ABSTRACT: The interaction sites for protein partners, cytochrome P450 2B4 (d-2B4) and NADPH: cytochrome P450 reductase (d-Fp), have
been identified. These proteins form complexes during their functioning. Nonspecific covalent cross-linking of the d-2B4 complexes
with d-Fp in the Emulgen 913 monomerized system was achieved by 4,4′- dithiobis-phenyl azide. Covalently cross-linked peptides
of this complex were identified by ESI-MS/MS. Several binding sites have been identified for these proteins. Based on these
sites a model for intermolecular interaction between these proteins has been proposed. This model includes 5 contact sites
on d-2B4 for d-Fp (stabilized by the cross-linker); these include the following pairs of corresponding peptides of d-2B4 and
d-Fp: 1) d-2B4324–336 and d-Fp570–585; 2) d-2B4423–433 and d-Fp102–109; 3) d-2B4327–336 and d Fp452–464; 4) d-2B4192–197 and d-Fp456–464; 5) d-2B4134–139 and d-Fp406–425. In the two last cases d-Fp peptides are located in the interdomain cleft and stabilize the protein-protein complex via the
cross-linker and so the d 2B4/d-Fp complex formation by these sites may involve amino acid residues of the peptides d-Fp456–464 and d-Fp406–425, which surround the interdomain cleft.
Biochemistry (Moscow) Supplement Series B Biomedical Chemistry 04/2012; 3(4):361-371.