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Novel approach to controlled protein crystallization through ligandation of yttrium cations
Author(s) -
Zhang Fajun,
Zocher Georg,
Sauter Andrea,
Stehle Thilo,
Schreiber Frank
Publication year - 2011
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889811017997
Subject(s) - yttrium , crystallization , protein crystallization , crystallography , phase diagram , crystal structure , crystal (programming language) , molecule , materials science , ion , chemistry , chemical physics , phase (matter) , organic chemistry , programming language , computer science , oxide
Crystal structure determination of macromolecules is often hampered by the lack of crystals suitable for diffraction experiments. This article describes a protocol to crystallize the acidic protein bovine β‐lactoglobulin in the presence of yttrium to yield high‐quality crystals that belong to a new space group. The yttrium ions not only are used to engineer the crystallization, but are an integral part of the crystal lattice and can therefore be used to solve the phase problem using anomalous dispersion methods. Protein crystallization conditions were first optimized using an experimental phase diagram in the protein and salt concentration plane. Crystal growth strongly depends on the position in the phase diagram, and the best crystals grow near the phase transition boundaries. The structure analysis demonstrates the specific binding of yttrium ions to surface‐exposed glutamate and aspartate side chains contributed by different molecules in the crystal lattice. By bridging molecules in this manner, contacts between molecules are formed that enable the formation of a stable crystal lattice. The potential application of this strategy to the crystallization of other acidic proteins is discussed on the basis of the universal features of the phase behavior of these proteins and the interactions induced by multivalent ions.