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Nitric oxide generation in brain cytosolic fractions markedly enhances ADP-ribosylation of a single 37-kDa protein. By utilizing a biotinylated NAD and avidin affinity chromatography, we purified this protein. Partial amino acid sequencing establishes its identity as glyceraldehyde-3-phosphate dehydrogenase (GAPDH). This is further confirmed by detection of GAPDH enzymatic activity in the purified 37-kDa protein. GAPDH is ADP-ribosylated in the absence of brain extract. This auto-ADP-ribosylation is enhanced by nitric oxide generation. ADP-ribosylation appears to involve the cysteine where NAD interacts with GAPDH so that ADP-ribosylation likely inhibits enzymatic activity. Such inhibition may play a role in nitric oxide-mediated neurotoxicity.
Zhang et al. (Thu,) studied this question.