In view that mature myeloperoxidase molecule consists of two identical MPO monomers bridged by a disulfide bond we regarded the overall structure of the complex “FIIa-CP-MPO-MPO-CP-FIIa” as a hexamer. Our models for this hexameric structure were proposed on the basis of 3F9P structure (MPO-MPO) (Carpena et al. 2008 ) from the PDB database (http://rcsb.org) and published structures (Samygina et al. 2013 (link); Sokolov et al. 2015b (link)) using PyMOL (Schrödinger LLC 2020), MODELLER (Eswar et al. 2008 ), and GROMACS (Abraham et al. 2015 (link)) software. Glycosylation was constructed using the Glycamgmml software toolkit. Docking was performed using hdocklite, while only FIIa were considered as mobile molecules. Further, from all possible FIIa positions, only those that are sterically compatible with the glycosylation of CP-MPO were selected; it was also assumed that the binding sites of both FIIa molecules are symmetric in the heterohexamer structure. The resulting structures were used for the theoretical calculation of SANS spectra. Theoretical SANS spectra were calculated using the CRYSON programs from the ATSAS package (Franke et al. 2017 (link)).