Fructose 3-phosphate and 5-phosphoribosyl-1-pyrophosphate formation in perfused human erythrocytes : 31P NMR studies

• 31P NMR was used to study the formation of fructose 3-phos-phate (F3P) and 5-phosphoribosyl-1-pyrophosphate (PRPP) in perfused human erythrocytes, in the presence of 10 different combinations and concentrations of glucose, inosine, pyru-vate, fructose, and inorganic phosphate (Pi). (1) The cells were immobilized in alginate-coated agarose threads and perfused with a medium containing fructose, and the level of F3P increased continuously over more than 10 h. The net rate of F3P formation was independent of the concentration of 2,3-bis-phosphoglycerate (2,3-DPG) present in the cells. (2) PRPP was formed in high concentrations, relative to normal, in immobilized cells when they were perfused with a medium containing Pi at a low pH (6.6). (3) The 2,3-DPG level decreased simultaneously when the sample was perfused with a medium containing fructose, but without inosine or pyruvate. The measured intracellular pH and free Mg2+ concentration were constant in these experiments. (4) The experiments confirmed the presence of fructose-3-phosphokinase (E.C. 2.7.1.-) and ribose-phosphate pyrophosphokinase (E.C. 2.7.6.1) activity in the human erythrocytes and that the biosynthetic pathways are active in immobilized cells at 37°C. (5) The rates of accumulation of 2,3-DPG and phosphomonoesters (PME) appeared to be strongly correlated.

Ämnesord

NATURVETENSKAP  -- Kemi -- Fysikalisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Physical Chemistry (hsv//eng)

Nyckelord

cell immobilization;perfused human erythrocytes;fructose 3-phosphate;5-phosphoribosyl-1-pyrophos-phate

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