Kinetic properties of glucose-6-phosphate dehydrogenase from lamb kidney cortex

Biochimie ◽  
2005 ◽  
Vol 87 (2) ◽  
pp. 187-190 ◽  
Author(s):  
Nuray N. Ulusu ◽  
Berivan Tandogan ◽  
Ferhan E. Tezcan
Keyword(s):  
Kidney Cortex ◽  
Kinetic Properties ◽  
Glucose 6 Phosphate Dehydrogenase

scholarly journals Comparison of the kinetic properties of the pyruvate dehydrogenase complex from pig kidney cortex and medulla.

1993 ◽  
Vol 40 (3) ◽  
pp. 411-419 ◽  
Author(s):  
T Pawełczyk ◽  
M S Olson
Keyword(s):  
Ionic Strength ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Product Inhibition ◽  
Hill Coefficient ◽  
Kidney Cortex ◽  
Kinetic Properties ◽  
Kidney Medulla ◽  
Pig Kidney ◽  
Dehydrogenase Complex

The activity of the pyruvate dehydrogenase complex (PDC) purified from pig kidney medulla was affected by K+, Na+, Cl-, HCO3-, HPO4(2-) and changes in ionic strength. Increased ionic strength influenced the activity of PDC from medulla by decreasing the Vmax and S0.5 for pyruvate and increasing the Hill coefficient. The magnitude of these changes was smaller than the corresponding changes for PDC purified from the cortex. In the presence of K+ (80 mM), Na+ (20 mM), Cl- (20 mM), HCO3- (20 mM), HPO4(2-) (10 mM) and at ionic strength of 0.15 M the S0.5 for pyruvate of PDC from medulla was 117 microM and the enzyme complex was saturated by 1.1 mM pyruvate. Under these conditions the S0.5 for pyruvate of PDC derived from cortex was 159 microM and the enzyme was saturated at 4.5 mM pyruvate. Based on the results presented in this report it is suggested that PDC in kidney medulla may be regulated not only by a phosphorylation/dephosphorylation system and end-product inhibition but also via changes in ionic strength.

scholarly journals Glucose-6-Phosphate Dehydrogenase Regulation in Anoxia Tolerance of the Freshwater Crayfish Orconectes virilis

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Benjamin Lant ◽  
Kenneth B. Storey
Keyword(s):  
Protein Kinase ◽  
Antioxidant Defense ◽  
Pentose Phosphate ◽  
Kinetic Properties ◽  
Freshwater Crayfish ◽  
Orconectes Virilis ◽  
Rate Determining Step ◽  
Flow Through ◽  
Glucose 6 Phosphate Dehydrogenase

Glucose-6-phosphate dehydrogenase (G6PDH), the enzyme which catalyzes the rate determining step of the pentose phosphate pathway (PPP), controls the production of nucleotide precursor molecules (R5P) and powerful reducing molecules (NADPH) that support multiple biosynthetic functions, including antioxidant defense. G6PDH from hepatopancreas of the freshwater crayfish (Orconectes virilis) showed distinct kinetic changes in response to 20 h anoxic exposure. Km values for both substrates decreased significantly in anoxic crayfish; Km NADP+ dropped from 0.015±0.008 mM to 0.012±0.008 mM, and Km G6P decreased from 0.13±0.02 mM to 0.08±0.007 mM. Two lines of evidence indicate that the mechanism involved is reversible phosphorylation. In vitro incubations that stimulated protein kinase or protein phosphatase action mimicked the effects on anoxia on Km values, whereas DEAE-Sephadex chromatography showed the presence of two enzyme forms (low- and high-phosphate) whose proportions changed during anoxia. Incubation studies implicated protein kinase A and G in mediating the anoxia-responsive changes in G6PDH kinetic properties. In addition, the amount of G6PDH protein (measured by immunoblotting) increased by ∼60% in anoxic hepatopancreas. Anoxia-induced phosphorylation of G6PDH could contribute to modifying carbon flow through the PPP under anoxic conditions, potentially maintaining NADPH supply for antioxidant defense during prolonged anoxia-induced hypometabolism.

scholarly journals NHERF1 Loss Upregulates Enzymes of the Pentose Phosphate Pathway in Kidney Cortex

Antioxidants ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 862
Author(s):  
Adrienne Bushau-Sprinkle ◽  
Michelle T. Barati ◽  
Kenneth B. Gagnon ◽  
Syed Jalal Khundmiri ◽  
Kathleen Kitterman ◽  
...  
Keyword(s):  
Pentose Phosphate Pathway ◽  
Mitochondrial Protein ◽  
Pentose Phosphate ◽  
Metabolic Enzyme ◽  
Kidney Cortex ◽  
Mitochondrial Morphology ◽  
Proximal Tubule Cells ◽  
Cisplatin Nephrotoxicity ◽  
Increased Sensitivity ◽  
Glucose 6 Phosphate Dehydrogenase

(1) Background: We previously showed Na/H exchange regulatory factor 1 (NHERF1) loss resulted in increased susceptibility to cisplatin nephrotoxicity. NHERF1-deficient cultured proximal tubule cells and proximal tubules from NHERF1 knockout (KO) mice exhibit altered mitochondrial protein expression and poor survival. We hypothesized that NHERF1 loss results in changes in metabolic pathways and/or mitochondrial dysfunction, leading to increased sensitivity to cisplatin nephrotoxicity. (2) Methods: Two to 4-month-old male wildtype (WT) and KO mice were treated with vehicle or cisplatin (20 mg/kg dose IP). After 72 h, kidney cortex homogenates were utilized for metabolic enzyme activities. Non-treated kidneys were used to isolate mitochondria for mitochondrial respiration via the Seahorse XF24 analyzer. Non-treated kidneys were also used for LC-MS analysis to evaluate kidney ATP abundance, and electron microscopy (EM) was utilized to evaluate mitochondrial morphology and number. (3) Results: KO mouse kidneys exhibit significant increases in malic enzyme and glucose-6 phosphate dehydrogenase activity under baseline conditions but in no other gluconeogenic or glycolytic enzymes. NHERF1 loss does not decrease kidney ATP content. Mitochondrial morphology, number, and area appeared normal. Isolated mitochondria function was similar between WT and KO. Conclusions: KO kidneys experience a shift in metabolism to the pentose phosphate pathway, which may sensitize them to the oxidative stress imposed by cisplatin.

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