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. Author manuscript; available in PMC: 2013 Apr 1.
Published in final edited form as: J Steroid Biochem Mol Biol. 2011 Dec 28;129(3-5):139–144. doi: 10.1016/j.jsbmb.2011.12.002

Table 2.

Kinetic parameters of NOR and TIB as substrate of AKR1C enzymes.

AKR1C1 AKR1C2 AKR1C4
NOR kcat (min−1) 1.0 ± 0.1 8.2 ± 2.1 2.7 ± 0.2
Km (μM) 2.3 ± 0.2 1.5 ± 0.3 0.43 ± 0.04
kcat /Km (min−1μM−1) 0.45 5.6 6.4
Ki (μM) 2.3 ± 0.5
TIB kcat (min−1) 0.88 ± 0.06 12.7 ± 3.7 1.83 ± 0.06
Km (μM) 0.76 ± 0.13 0.87 ± 0.34 1.02 ± 0.07
kcat /Km (min−1μM−1) 1.2 14.6 1.8
Ki (μM) 0.7 ± 0.29

Values for AKR1C3-catalyzed reactions could not be determined due to low turnover. Values for TIB were from reference [15].