[The role of oligomeric structure in the functioning of D-glyceraldehyde-3-phosphate dehydrogenase].
The review summarizes the results of a study on the functional role of subunit interactions in a tetrameric glyceraldehyde-3-phosphate dehydrogenase molecule. A conformational asymmetry preexistent in the apoenzyme was shown to be detectable with the use of fluorescent cationic probes. Experimental evidence is presented which points to an interaction of the enzyme active centers in the course of productive E-acyl-NADH complex formation in the forward reaction. The matrix immobilized oligomeric and subunit forms of the enzyme were used to demonstrate that the quaternary structure is not a prerequisite for the catalytic activity. Due to subunit interactions within the oligomeric enzyme molecule the functioning of a monomer is under the control exerted by the neighbouring subunits. An association of monomers into a dimer is sufficient to create a cooperative system; the mutual influence of subunits becomes more complex in a trimeric and a tetrameric enzyme species. An isolated dimer exhibits the effect of half-of-the-sites reactivity and catalytic cooperativity of the active centers. Both the tetrameric and dimeric enzyme forms probably catalyze the reaction of 1,3-diphosphoglycerate reductive dephosphorylation via a mechanism of the flip-flop type. The catalytic cooperativity of the enzyme active centers can be controlled by some factors of the intracellular environment (e.g., by protein-protein interactions with a functionally related enzyme). Thus, the role of subunit cooperativity in the glyceraldehyde-3-phosphate dehydrogenase molecule is suggested to constitute one of the mechanisms of regulation of the enzyme functioning.
D000818:Animals; D001665:Binding Sites; D004800:Enzymes, Immobilized; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism*; D007700:Kinetics; D009132:Muscles / Q000201:enzymology; D011487:Protein Conformation
D004800:Enzymes, Immobilized; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases
Rol' oligomernoĭ struktury v funktsionirovanii D-glitseral'degid-3-fosfatdegidrogenazy.