Similarly, substrates with short C17 substituents had average interaction energy with membrane-associated domain in the range of -11.1 to -4.5 kcal/mol, while for cholest-4-en-3one and diosgenone -15.7 and -13.5 kcal/mol, respectively (Figure ). Accordingly, the interaction with the whole protein was in the range of -53 to -40 kcal/mol, except for cholest-4-en-3-one and diosgenone, for which it was approximately -60 kcal/mol. Closer analysis indicates that the beginning of the membrane-associated domain is primarily responsible for the stabilization of the substrates. The T156 universally stabilizes both smaller and bigger substrates, while the hydrophobic residues between M164 and A169 are involved in the stabilization of substrates with extended C17 substituents. These results suggest that the group is significantly longer in the case of DHT compared to the native substrate CHON (median of 3.48 Å vs 2.94 Å, respectively).