Roles of Additives and Precipitants in Crystallization of Calcium- and Integrin-Binding Protein

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• 作者：Bryan W. Berger ; Chad J. Blamey ; Ulhas P. Naik ; Brian J. Bahnson ; and Abraham M. Lenhoff
• 刊名：Crystal Growth & Design
• 出版年：2005
• 出版时间：July 2005
• 年：2005
• 卷：5
• 期：4
• 页码：1499 - 1507
• 全文大小：364K
• 年卷期：v.5,no.4(July 2005)
• ISSN：1528-7505

文摘

The interactions leading to crystallization of calcium- and integrin-binding protein (CIB), a novelCa²⁺ binding protein, were characterized in terms of osmotic second virial coefficients, B₂₂, measured byself-interaction chromatography. In particular, the role of additives such as alkanediols or DMSO in improvingcrystal growth in the presence of sodium malonate, sodium formate, and sodium acetate was investigated. Short-chain alkane-1,n-diols were found to be effective in a range of 10-20% (v/v) in preventing CIB precipitation at thehigh sodium formate concentrations necessary for crystallization, whereas for alkane-1,2-diols longer chains werenecessary, although at concentrations less than 5% (v/v). In both cases, significant improvement in protein crystalgrowth and suppression of precipitation were observed. Isothermal titration calorimetry measurements indicatethat the differences in alkanediol specificity are a result of interactions with hydrophobic regions on the proteinsurface, which in turn depend on chain length and structure. Overall, our investigation of the protein-proteininteractions provides valuable insight into the modulating roles that additives play, which is essential to developingrational approaches to protein crystallization. Our work also demonstrates the applicability of self-interactionchromatography to studying crystallization of novel proteins, particularly those that may otherwise be difficult tocrystallize due to poor solubility.