Inactivation precedes changes in allosteric properties and conformation of D-glyceraldehyde-3-phosphate dehydrogenase and fructose-1,6-bisphosphatase during denaturation by guanidinium chloride.
It has been shown that inactivation of several enzymes precedes overall conformational changes of the enzyme molecules as a whole during denaturation [Tsou (1993) Science, 262, 380-381]. However, the relation between inactivation, loss of allosteric properties of oligomeric enzymes and unfolding of the enzyme molecule during denaturation remain little explored. These have now been compared for D-glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and fructose-1,6-bisphosphatase (FruP2ase) during denaturation by guanidinium chloride (GdmCl). GAPDH is completely inactivated at 0.3 M GdmCl but at this GdmCl concentration it still binds NAD+ with negative co-operativity. At 0.4 M GdmCl, inactivation of FruP2ase reaches completion whereas its allosteric properties, including the heterotropic effect of AMP inhibition and K+ activation with positive co-operativity, are only partially affected. Much higher GdmCl concentrations are required to bring about unfolding of the overall structures of both enzymes.
Jiang
R F
RF
National Laboratory of Biomacromolecules, Institute of Biophysics, Academia Sinica, Beijing, China.
Tsou
C L
CL
D000249:Adenosine Monophosphate / Q000378:metabolism; D000494:Allosteric Regulation; D000495:Allosteric Site; D000818:Animals; D004789:Enzyme Activation; D006597:Fructose-Bisphosphatase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism; D019791:Guanidine; D006146:Guanidines / Q000494:pharmacology*; D007700:Kinetics; D009132:Muscles / Q000201:enzymology; D011188:Potassium / Q000494:pharmacology; D011485:Protein Binding; D011487:Protein Conformation; D011489:Protein Denaturation; D011817:Rabbits; D012911:Snakes; D013056:Spectrophotometry, Ultraviolet
D006146:Guanidines; D000249:Adenosine Monophosphate; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D006597:Fructose-Bisphosphatase; D019791:Guanidine; D011188:Potassium