title: Thermodynamics of interactions between mammalian cytochromes P450 and b5.
abstract: 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.
authors.affiliation: Institute of Biomedical Chemistry, Pogodinskaya Str. 10, Bldg 8, Moscow 119121, Russia. Electronic address: evgeyablokov1988@mail.ru.
authors.forename: Evgeny
authors.initials: E
authors.lastname: Yablokov
authors.affiliation: Institute of Biomedical Chemistry, Pogodinskaya Str. 10, Bldg 8, Moscow 119121, Russia.
authors.forename: Anna
authors.initials: A
authors.lastname: Florinskaya
authors.affiliation: Institute of Biomedical Chemistry, Pogodinskaya Str. 10, Bldg 8, Moscow 119121, Russia.
authors.forename: Alexei
authors.initials: A
authors.lastname: Medvedev
authors.affiliation: Institute of Bioorganic Chemistry, Kuprevicha Str. 5/2, Minsk 220141, Belarus.
authors.forename: Gennady
authors.initials: G
authors.lastname: Sergeev
authors.affiliation: Institute of Bioorganic Chemistry, Kuprevicha Str. 5/2, Minsk 220141, Belarus.
authors.forename: Natallia
authors.initials: N
authors.lastname: Strushkevich
authors.affiliation: Institute of Bioorganic Chemistry, Kuprevicha Str. 5/2, Minsk 220141, Belarus.
authors.forename: Alexander
authors.initials: A
authors.lastname: Luschik
authors.affiliation: Institute of Bioorganic Chemistry, Kuprevicha Str. 5/2, Minsk 220141, Belarus.
authors.forename: Tatsiana
authors.initials: T
authors.lastname: Shkel
authors.affiliation: Institute of Bioorganic Chemistry, Kuprevicha Str. 5/2, Minsk 220141, Belarus.
authors.forename: Irina
authors.initials: I
authors.lastname: Haidukevich
authors.affiliation: Institute of Bioorganic Chemistry, Kuprevicha Str. 5/2, Minsk 220141, Belarus.
authors.forename: Andrei
authors.initials: A
authors.lastname: Gilep
authors.affiliation: Institute of Bioorganic Chemistry, Kuprevicha Str. 5/2, Minsk 220141, Belarus.
authors.forename: Sergey
authors.initials: S
authors.lastname: Usanov
authors.affiliation: Institute of Biomedical Chemistry, Pogodinskaya Str. 10, Bldg 8, Moscow 119121, Russia.
authors.forename: Alexis
authors.initials: A
authors.lastname: Ivanov
mesh_terms: D000495:Allosteric Site; D000818:Animals; D015374:Biosensing Techniques; D002417:Cattle; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry*; D015786:Cytochromes b5 / Q000737:chemistry*; D004926:Escherichia coli / Q000378:metabolism; D006736:Horses; D006801:Humans; D007700:Kinetics; D011485:Protein Binding; D025941:Protein Interaction Mapping; D013816:Thermodynamics; D015262:Xenobiotics / Q000737:chemistry
chemical_list: D015262:Xenobiotics; D015786:Cytochromes b5; D003577:Cytochrome P-450 Enzyme System
keywords: Cytochrome P450; Cytochrome b5; Optical biosensor; Protein-protein interactions; SPR; Thermodynamics