Table 1.

Effect of active-site mutations on the three redox-dependent activities of 2-KPCC^a

Enzyme	Specific activityb (nmol/min/mg) for:
	2-KPC protonation	2-KPC carboxylation	Formation of 2-KPC from acetoacetate
wt r-2-KPCC	53.8 ± 6.4	221 ± 16	47 ± 4
C87A r-2-KPCC	ND	ND	ND
C82A r-2-KPCC	ND	ND	ND
H84A r-2-KPCC	22.7 ± 0.1	37.0 ± 4.2	12.0 ± 0.3
H137A r-2-KPCC	ND	18 ± 1	1.0 ± 0.1

^aAll assays were repeated in duplicate. 2-KPC protonation and carboxylation assays were performed using DTT as the reductant, while formation of 2-KPC from acetoacetate was performed using NADP⁺ as the oxidant.

^bND, no detectable activity.