scholarly journals Fructose-6-phosphate,2-kinase activity in human erythrocytes

Blood ◽  
1987 ◽  
Vol 70 (4) ◽  
pp. 1211-1213 ◽  
Author(s):  
S Fujii ◽  
M Matsuda ◽  
S Okuya ◽  
Y Yoshizaki ◽  
Y Miura-Kora ◽  
...  
Keyword(s):  
Pyruvate Kinase ◽  
Adenosine Triphosphate ◽  
Kinase Activity ◽  
Human Erythrocytes ◽  
Red Cells ◽  
Half Maximum ◽  
Maximum Activation ◽  
Rate Limiting ◽  
Human Red Cells

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.

scholarly journals Fructose-6-phosphate,2-kinase activity in human erythrocytes

Blood ◽  
1987 ◽  
Vol 70 (4) ◽  
pp. 1211-1213
Author(s):  
S Fujii ◽  
M Matsuda ◽  
S Okuya ◽  
Y Yoshizaki ◽  
Y Miura-Kora ◽  
...  
Keyword(s):  
Pyruvate Kinase ◽  
Adenosine Triphosphate ◽  
Kinase Activity ◽  
Human Erythrocytes ◽  
Red Cells ◽  
Half Maximum ◽  
Maximum Activation ◽  
Rate Limiting ◽  
Human Red Cells

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.

scholarly journals Glycolate kinase activity in human red cells

Blood ◽  
1985 ◽  
Vol 65 (2) ◽  
pp. 480-483 ◽  
Author(s):  
S Fujii ◽  
E Beutler
Keyword(s):  
Pyruvate Kinase ◽  
Adenosine Triphosphate ◽  
Kinase Activity ◽  
Maximum Velocity ◽  
Red Cells ◽  
Half Maximum ◽  
Ph Optimum ◽  
Pyruvate Kinase Deficiency ◽  
Low Activity ◽  
Human Red Cells

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.

scholarly journals Glycolate kinase activity in human red cells

Blood ◽  
1985 ◽  
Vol 65 (2) ◽  
pp. 480-483
Author(s):  
S Fujii ◽  
E Beutler
Keyword(s):  
Pyruvate Kinase ◽  
Adenosine Triphosphate ◽  
Kinase Activity ◽  
Maximum Velocity ◽  
Red Cells ◽  
Half Maximum ◽  
Ph Optimum ◽  
Pyruvate Kinase Deficiency ◽  
Low Activity ◽  
Human Red Cells

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.

scholarly journals Haemolytic Effects of Hypo-osmotic Salt Solutions on Human Erythrocytes

2012 ◽  
Vol 9 (2) ◽  
pp. 35-39 ◽  
Author(s):  
O Nepal ◽  
J P Rao
Keyword(s):  
Sodium Chloride ◽  
Morphological Changes ◽  
Nickel Chloride ◽  
Human Erythrocytes ◽  
Red Cells ◽  
Salt Solutions ◽  
Potassium Salts ◽  
Blood Samples ◽  
Chloride Salts ◽  
Human Red Cells

Background While it is well known that hypotonic solutions of sodium chloride induce hemolysis, the effects of other salt solutions on human erythrocytes have not been well documented. Objective The study is to compare the effects of other salt solutions on human red cells. Methods Iso-osmotic and hypo-osmotic solutions of various salts were prepared after taking into account their molecular weight and osmotic pressure. Five healthy volunteers between the age of 22-30 years were randomly selected and ten blood samples were collected from them. The study was conducted from January 2009 to February 2009. Blood was collected from subjects by venepuncture into heparinised tubes. 20 ?l of blood was pipetted into 1 ml of each solution and incubated for one hour at 37ºC in a water bath. The solutions were centrifuged and the colour of the supernatant was read in a spectrophotometer. Supernatant from blood added to distilled water was considered 100% hemolysed. Results Iso-osmotic salt solutions were free of hemolysis. Among chloride salts, sodium chloride showed the least hemolysis and potassium chloride and nickel chloride resulted into greater hemolysis. Among potassium salts, potassium bromate caused highest amount of hemolysis whereas potassium sulphate showed the least. Conclusion The significant differences in hemolytic pattern in hypo-osmotic salts solutions suggest that the hypo-osmotic stress causes morphological changes in red cells that alter their permeability to various ions leading to hemolysis. This probably occurs through opening of volume sensitive channels. DOI: http://dx.doi.org/10.3126/kumj.v9i2.6285Kathmandu Univ Med J 2011;9(2):35-9

Asymmetry of Na-K-Cl cotransport in human erythrocytes

1988 ◽  
Vol 254 (2) ◽  
pp. C243-C250 ◽  
Author(s):  
G. R. Kracke ◽  
M. A. Anatra ◽  
P. B. Dunham
Keyword(s):  
Human Erythrocytes ◽  
Red Cells ◽  
Mutual Dependence ◽  
L Cells ◽  
Na Efflux ◽  
Cotransport System ◽  
Human Red Cells

The Na-K-Cl cotransport system in human erythrocytes was studied by measuring net influxes and effluxes of Na and K. The influx of K was shown to be stimulated by Na and the influx of Na was stimulated by K, satisfying the fundamental criterion of cotransport. In addition, these mutually stimulating cation influxes had a stoichiometry of 1:1 and were entirely inhibited by furosemide; these results are also consistent with cotransport. Furthermore, the mutually stimulating influxes were entirely dependent on Cl, since they were abolished when nitrate was substituted for Cl. In contrast, cotransport, defined by mutual dependence of fluxes, was not detected in the outward direction over a range of cellular Na and K concentrations from 0 to 50 mmol/l cells. The cotransport pathway did, however, appear to mediate a Na-stimulated K efflux (but no K-stimulated Na efflux), and furosemide-inhibitable effluxes of both Na and K. Nitrate (but not sulfate) appeared to substitute for chloride in promoting Na-stimulated K efflux. Thus the Na-K-Cl cotransport system in human red cells is intrinsically asymmetric, and mediates coupled cation fluxes readily only in the inward direction.

Adenosine Triphosphate and Maintenance of Shape of the Human Red Cells

Nature ◽  
1960 ◽  
Vol 187 (4741) ◽  
pp. 945-946 ◽  
Author(s):  
MAKOTO NAKAO ◽  
TOSHIKO NAKAO ◽  
SABURO YAMAZOE
Keyword(s):  
Adenosine Triphosphate ◽  
Red Cells ◽  
Human Red Cells
Sign in / Sign up

Export Citation Format

Share Document