Glyoxylic acid prevents NAD+ and NADH depletion in K562 cells cultured at limiting dilution.
K562 erythroleukemic cells cultured at low population density in the absence of serum die within 12-24 hours, unless 0.1 mM glyoxylic acid is added to the culture medium. Earlier events, preceding cell death and occurring within 2 hours culture, are: a) a marked drop of both the NAD+/NADH ratio and the NAD+ concentration, which is prevented by 10mM benzamide, b) an increased biosynthesis of NAD+, leading to extensive depletion of cellular ATP. In the presence of 0.1 mM glyoxylic acid the NAD+/NADH ratio as well as their absolute concentrations remain unchanged, while NAD+ biosynthesis is absent. A NAD+/NADH glycohydrolase activity is present in the cell extract, inhibited by 10 mM benzamide and with a higher affinity for NADH than for NAD+. Preservation of a high NAD+/NADH ratio by glyoxylic acid apparently prevents enzyme activity and the related loss of pyridine nucleotides.
Zocchi
E
E
Department of Biochemistry, University of Genoa, Italy.
Polvani
C
C
Guida
L
L
D000241:Adenosine / Q000378:metabolism; D001549:Benzamides / Q000494:pharmacology; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D006038:Glyoxylates / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D004915:Leukemia, Erythroblastic, Acute; D009243:NAD / Q000378:metabolism*; D010084:Oxidation-Reduction
D001549:Benzamides; D006038:Glyoxylates; D009243:NAD; C037689:benzamide; C031150:glyoxylic acid; D000241:Adenosine