Received April 16, 2001; Revision received June 10, 2001
The properties of the active center of phosphorylating D-glyceraldehyde-3-phosphate dehydrogenase (GAPDH) are considered with emphasis on the structure of anion-binding sites and their role in catalysis. The results of studies on the molecular mechanism of the effect of NAD+ on the enzyme conformation are discussed. Experimental evidence is presented supporting the idea that negative cooperativity of NAD+ binding and half-of-the-sites reactivity exhibited by GAPDH are generated by different mechanisms. Data obtained with rabbit muscle and Escherichia coli GAPDH point to preexisting asymmetry in these tetramers. Structural determinants that can control the transition of the tetramer from the symmetric to the asymmetric state were found.
KEY WORDS: D-glyceraldehyde-3-phosphate dehydrogenase, catalytic mechanism, active center, domains, half-of-the-sites reactivity, preexisting asymmetry