Thermodynamics of interactions between mammalian cytochromes P450 and b5

• Published in: Archives of biochemistry and biophysics 2017-04, Vol.619, p.10-15
• Main Authors: Yablokov, Evgeny, Florinskaya, Anna, Medvedev, Alexei, Sergeev, Gennady, Strushkevich, Natallia, Luschik, Alexander, Shkel, Tatsiana, Haidukevich, Irina, Gilep, Andrei, Usanov, Sergey, Ivanov, Alexis
• Format: Article
• Language: English
• Subjects: Allosteric Site; Animals; Biosensing Techniques; Cattle; Cytochrome b5; Cytochrome P-450 Enzyme System - chemistry; Cytochrome P450; Cytochromes b5 - chemistry; Escherichia coli - metabolism; Horses; Humans; Kinetics; Optical biosensor; Protein Binding; Protein Interaction Mapping; Protein-protein interactions; SPR; Thermodynamics; Xenobiotics - chemistry
• ISSN: 0003-9861; 1096-0384
• DOI: 10.1016/j.abb.2017.02.006

Cytochromes P450 (CYPs) play an important role in the metabolism of xenobiotics and various endogenous substrates. Being a crucial component of the microsomal monooxygenase system, CYPs are involved in numerous protein-protein interactions. However, mechanisms underlying molecular interactions between components of the monooxygenase system still need better characterization. In this study thermodynamic parameters of paired interactions between mammalian CYPs and cytochromes b5 (CYB5) have been evaluated using a Surface Plasmon Resonance (SPR) based biosensor Biacore 3000. Analysis of 18 pairs of CYB5-CYP complexes formed by nine different isoforms of mammalian CYPs and two isoforms of human CYB5 has shown that thermodynamically these complexes can be subdivided into enthalpy-driven and entropy-driven groups. Formation of the enthalpy-driven complexes was observed in the case of microsomal CYPs allosterically regulated by CYB5 (CYB5A-CYP3A4, CYB5A-CYP3A5, CYB5A-CYP17A1). The entropy-driven complexes were formed when CYB5 had no effect on the CYP activity (CYB5A-CYP51A1, CYB5A-CYP1B1, CYB5B-CYP11A1). Results of this study suggest that such interactions determining protein clustering are indirectly linked to the monooxygenase functioning. Positive ΔH values typical for such interactions may be associated with displacement of the solvation shells of proteins upon clustering. CYB5-CYP complex formation accompanied by allosteric regulation of CYP activity by CYB5 is enthalpy-dependent. •Recombinant Cytochromes P450 (CYP) form complexes with cytochrome b5 (CYB5).•There are enthropy- and enthalpy-driven paired CYP-CYB5 complexes.•In enthalpy-driven complexes CYB5 acts as an allosteric regulator.