TABLE 2.

Steroid substrate range of the KSH enzyme of R. rhodochrous DSM 43269a

Steroid substrateExptl Vmax (nmol min−1 mg−1)Relative activity (%)
AD276 ± 20100
ADD246 ± 2089
4-Androstene-17β-ol-3-one (testosterone)279 ± 29101
4-Pregnene-3,20-dione (progesterone)272 ± 3899
19-Nor-4-androstene-3,17-dione (nordion)216 ± 2578
1-(5α)-Androstene-3,17-dione188 ± 2068
5α-Androstane-3,17-dioneb177 ± 1964
5β-Androstane-3,17-dioneb160 ± 2258
5-Cholestene-3β-ol (cholesterol)cNDND
5α-Androstane-17β-ol-3-one (stanolon)NDND
5α-Androstane-17-oneNDND
3α-Hydroxy-5α-pregnane-20-onecNDND
11β-HydrocortisoneNDND
3β-Hydroxy-5α-androstane-17-oneNDND
4-Cholestene-3-onecNDND
4-Pregnene-3-one-20β-carboxylic acidcNDND
9OHAD (negative control)NDND
  • a Experimental enzyme activities (Exptl Vmax) at a 100 μM steroid substrate concentration were calculated in nmol−1·min−1·mg−1 KSH enzyme. The relative activities are expressed as percentages of the activity with AD, which was set at 100%. Errors were calculated as standard errors of the means (from three experiments). Steroid structures are shown in Fig. S1 in the supplemental material. ND, no detectable activity.

  • b Steroid substrate concentration, 200 μM.

  • c Steroid substrate concentration, 25 μM, due to the low solubility of the substrate.