Insight into the Mechanistic Basis of the Hysteretic-Like Kinetic Behavior of Thioredoxin-Glutathione Reductase (TGR)

Table 1

Summary of kinetic parameters of T. crassiceps TGR.

Parameter	Experimental value	Theoretical value
NADPH	3.5 ± 0.4 µM (n = 6)	1.8 µM
GSSG	14.4 ± 2.3 µM (n = 6)	6.6 µM
GSSG	100 ± 22 µM (n = 6)	47 µM
	12 ± 2.4 s^−1 (n = 6)	7.4 s^−1
NADPH	3.43 x 10^6	4.12 x 10^6
GSSG	0.83 x 10^6	1.12 x 10^6
GSSG	331 ± 79 µM (n = 6)	512 µM
	55.3 ± 3.5 (n = 4)	nd
	37.6 ± 5.1 (n = 4)	nd

a: determined by fitting the corresponding rate equation to initial velocity data. Data represent mean ± standard deviation of the n replicates (in parenthesis); b: determined from the values of the theoretical rate constants and the definition of the corresponding kinetic parameter as derived from the mechanism-based model; c: an uncompetitive inhibition regarding GSSG; d: competitive inhibition regarding NADPH; nd not determined.