:Agios Pharmaceuticals: Employment, Equity Ownership. Ho:Agios Pharmaceuticals: Employment, Equity Ownership. Salituro:Agios Pharmaceuticals: Employment, Equity Ownership. Popovici-Muller:Agios Pharmaceuticals: Employment, Equity Ownership. Agresta:Agios Pharmaceuticals: Employment, Equity Ownership. Silverman:Agios Pharmaceuticals: Employment, Equity Ownership. Dang:Agios Pharmaceuticals: Employment, Equity Ownership.


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