Kinetics of hypotonic lysis of human erythrocytes

2014 ◽  
Vol 6 (5) ◽  
pp. 1377 ◽  
Author(s):  
Lucas Moreira Cunha ◽  
Morun Bernardino-Neto ◽  
Mario da Silva Garrote-Filho ◽  
Carla Braga Avelar ◽  
Mariana Vaini de Freitas ◽  
...  
Keyword(s):  
Human Erythrocytes ◽  
Hypotonic Lysis ◽  
Kinetics Of

scholarly journals Determination of the steady-state turnover rates of the metabolically active pools of phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate in human erythrocytes

1989 ◽  
Vol 259 (3) ◽  
pp. 893-896 ◽  
Author(s):  
C E King ◽  
P T Hawkins ◽  
L R Stephens ◽  
R H Michell
Keyword(s):  
Steady State ◽  
Rate Constants ◽  
Human Erythrocytes ◽  
Turnover Rates ◽  
Metabolic Fluxes ◽  
Metabolic Pool ◽  
Phosphatidylinositol 4 ◽  
Kinetics Of ◽  
Phosphate Groups

When intact human erythrocytes are incubated at metabolic steady state in a chloride-free medium containing [32P]Pi, there is rapid labelling of the gamma-phosphate of ATP, followed by a slower labelling of the monoester phosphate groups of phosphatidylinositol 4-phosphate (PtdIns4P) and phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] [King, Stephens, Hawkins, Guy & Michell (1987) Biochem. J. 244, 209-217]. We have analysed the early kinetics of the labelling of these phosphate groups, in order to determine: (a) the steady-state rates of the interconversions of phosphatidylinositol, PtdIns4P and PtdIns(4,5)P2; and (b) the fractions of the total cellular complement of PtdIns4P and PtdIns(4,5)P2 that participate in this steady-state turnover. The experimental data most closely fit a pattern of PtdIns4P and PtdIns(4,5)P2 turnover in which one-quarter of the total cellular complement of each lipid is in the metabolic pool that participates in rapid metabolic turnover, with rate constants of 0.028 min-1 for the interconversion of PtdIns and PtdIns4P, and of 0.010 min-1 for the PtdIns4P/PtdIns(4,5)P2 cycle. These rate constants represent metabolic fluxes of approx. 2.1 nmol of lipid/h per ml of packed erythrocytes between PtdIns and PtdIns4P and of approx. 5.7 nmol/h per ml of cells between PtdIns4P and PtdIns(4,5)P2.

Kinetics of uptake and deacetylation of N-acetylcysteine by human erythrocytes

2007 ◽  
Vol 39 (9) ◽  
pp. 1698-1706 ◽  
Author(s):  
Julia E. Raftos ◽  
Stephney Whillier ◽  
Bogdan E. Chapman ◽  
Philip W. Kuchel
Keyword(s):  
Human Erythrocytes ◽  
Kinetics Of Uptake ◽  
Kinetics Of

scholarly journals Direct Evidence for Catalase as the Predominant H2O2 -Removing Enzyme in Human Erythrocytes

Blood ◽  
1997 ◽  
Vol 90 (12) ◽  
pp. 4973-4978 ◽  
Author(s):  
Sebastian Mueller ◽  
Hans-Dieter Riedel ◽  
Wolfgang Stremmel
Keyword(s):  
Hydrogen Peroxide ◽  
Glutathione Peroxidase ◽  
Enzyme Inhibition ◽  
Direct Evidence ◽  
Human Erythrocytes ◽  
H2o2 Concentration ◽  
H2o2 Decomposition ◽  
Erythrocyte Catalase ◽  
Normal Human ◽  
Kinetics Of

Abstract Decomposition of hydrogen peroxide (H2O2 ) at physiological levels was studied in human erythrocytes by means of a recently developed sensitive H2O2 assay. The exponential decay of H2O2 in the presence of purified erythrocyte catalase was followed down to 10−9 mol/L H2O2 at pH 7.4. H2O2 decomposition by purified erythrocyte glutathione peroxidase (GPO) could be directly observed down to 10−7 mol/L H2O2 . No enzyme inhibition was observed at these low H2O2 concentrations. Catalase and GPO activities can be determined separately in a titrated mixture of purified enzymes, which simulates the conditions of H2O2 removal by the erythrocyte. Experiments with fresh human hemolysate allowed us to determine H2O2 decomposition by catalase and GPO using these enzymes in their original quantitative ratio. The different kinetics of these enzymes are shown: H2O2 decomposition by catalase depends linearly on H2O2 concentration, whereas that by GPO becomes saturated at concentrations above 10−6 mol/L H2O2 . Even at very low H2O2 concentrations GPO reaches only approximately 8% of the rate at which catalase simultaneously degrades H2O2 . These data indicate an almost exclusive role for catalase in the removal of H2O2 in normal human erythrocytes.

Kinetics of Cl-dependent K influx in human erythrocytes with and without external Na: effect of NEM

1985 ◽  
Vol 249 (5) ◽  
pp. C490-C496 ◽  
Author(s):  
D. Kaji ◽  
T. Kahn
Keyword(s):  
Human Erythrocytes ◽  
Independent Component ◽  
Kinetic Properties ◽  
Maximal Velocity ◽  
Na Effect ◽  
Low K ◽  
Kinetics Of ◽  
K Transport ◽  
Dependent Pathway ◽  
External K

The majority of the ouabain-insensitive K influx in human erythrocytes is dependent on the presence of Cl. Recent studies have shown that a portion of the Cl-dependent K influx persists in the absence of external Na (Nao). It has been suggested that this Nao-independent component represents (K + Cl) cotransport, whereas the remainder of the Cl-dependent K influx seen on addition of external Na represents (Na + K + 2Cl) cotransport. In the present studies, the kinetics of Cl-dependent K influx were examined in the presence and absence of external Na, by varying external K and external Cl. Our studies suggest that the Nao-independent Cl-dependent pathway has a relatively low affinity for external K (Km 17-30 mM) in contrast to the high affinity of the Nao-augmented component (Km 3-4 mM). N-ethylmaleimide (NEM) stimulates the maximal velocity of the Nao-independent Cl-dependent K influx achievable without alteration of intracellular solutes but does not alter its Km for external K. In contrast, NEM has no stimulatory effect on the Nao-augmented component. The Cl dependence of the Nao-independent K influx is best described by a relatively flat curve with a mild upward concavity. The kinetic properties of the Nao-independent component of Cl-dependent K transport are very similar to those of the putative (K + Cl) cotransport pathway seen in low-K sheep erythrocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Corrigendum to “Kinetics of extracellular ATP in mastoparan 7-activated human erythrocytes” [Biochim. Biophys. Acta — Gen. Subj. 1830 (10) (2013) 4692–4707]

2014 ◽  
Vol 1840 (6) ◽  
pp. 1837 ◽  
Author(s):  
María Florencia Leal Denis ◽  
J. Jeremías Incicco ◽  
María Victoria Espelt ◽  
Sandra V. Verstraeten ◽  
Omar P. Pignataro ◽  
...  
Keyword(s):  
Extracellular Atp ◽  
Human Erythrocytes ◽  
Kinetics Of

scholarly journals Direct Evidence for Catalase as the Predominant H2O2 -Removing Enzyme in Human Erythrocytes

Blood ◽  
1997 ◽  
Vol 90 (12) ◽  
pp. 4973-4978 ◽  
Author(s):  
Sebastian Mueller ◽  
Hans-Dieter Riedel ◽  
Wolfgang Stremmel
Keyword(s):  
Hydrogen Peroxide ◽  
Glutathione Peroxidase ◽  
Enzyme Inhibition ◽  
Direct Evidence ◽  
Human Erythrocytes ◽  
H2o2 Concentration ◽  
H2o2 Decomposition ◽  
Erythrocyte Catalase ◽  
Normal Human ◽  
Kinetics Of

Decomposition of hydrogen peroxide (H2O2 ) at physiological levels was studied in human erythrocytes by means of a recently developed sensitive H2O2 assay. The exponential decay of H2O2 in the presence of purified erythrocyte catalase was followed down to 10−9 mol/L H2O2 at pH 7.4. H2O2 decomposition by purified erythrocyte glutathione peroxidase (GPO) could be directly observed down to 10−7 mol/L H2O2 . No enzyme inhibition was observed at these low H2O2 concentrations. Catalase and GPO activities can be determined separately in a titrated mixture of purified enzymes, which simulates the conditions of H2O2 removal by the erythrocyte. Experiments with fresh human hemolysate allowed us to determine H2O2 decomposition by catalase and GPO using these enzymes in their original quantitative ratio. The different kinetics of these enzymes are shown: H2O2 decomposition by catalase depends linearly on H2O2 concentration, whereas that by GPO becomes saturated at concentrations above 10−6 mol/L H2O2 . Even at very low H2O2 concentrations GPO reaches only approximately 8% of the rate at which catalase simultaneously degrades H2O2 . These data indicate an almost exclusive role for catalase in the removal of H2O2 in normal human erythrocytes.

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