2Orekhovich Institute of Biomedical Chemistry, Russian Academy of Medical Sciences, ul. Pogodinskaya 10, 119121 Moscow, Russia; fax: (495) 245-0857
* To whom correspondence should be addressed.
Received October 15, 2008; Revision received December 4, 2008
In this work, the diameters of protein complexes formed upon interaction of ceruloplasmin (CP) with lactoferrin (LF) and myeloperoxidase (MPO) were determined. Gage dependence of the diameter of protein particles (myoglobin, albumin, LF, CP, MPO, aldolase, ferritin) on their molecular mass logarithm was calculated. The diameter of a complex formed upon mixing CP and LF was 8.4 nm, which is in line with the radius of gyration obtained previously when the 1CP–1LF complex was studied by small-angle X-ray scattering. The diameter of a complex formed upon interaction of CP with MPO is 9.8 nm, corresponding to the stoichiometry 2CP : 1MPO. The diameter of a complex formed when LF is added to the 2CP–1MPO complex is 10.7 nm. The latter is consistent with the notion of a pentameric structure 2LF–2CP–1MPO with molecular mass of about 585 kDa.
KEY WORDS: ceruloplasmin, lactoferrin, myeloperoxidase, protein–protein interaction, photon correlation spectroscopy