Institute for Integrated Cell-Material Sciences, Funai Center, Kyoto University Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
Bioconjug Chem. 2010 Feb 17;21(2):264-9. doi: 10.1021/bc9003052.
Protein assemblies have attracted increasing attention for construction of biohybrid materials. Protein crystals can also be regarded as solid protein assemblies. The present work demonstrates that protein crystals can be employed as porous biomaterials by site-specific modifications of the crystals of recombinant sperm whale myoglobin mutants. The myoglobin crystals of space group P6 provide hexagonal pores consisting of the building blocks of six Mb molecules, which form a pore with a diameter of 40 A. On the basis of the lattice structure of the Mb crystals, we have selected appropriate residues located on the surface of the pores for replacement with cysteine. This enables modification of the pore surface via coupling with maleimide derivatives. We have succeeded in crystallizing the modified Mb mutants, retaining the P6 lattice, and consistently aligning nanosized functional molecules such as fluorescein, eosin, and Ru(bpy)(3) into the hexagonal pores of the Mb crystals. Our strategy for site-specific modification of protein crystal pores is applicable to various protein crystals with porous structures. We believe that modified porous protein crystals will provide attractive candidates for novel solid materials in nanotechnology applications.
蛋白质组装体因其在构建生物杂化材料方面的优势而受到越来越多的关注。蛋白质晶体也可以被视为固体蛋白质组装体。本工作通过对重组抹香鲸肌红蛋白突变体晶体进行定点修饰，证明了蛋白质晶体可用作多孔生物材料。属于空间群 P6 的肌红蛋白晶体提供了由六个 Mb 分子组成的六方孔，形成了一个 40A 的直径的孔。基于 Mb 晶体的晶格结构，我们选择了位于孔表面的合适残基进行半胱氨酸取代。这使得通过与马来酰亚胺衍生物偶联来修饰孔表面成为可能。我们成功地对修饰后的 Mb 突变体进行了结晶，保留了 P6 晶格，并一致地将纳米级功能分子（如荧光素、曙红和 Ru(bpy)(3)）排列到 Mb 晶体的六方孔中。我们对蛋白质晶体孔进行定点修饰的策略适用于具有多孔结构的各种蛋白质晶体。我们相信，修饰后的多孔蛋白质晶体将为纳米技术应用中的新型固体材料提供有吸引力的候选材料。
