Addition of pyruvate to human red cells incubated in vitro at alkaline pH values inhibits the accumulation of phosphate esters otherwise observed as well as the decrease of ATP and the corresponding increase of ADP and AMP. The increase of glycolysis at alkaline pH values is only partly due to a pH effect per se. About one-half of it is caused by a partial release of the inhibition of phosphofructokinase by a lowering of the ATP concentration and particularly by the increase of AMP. Only in the presence of pyruvate there occurs an increase of 2,3-bisphosphoglycerate, such as is observed in vivo, which is balanced by the consumption of pyruvate. At alkaline pH values in the absence of pyruvate there is a low movement from the fructose-1,6-bisphosphate + triosephosphates pool to the components of the pentose phosphate pathway, mostly by way of recombination from glyceraldehyde-phosphate.

Glyceraldehyde

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Citations (3)

The breakdown of adenine nucleotides in glucose-depleted human red cells.

PubMed (1979)

Iris Rapoport С. И. Рапопорт D Maretzki R Elsner

1) The rate of 2,3-bisphosphoglycerate breakdown is independent of pH value. 2) The adenine nucleotide pattern at alkaline pH values with its characteristic lowering of ATP and the accompanying accumulation of fructose-1,6-bisphosphate is caused by a relative excess of the activity of the hexokinase-phosphofructokinase system as compared wity pyruvate kinase. 3) The breakdown of adenine nucleotides proceeds via AMP mainly through phosphatase and not via AMP deaminase. 4) The constancy of the sum of nucleotides as long as glucose is present is postulated to be due to resynthesis via adenosine kinase which competes successfully with adenosine deaminase. 5) A procedure is given to calculate ATPase activity of glucose-depleted red cells. The results indicate that the ATPase activity is less at lower pH values and declines with time. An ATPase with a high Km for ATP is postulated. 6) During glucose depletion ATP production is mostly derived from the breakdown of 2,3-bisphosphoglycerate and the supply from the pentose phosphate pool both of which proceed at a constant rate. The contribution of pentose phosphate from the breakdown of adenine nucleotides amounts to 40% of the lactate formed at pH 6.8 and is about twice the lactate at pH 8.1.

Adenine nucleotide

Hexokinase

AMP deaminase

Adenine phosphoribosyltransferase

Adenosine triphosphate

Adenosine diphosphate

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Citations (5)

Response of the glycolysis of human erythrocytes to the transition from the oxygenated to the deoxygenated state at constant intracellular pH

Biochimica et Biophysica Acta (BBA) - General Subjects (1976)

Iris Rapoport Howard Berger S. Rapoport R Elsner Gerhard Gerber

Deoxygenation

Hexokinase

Phosphofructokinase 1

10.1016/0304-4165(76)90120-3

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Citations (28)

pH‐Dependent Changes of 2,3‐Bisphosphoglycerate in Human Red Cells during Transitional and Steady States in vitro

European Journal of Biochemistry (1977)

Iris Rapoport Hartmut Berger R Elsner S. Rapoport

A systematic study of the pH-dependent changes in the range 6.6--7.4 of 2,3-bisphosphoglycerate and the adenine nucleotides was performed in the presence and absence of glucose during transitional and steady states. 1. The results indicatethat 2,3-gisphosphoglycerate phosphatase breaks down 2,3-bisphosphoglycerate nearly independent of pH at a rate of 480 mumol 2,3-bisphosphoglycerate x1 cells-1xh-1.2,3-Bisphosphoglycerate mutase is practically completely inhibited below pH value increases in long-term experiments with lower 2,3-bisphosphoglycerate levels. The formation of pyruvate corresponds to the breakdown of 2,3-bisphosphoglycerate afterconsumption of an unknown reducing substance.

10.1111/j.1432-1033.1977.tb11333.x

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Citations (48)

NADPH production in the oxidative pentose phosphate pathway as source of reducing equivalents in glycolysis of human red cells in vitro.

PubMed (1979)

Iris Rapoport R Elsner Marco Müller R Dumdey S. Rapoport

Studies have been carried out on human erythrocytes in vitro to clarify the deficit of pyruvate formation under conditions when 2,3 DPG is degraded. The results lead to the conclusion that there exist a cross connection between the glycolytic and the oxidative pentose phosphate pathway which is mediated by the NADP/NADPH couple. NADPH serves as additional reducing equivalent in the reaction of the LDH. In the absence of glucose the pool of the metabolites of the pentose phosphate pathway is able to supply glucose-6-phosphate for the production of NADPH by recombination. The reaction of NADPH at the LDH is probably of significance under in vivo conditions.

Pentose

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Citations (9)

[ATP-dependent and ATP-independent changes in deformability of human erythrocytes].

PubMed (1980)

C Tannert Amrei Steinhoff Iris Rapoport R Elsner Rapoport Sm

By means of a simple filtration procedure it is shown that the deformability of red blood cells depends indirectly on their relative ATP-concentration. Losses in deformability were observed even with concentrations of ATP, which occur in the course of normal ageing of red blood cells in situ. If erythrocytes are incubated for longer times, their membrane is alterated to such a degree, that the changes cannot be reversed solely by restitution of ATP. The cells remain rigid.

Erythrocyte deformability

Adenosine triphosphate

Filtration (mathematics)

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Citations (1)

The effect of temperature and ouabain on the breakdown of ATP and 2,3-bisphosphoglycerate in glucose-depleted human red cells.

PubMed (1979)

Tu Ld D Maretzki С. И. Рапопорт Iris Rapoport C. Schewe

Ouabain exerts only a minor effect on ATP breakdown at 37 degrees C and practically none at 4 degrees C. The effect is less at higher pH values. At 4 degrees C the rates of breakdown at ATP, AMP and of 2,3 P2G are nearly two orders of magnitude less than at 37 degrees C.

Adenosine triphosphate

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[Changes in the enzymatic capacity of hexokinase, phosphofructokinase and pyruvate kinase in red blood cells in preservation with ACD and citrate-free stabilizers].

PubMed (1966)

G Jacobasch Raderecht Hj S Scheerer C Boese R Elsner

Hexokinase

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