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. Author manuscript; available in PMC: 2019 Oct 1.
Published in final edited form as: Biochim Biophys Acta Mol Cell Biol Lipids. 2018 Jul 22;1863(10):1164–1178. doi: 10.1016/j.bbalip.2018.07.004

Table 2.

Comparison of binding and catalytic properties of AcCYP51 and AcSMTs for sterol.

Substrate1 AcCYP51 SMT5
Kd (μM)2 AfCPR kcat (min−1)3 24-SMT kcat(min−1) 28-SMT kcat(min−1)
10 4α, 14α-Dimethylergosta-8,24(28)-dienol 41 ±3 7.6 ±0.05 0 0
32 Lanosta-8,24(28)-dienol 51 ±10 3.2 ±0.04 nd nd
33 Lanosta-8,24(25)-dienol 46 ±3 1.7 ±0.01 1.50 ±0.01 0.23 ±0.01
34 Lanost-8-enol 60±12 2.0 ±0.002 nd nd
35 14α-Methylcholest-8,24(25)-dienol 12 ±2 1.6 ±0.08 1.50 ±0.05 0.39 ±0.02
24 4α-Methylcycloart-24(28)-enol No fit 0.04 ±0.01 nd nd
21 Cycloart-24(25)-enol 18 ±5 0 1.50 ±0.07 0.45 ± 0.03
27 Cycloart-24(28)-enol No fit 0 0 0.23 ±0.05
36 Lanosta-7,24(25)-dienol Nd4 0 nd nd
37 4α, 14α-Dimethyl cholesta-8,24(25)-dienol nd 0 1.50 ±0.04 0.74 ±0.02
14 4α-Methylergosta-7,24(28)-dienol nd 0 0 0.80 ± 0.04
1

See supplemental Figure 3 for a key to structures;

2

Kd value was determined by progressive titration of 4 M AcCYP51 with sterol in 40% (W/V) HPCP;

3

kcat was determined in the CYP51 reconstitution assays for 50 μM sterol using AfCPR redox partners;

4

nd, not determined;

5

Kinetic constants for SMT were determined previously for these sterols assayed in the range 5 μM to 150 μM against 150 μM SAM and 80 μg SMT as described in reference 33.