Impaired nicotinamide adenine dinucleotide synthesis in pyruvate kinase-
deficient human erythrocytes: a mechanism for decreased total NAD content
and a possible secondary cause of hemolysis
CR Zerez and KR Tanaka
Erythrocytes from individuals with pyruvate kinase (PK) deficiency have
approximately half the total (oxidized and reduced) nicotinamide adenine
dinucleotide (NAD) of normal erythrocytes. In order to elucidate the
mechanism(s) for the decrease in total NAD, we examined NAD synthesis in
intact erythrocytes. It is demonstrated that NAD synthesis is impaired in
PK-deficient erythrocytes to a degree that is dependent on the PK activity
and adenosine 5'-triphosphate (ATP) concentration of these cells. After
incubation in the presence of fluoride, which simulates the characteristics
of PK deficiency by inhibiting enolase, normal erythrocytes had impaired
NAD synthesis and decreased ATP concentrations. Fluoride did not inhibit
NAD synthesis in a hemolysate system that is not dependent on glycolysis
for ATP generation. These data suggest that fluoride does not inhibit the
enzymes of NAD synthesis and that impairment of NAD synthesis by fluoride
is mediated by decreased ATP formation. Thus, it is concluded that impaired
NAD synthesis in PK-deficient erythrocytes is caused by decreased ATP
formation due to the PK deficiency. Since the rate of glycolysis is limited
by the availability of NAD+, it is suggested that impaired NAD synthesis
causes further ATP depletion and thereby may enhance hemolysis in
PK-deficient erythrocytes.
Volume 69,
Issue 4,
pp. 999-1005,
04/01/1987
Copyright © 1987 by The American Society of Hematology
