School of Biological Sciences, The University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia.
MX, Australian Synchrotron, 800 Blackburn Road Clayton, Melbourne, VIC 3168, Australia.
Acta Crystallogr D Struct Biol. 2019 Jul 1;75(Pt 7):670-681. doi: 10.1107/S2059798319009008. Epub 2019 Jul 2.
Two commonly encountered bottlenecks in the structure determination of a protein by X-ray crystallography are screening for conditions that give high-quality crystals and, in the case of novel structures, finding derivatization conditions for experimental phasing. In this study, the phasing molecule 5-amino-2,4,6-triiodoisophthalic acid (I3C) was added to a random microseed matrix screen to generate high-quality crystals derivatized with I3C in a single optimization experiment. I3C, often referred to as the magic triangle, contains an aromatic ring scaffold with three bound I atoms. This approach was applied to efficiently phase the structures of hen egg-white lysozyme and the N-terminal domain of the Orf11 protein from Staphylococcus phage P68 (Orf11 NTD) using SAD phasing. The structure of Orf11 NTD suggests that it may play a role as a virion-associated lysin or endolysin.
在利用 X 射线晶体学确定蛋白质结构的过程中，通常会遇到两个常见的瓶颈：筛选出能够获得高质量晶体的条件，以及在遇到新颖结构时，找到用于实验相位测定的衍生化条件。在这项研究中，将相位测定分子 5-氨基-2,4,6-三碘间苯二甲酸（I3C）添加到随机微种基质筛选中，以在单个优化实验中生成用 I3C 衍生化的高质量晶体。I3C 通常被称为“魔术三角”，它含有一个带有三个结合碘原子的芳香环支架。这种方法被应用于使用 SAD 相位测定法有效地对鸡卵清溶菌酶和葡萄球菌噬菌体 P68 的 N 端结构域（Orf11 NTD）的结构进行相位测定。Orf11 NTD 的结构表明，它可能作为病毒体相关溶菌酶或内溶素发挥作用。
