Stimulation of glyceraldehyde-3-phosphate dehydrogenase by oxyhemoglobin.
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a key glycolytic enzyme regulated by many diverse mechanisms. In this study we present evidence that GAPDH activity is stimulated in the presence of oxyhemoglobin (2.3-fold, P < 0.005). No stimulation was seen by myoglobin, and only slight stimulation (1.2-fold, not significant) by methemoglobin was observed. Such stimulation may have physiological significance as 1,3-bis-phosphoglycerate, the product of GAPDH, isomerises to 2,3-bis-phosphoglycerate, an allosteric effector that decreases the oxygen affinity of hemoglobin, thus providing a feedback loop. The results suggest that when assaying GAPDH activity in biological samples, hemoglobin content should be taken into account.
Brookes
P S
PS
Department of Neurochemistry, Institute of Neurology, London, UK. pbrookes@ion.ucl.ac.uk
Land
J M
JM
Clark
J B
JB
Heales
S J
SJ
D000818:Animals; D004789:Enzyme Activation; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism*; D008099:Liver / Q000201:enzymology; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D010108:Oxyhemoglobins / Q000494:pharmacology*
D010108:Oxyhemoglobins; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases