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Mechanism of inhibition of glyceraldehyde‐3‐phosphate dehydrogenase activity by glucose
Author(s) -
Easterday Ashton,
Keil Natalie,
Subramaniam Ram
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a1015-b
Subject(s) - mechanism (biology) , glyceraldehyde 3 phosphate dehydrogenase , chemistry , dehydrogenase , glyceraldehyde , biochemistry , enzyme , philosophy , epistemology
Diabetes is a metabolic disorder that affects more than 200 million people worldwide. Vascular complications of diabetes are thought to be a result of increasing circulating sugars such as glucose and methylglyoxal (MGO). During one of the steps in glycolysis, the principle metabolic pathway for glucose, glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) converts glyceraldehyde‐3‐phosphate into 1, 3‐bisphosphoglycerate. We hypothesized that GAPDH activity is decreased as result of hyperglycemia and the mechanism of inactivation is due to an interaction of GAPDH with glucose and/or MGO. We measured the activity of GAPDH using spectrophotometric methods to observe the oxidative phosphorylation of glyceraldehyde‐3‐phosphate. Our results show that in both cell culture models of hyperglycemia (using RAW264.7 cells) and animal models of diabetes (streptozotocin‐induced diabetic mice), GAPDH activity is decreased. Further studies using commercially obtained rabbit muscle GAPDH showed that GAPDH activity is decreased due to glucose but not due to MGO and that neither sugars affect the conformation of the enzyme (as observed by fluorescence and circular dichroism spectroscopy). Based on our results we propose a novel mechanism for the glucose‐mediated inhibition of GAPDH activity due to interactions between glucose and the catalytic domain of GAPDH.