Kinetic differentiation between enzyme inactivation involving complex-formation with the inactivator and that involving a conformation-change step.
It has been suggested that the complexing type of inactivation in which the inactivator binds reversibly with the enzyme before inactivation cannot be differentiated kinetically from that a slow enzyme conformation change is involved as a first step [Rakitzis (1986) J. Theor. Biol. 122, 247-249]. The kinetics of the substrate reaction during modification of enzyme activity previously described [Tsou (1988) Adv. Enzymol. Relat. Areas Mol. Biol. 61, 381-436] have now been applied to this problem and equations derived to show that the slow-conformational-change type can be differentiated from the complexing type by plotting the final concentration of product formed, [P]infinity, against the reciprocal of inactivator concentration. The reaction of hexokinase with 2-chloromercuri-4-nitrophenol has been shown to involve a conformational change of the enzyme before inactivation.
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National Laboratory of Biomacromolecules, Institute of Biophysics, Academia Sinica, Beijing, People's Republic of China.
Tsou
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D002730:Chloromercurinitrophenols / Q000378:metabolism; D002918:Chymotrypsin / Q000037:antagonists & inhibitors / Q000378:metabolism; D003174:Complement C1 Inactivator Proteins; D004791:Enzyme Inhibitors; D006593:Hexokinase / Q000037:antagonists & inhibitors; D007610:Kallikreins / Q000037:antagonists & inhibitors / Q000378:metabolism; D007700:Kinetics; D008433:Mathematics; D011487:Protein Conformation
D002730:Chloromercurinitrophenols; D003174:Complement C1 Inactivator Proteins; D004791:Enzyme Inhibitors; D006593:Hexokinase; D007610:Kallikreins; D002918:Chymotrypsin