The Role of Cations and Anions in the Formation of Crystallization Oligomers in Protein Solutions as Revealed by Combination of Small-Angle X-ray Scattering and Molecular Dynamics
Margarita A. Marchenkova,
Petr V. Konarev,
Yuliya V. Kordonskaya,
Kseniia B. Ilina,
Yury V. Pisarevsky,
Alexander V. Soldatov,
Vladimir I. Timofeev,
Mikhail V. Kovalchuk
Affiliations
Margarita A. Marchenkova
A.V. Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics”, Russian Academy of Sciences, 59, Leninskii Prospect, Moscow 119333, Russia
Petr V. Konarev
A.V. Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics”, Russian Academy of Sciences, 59, Leninskii Prospect, Moscow 119333, Russia
Yuliya V. Kordonskaya
National Research Centre “Kurchatov Institute”, 1, Akademika Kurchatova pl., Moscow 123182, Russia
Kseniia B. Ilina
A.V. Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics”, Russian Academy of Sciences, 59, Leninskii Prospect, Moscow 119333, Russia
Yury V. Pisarevsky
A.V. Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics”, Russian Academy of Sciences, 59, Leninskii Prospect, Moscow 119333, Russia
Alexander V. Soldatov
The Smart Materials Research Institute, Southern Federal University, 178/124, Andreya Sladkova Street, Rostov on Don 344090, Russia
Vladimir I. Timofeev
A.V. Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics”, Russian Academy of Sciences, 59, Leninskii Prospect, Moscow 119333, Russia
Mikhail V. Kovalchuk
A.V. Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics”, Russian Academy of Sciences, 59, Leninskii Prospect, Moscow 119333, Russia
As is known from molecular dynamics simulation, lysozyme oligomers in crystallization solutions are most stable when taking into account as many precipitant ions as possible embedded in the corresponding crystal structure. Therefore, the number of precipitant ions associated with crystallographic oligomer models can play a role during the modeling of small-angle X-ray scattering (SAXS) data. This hypothesis has been tested in the present work. As a result, it turned out that the best fit quality to the experimental SAXS data is reached when using oligomers without precipitant ions at all or with embedded chlorine ions. Molecular dynamics (MD) simulation shows that the stability of crystallization oligomers depends on the consideration of anions and cations in oligomer structure. Thus, it is chlorine ions which stabilize dimer and octamers in lysozyme crystallization solution. As SAXS is more sensitive to the role of cations and MD shows the role of anions which are “light” for X-rays, it has been shown that precipitant cations most likely do not bind to monomers, but to already-formed oligomers.
