Human cytochrome b5 requires residues E48 and E49 to stimulate the 17,20-lyase activity of cytochrome P450c17.

@article{NaffinOlivos2006HumanCB,
  title={Human cytochrome b5 requires residues E48 and E49 to stimulate the 17,20-lyase activity of cytochrome P450c17.},
  author={Jacqueline L Naffin-Olivos and Richard J Auchus},
  journal={Biochemistry},
  year={2006},
  volume={45 3},
  pages={755-62}
}
Cytochrome P450c17 (CYP17) catalyzes both the 17alpha-hydroxylase and 17,20-lyase reactions in human steroid biosynthesis. Cytochrome b5 (b5) stimulates the rate of the 17,20-lyase reaction 10-fold with little influence on 17alpha-hydroxylase activity. Studies with apo-b5 suggest that stimulation of 17,20-lyase activity results from an allosteric action on the hCYP17 x POR complex, rather than electron transfer by b5. We hypothesized that specific residues on b5 interact with the hCYP17 x POR… CONTINUE READING