Thermodynamics of interactions between mammalian cytochromes P450 and b5

Role of Protein-Protein Interactions in Metabolism: Genetics, Structure, Function

“…The CYP-b 5 interactions that were enthalpy driven tended to belong to CYPs that were allosterically regulated by b 5 (i.e., whose activity could be modulated by b 5 ), whereas the CYP-b 5 interactions that were entropy driven tended to represent the CYP's whose activity was unaffected by b 5 . The authors attributed the differences in these effects to positive H values corresponding to displacement of the solvation shells of proteins upon clustering (Yablokov et al, 2017).…”

“…Early studies with CYP enzymes demonstrated the sensitivity of this technology in monitoring ligand binding directly to CYP enzymes, paving the way for more sophisticated protein-protein interaction studies (Pearson et al, 2006). More recently, this technology has been applied to examining CYP interactions with electron transfer partners (Ivanov et al, 1997(Ivanov et al, , 1999(Ivanov et al, , 2001Kuznetsov et al, 2004;Archakov and Ivanov, 2011;Yablokov et al, 2017).…”

“…Yablokov et al used a modified construct of b 5 covalently attached through an NHS linkage to a gold SPR chip to directly monitor the interactions between b 5 and various human CYP isoforms, including both CYP's whose activity was allosterically regulated by b 5 and those whose activity was unchanged in the presence of b 5 (Yablokov et al, 2017). Interestingly, they determined that the CYP-b 5 interactions fell into two classes: those that were enthalpy driven and those that were entropy driven.…”

“…Requires exogenous fluorophore with high quantum yield CYP, GST Greinert et al, 1979Gut et al, 1985;Schwarz et al, 1993;Gorovits and Horowitz, 1995;Lim et al, 1995;Lakowicz, 1999 , 1999, 2001Kuznetsov et al, 2004;Shimada et al, 2005;Pearson et al, 2006;Archakov and Ivanov, 2011;Martin et al, 2015;Yablokov et al, 2017 Quartz crystal microbalance conductometric Davydov et al, 2013b;Spera et al, 2013 X-ray crystallography with traditional site-directed mutagenesis techniques to obtain answers to structural questions that might not be readily available by either technique alone. X-ray crystallography has also been useful for dissecting the protein-protein interactions of another CYP electron transfer partner, b 5 .…”

Cytochrome b5 enhances androgen synthesis by rapidly reducing the CYP17A1 oxy‐complex in the lyase step

“…We observed that Cyt-b 5 reduces oxy-ferrous CYP17A1 10-fold faster than CPR, with the rate similar to that observed in a ternary complex of all three proteins. Keywords: androgen biosynthesis; cytochrome b5; cytochrome P450; Nanodisc Cytochrome b 5 (Cyt b5) is a small heme protein known to be involved in many reactions mediated by cytochromes P450 [1], and its effect can be stimulatory or inhibitory [2]. Despite decades of work, the role of Cyt b5 in steroid hormone synthesis is still not well understood.…”