Table 1. Steady-State Kinetic Parameters for ChsE1-ChsE2, ChsE3, and ChsE4-ChsE5 with the Acyl-CoA Thioesters of the Cholesterol Side Chain Degradation Intermediates^a.

substrate	KM (μM)	kcat (s–1)	kcat/KM (M–1 s–1)
	ChsE1-ChsE2
3-OPC-CoA	5.3 ± 0.9b	1.30 ± 0.02b	(2.5 ± 0.5) × 105b
3-OCO-CoA	6.5 ± 0.9	0.16 ± 0.005	(2.4 ± 0.3) × 104
3-OCS-CoA	nac	nac	nac
	ChsE3
3-OPC-CoA	nac	nac	nac
3-OCO-CoA	28 ± 8	5.0 ± 0.5	(1.8 ± 0.9) × 105
3-OCS-CoA	nac	nac	nac
	ChsE4-ChsE5
3-OPC-CoA	3.3 ± 0.7	1.5 ± 0.05	(4.5 ± 0.9) × 105
3-OCO-CoA	2.6 ± 0.4	0.48 ± 0.01	(1.9 ± 0.3) × 105
3-OCS-CoA	3.4 ± 1.0d	2.7 ± 0.4d	(8.1 ± 2.5) × 105
	Kiu = 20 ± 2.7
octanoyl-CoA	4.1 ± 0.9	0.042 ± 0.002	(1.0 ± 0.2) × 104

^aError bars are the standard deviations of global fits to three independent experiments.

^bData from ref (17)

^cNo activity.

^dInhibition was observed with 3-OCS-CoA. The data were fit by assuming uncompetitive substrate inhibition.