Control of oxygen affinity of hemoglobin in K562 cells induced by hemin
Y Wu, A Dean, W Egan and AN Schechter
The oxygen affinity of hemoglobin in K562 cells induced by hemin and the
relationship between levels of 2,3-diphosphoglycerate (2,3-DPG) and
hemoglobin have been investigated. Absorption spectra of induced cells
indicate that the hemoglobin is oxygenated; oxygen dissociation curves are
symmetric, with a P50 of 20 +/- 0.9 mm Hg, Hill coefficient of 2.5, and a
normal temperature dependence. The intracellular pH measured by phosphorus
31 nuclear magnetic resonance (NMR) was 7.3. The amount of 2,3-DPG was
determined by an enzymatic method and by 31P NMR. The level of 2,3-DPG in
uninduced K562 cells, containing 0.5 pg of hemoglobin per cell, was low (5
+/- 0.5 mumole/10(8) cells), but increased to 64 +/- 5 mumole/10(8) cells
upon induction of hemoglobin accumulation (to a final level of 20 pg
hemoglobin/cell). For several experiments, there was a closely coordinated
relationship between 2,3-DPG and hemoglobin levels, at about 1:1
stoichiometry of the two molecules. The time course of induction of
hemoglobin, and of 2,3-DPG levels, are very similar; both processes are
reversible. These data suggest that induction of hemoglobin synthesis in
K562 cells by hemin results in hemoglobin-containing cells with normal
oxygenation properties and that 2,3-DPG and hemoglobin levels are
coordinately controlled in these cells. Elucidation of the mechanism of
this effect should be of importance in understanding the erythroid-like
differentiation of these cells.
Volume 63,
Issue 6,
pp. 1447-1452,
06/01/1984
Copyright © 1984 by The American Society of Hematology
