Fig. 5.

Schematic representation of electron transfer in various catalytic system hydroxylating steroids. CYP = scheme according to (Hannemann et al. 2007), FdR = ferrodoxin reductase, Fdx = ferrodoxin, P450 = cytochrome P450 monooxygenase; KSH according to (Petrusma et al. 2014), KshB = ferrodoxin reductase component, KshA = terminal oxygenase component; S25DH according to (Heider et al. 2016), α = catalytic subunit, β = electron transfer subunit, γ = subunit with heme b transferring electrons to external acceptor. In dark gray = catalytic subunits. St = steroid. Red arrow marks the electron transfer pathways