. Author manuscript; available in PMC: 2011 Apr 27.

Published in final edited form as: Biochemistry. 2010 Apr 27;49(16):3487–3498. doi: 10.1021/bi100294m

Table 1.

Kinetic Parameters for R- and S-HPCDH with physiological substrates in the forward and reverse directions^a

	rR-HPCDH1			rS-HPCDH1			rS-HPCDH3
Substrate	K_m (μM)	k_cat (s^-1)	k_cat/K_m (M^-1 s^-1)	K_m (μM)	k_cat (s^-1)	k_cat/K_m (M^-1 s^-1)	K_m (μM)	k_cat (s^-1)	k_cat/K_m (M^-1 s^-1)
R-HPC	96 ± 7	48 ± 1	5.0 × 10⁵	5200 ± 300	2.4 ± 0.06	4.6 × 10²	9100 ± 1100	5.5 ± 0.2	1.2 × 10³
S-HPC	220 ± 70	0.12 ± 0.01	5.3 × 10²	220 ± 20	28 ± 0.8	1.3 × 10⁵	31 ± 0.9	25 ± 0.2	7.9 × 10⁵
2-KPC	68 ± 10	29 ± 2	4.2 × 10⁵	240 ± 10	20 ± 0.2	8.3 × 10⁴	270 ± 13	11 ± 0.2	3.9 × 10⁴

Assay for R-HPC and S-HPC oxidation by rR-HPCDH1 contained 1.0 μg and 46 μg of enzyme, respectively. Assay for R-HPC and S-HPC oxidation by rS-HPCDH1 and rS-HPCDH3 contained 5.0 μg and 1.0 μg of enzyme, respectively. Assay for 2-KPC reduction contained 1 μg of enzyme. Apparent k_cat and K_m values are reported as means ± standard deviations. All assays were performed in triplicates at 30 °C with fixed concentrations of NAD⁺ (10 mM) or NADH (0.17 mM). Apparent kinetic constants were determined by fitting experimental data to the standard form of the Michaelis-Menten equation.