. 2018 Aug 20;40(2):447–475. doi: 10.1210/er.2018-00089

Table 3.

Steady-State Kinetic Parameters for Human AKRs

Substrate	Product	Cofactor	Reduction	K _m (μM)	k _cat (min⁻¹)	k _cat/K_m (min⁻¹ mM⁻¹)
AKR1C1
Progesterone^R	20α-HydroxyP	NADPH	20-Ketosteroid	5.7	0.93	210^a
Androsterone	5α-Androstane-3α,17β-diol	NADPH	17-Ketosteroid	21	0.18	9^b
5α-DHT^R	5α-Androstane-3α,17β-diol	NADPH	3-Ketosteroid	81	0.66	8^b
AKR1C2
5α-DHT^R	5α-Androstane-3α,17β-diol	NADPH	3-Ketosteroid	4.6	3.8	820^a
5α-DHT^S	5α-Androstane-3α,17β-diol	NADPH	3-Ketosteroid	2.9	1.8	620^c
5α-DHP	3α-Hydroxy-5α-pregnane-20-one	NADPH	3-Ketosteroid	1.8	0.18	100^d
5β-DHP	3α-Hydroxy-5β-pregnane-20-one	NADPH	3-Ketosteroid	0.6	0.5	1200^e
4-Androstene-3,17-dione^R	Testosterone	NADPH	17-Ketosteroid	ND	ND	ND
AKR1C3
5α-DHT^R	5α-Androstane-3α,17β-diol	NADPH	3-Ketosteroid	19.8	0.26	6^a
5α-Androstane-3,17-dione^S	Androsterone;	NADPH	3-Ketosteroid	5.0	7.63	56^a
5α-Androstane-3,17-dione^S	5α-DHT	NADPH	17-Ketosteroid	5.0	7.63	56^a
4-Androstene-3,17-dione^R	Testosterone	NADPH	17-Ketosteroid	13.4	0.87	65^f
Androsterone^S	5α-Androstane-3α,17β-diol	NADPH	17-Ketosteroid	8.9	10.2	42^a
Estrone^R	17β-Estradiol	NADPH	17-Ketosteroid	9.0	0.068	7.5^g
Progesterone	20α-HydroxyP	NADPH	20-Ketosteroid	2.8	1.0	370^f
AKR1C4
5α-DHT^R	5α-Androstane-3α,17β-diol	NADPH	3-Ketosteroid	8.3	1.92	231^a
5β-DHT	5β-Androstane-3α,17β-diol	NADPH	3-Ketosteroid	0.2	4.7	23,500^e
5β-DHP	3α-Hydroxy-5β-pregnane-20-one;	NADPH	3-Ketosteroid	0.3	4.9	16,300^e
5β-DHP	5β-Pregnane-3α,20α-diol	NADPH	20-Ketosteroid	0.3	4.9	16,300^e
20α-Hydroxy-5β-pregnane-3-one	5β-Pregnane-3α,20α-diol	NADPH	3-Ketosteroid	0.3	4.3	14,300^e
3α-Hydroxy-5β-pregnane-20-one	5β-Pregnane-3α,20α-diol	NADPH	20-Ketosteroid	0.4	1.5	3800^e
AKR1D1
Testosterone	5β-Dihydrotestosterone	NADPH	5β-Reduction	2.7	8.4	3120^h
Cortisol	5β-Dihydrocortisol	NADPH	5β-Reduction	13.1	2.7	210^h
Cortisone	5β-Dihydrocortisone	NADPH	5β-Reduction	15.1	11.7	780^h
4-Cholesten-7α-ol-3-one	7α-Hydroxy-5β-dihydrocholestan-3-one	NADPH	5β-Reduction	0.8	2.0	2530^h
Cholestenone	5β−dihydrochlestenone	NADPH	5β-Reduction	0.3	0.60	1980^d

Abbreviation: ND, not determined.

^{^a}

Byrns et al., 2008, Biochem Pharmacol (56).

^{^b}

Penning et al., 2000, Biochem J (24).

^{^c}

Jin and Penning, 2006, Biochemistry (54).

^{^d}

Trauger et al., 2002, Biochemistry (55).

^{^e}

Jin et al., 2011, Biochem J (34).

^{^f}

Sharma et al., 2006, Mol Cell Endocrinol (36).

^{^g}

Byrns et al., 2010, J Steroid Biochem Mol Biol (26).

^{^h}

Chen et al., 2011, Steroids (37).