Table 1.

Kinetic parameters for wild-type and mutant forms of ATCase^a

Enzyme	Form	Vmax	[Asp]0.5	nH
		mmol h−1 mg−1	mM
Wild-type	Holoenzyme	19.3 ± 0.5	13.5 ± 0.9	2.6 ± 0.2
C47A/A241COXc	Holoenzyme	25.6 ± 0.9	2.3 ± 0.2	1b
C47A/A241CREDd	Holoenzyme	25.4 ± 2.3	10.8 ± 0.8	1.3 ± 0.1
C47A/A241C	C6e	55.6 ± 1.8	17.9 ± 0.8	1.7 ± 0.2
Wild-type	C3	22.9 ± 2.1	10.4 ± 0.8	1b
C47A/A241C	C3f	21.5 ± 1.9	8.7 ± 1.9	1b

^aData were determined from the Asp saturation curves (Figure 2), and are the average of 3 independent determinations. Colorimetric assays were performed at 25° C, in 50 mM Tris acetate buffer, pH 8.3, and at saturating levels of CP (4.8 mM)

^bNo cooperativity observed, data were fit to the Michaelis-Menten equation with an additional term for substrate inhibition.

^cDisulfide-linked C47A/A241C holoenzyme

^dReduced C47A/A241C holoenzyme

^eA part of catalytic subunits linked by disulfides

^fc₃ after reduction of the disulfide linked c₆.