Equivalence of the projected structure of thin catalase crystals preserved for electron microscopy by negative stain, glucose or embedding in the presence of tannic acid.
Equivalence of the projected structure of thin catalase crystals preserved for electron microscopy by negative stain, glucose or embedding in the presence of tannic acid.
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通过负染色、葡萄糖或在单宁酸存在下包埋而保存用于电子显微镜的薄过氧化氢酶晶体的投影结构的等效性。
DOI：
10.1016/0022-2836(83)90113-4
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发表时间：
1983
影响因子：
5.6
通讯作者：
S. Edelstein
中科院分区：
文献类型：
--
作者：
C. Akey;S. Edelstein
薄晶体的牛肝过氧化氢酶已检查了电子显微镜下的各种保存程序。在本研究的第一部分中，从单宁酸中嵌入的微晶体薄片中获得了三个主要投影的显微照片。计算机重建证实了p212121的空间组分配，并允许将过氧化氢酶四聚体的包装排列推断到约20的分辨率Å。这些结果证实了Unwin（1975）在一个投影的分子模型的基础上提出的这种晶体形式的堆积模型。在本研究的第二部分，比较了薄晶体在不同保存介质中的投影结构。通过与未包埋的、阴性染色的薄血小板晶体直接比较，证实了在单宁酸存在下包埋的晶体的阴性对比。此外，在20 Å分辨率下，观察到负染色晶体的结构与保存在葡萄糖中的晶体血小板的结构之间的良好一致性，并通过低剂量方法进行了检查，而Taylor（1978）发表的关于嵌入在薄冰层中的晶体的数据也有一定程度的一致性。单宁酸也被发现是保存过氧化氢酶晶体的合适介质，通过电子衍射判断其分辨率为3.7 Å。总的来说，我们证明了从嵌入单宁酸的过氧化氢酶晶体薄片中获得的投影可以提供可靠的，负对比的蛋白质结构表示到20 Å分辨率。因此，晶体切片的检查可以为蛋白质晶体的x射线晶体学研究提供有用的辅助，晶体薄片的三维重建最终应该是可能的。
Thin crystals of beef liver catalase have been examined by electron microscopy following various preservation procedures. In the first part of this investigation, micrographs of three principal projections were obtained from thin sections of micro-crystals embedded in the presence of tannic acid. Computer reconstructions confirmed the space group assignment ofP212121and permitted the packing arrangement of the catalase tetramers to be deduced to a resolution of about 20 Å. These results corroborate the packing model for this crystal form proposed by Unwin (1975) on the basis of molecular modeling of one projection. In the second part of this investigation, the projected structures of the thin crystals in various preserving media were compared. The negative contrasting of crystals embedded in the presence of tannic acid was confirmed by direct comparison with nonembedded, negatively stained thin platelet crystals. In addition, good agreement at 20 Å resolution was observed between the structure of negatively stained crystals and the structure of crystal platelets preserved in glucose and examined by lowdose methods, while moderate agreement was established with the published data of Taylor (1978) for crystals embedded in thin ice films. Tannic acid alone was also found to serve as a suitable medium for preserving catalase crystals to a resolution of 3.7 Å as judged by electron diffraction. Overall, we demonstrate that projections obtained from thin sections of catalase crystals embedded in the presence of tannic acid can provide a reliable, negatively contrasted representation of the protein structure to 20 Å resolution. Examination of sectioned crystals could thus provide a useful adjunct to X-ray crystallographic studies of protein crystals and three-dimensional reconstruction of crystal thin sections should ultimately be possible.
影响因子：
5.6
作者：
MURTHY, MRN;REID, TJ;ROSSMANN, MG
通讯作者：
ROSSMANN, MG
影响因子：
5.6
作者：
Stewart,M
通讯作者：
Stewart,M