DATA COLLECTION FROM SMALL CRYSTALS OF LARGE ENZYME ACONITASE

使用线粒体（mAc）的晶体学实验是 提供了对活性位点结构、底物结合 并探讨了该[Fe-S]酶的催化机理。 的应用 突变和表达方法，我们已经开发的mAc是 允许关于[Fe-S]簇化学的基本问题， 通过底物和抑制剂结合接近的蛋白质， 聚类设计和工程实验。 正在进行的结构 对7 Fe铁氧还蛋白（FdI）的研究正在确定控制 [Fe-S]簇结构和性质，并提供洞察 无机[Fe-S]核的化学和构象行为 蛋白质环境 mAc是含有[4Fe-4S]的83 kD蛋白质。 簇，直接参与催化。 FdI为13 kD 电子传递蛋白含有[3Fe-4S]和[4Fe-4S]簇。 重组乌头酸酶的晶体在1.8-2.0 E分辨率下结晶， 十万然而，它们不能生长得大于0.3 x 0.1 x 0.05 mm。 为了研究活性位点的关键细节， 小分子和[Fe-S]簇的精确几何形状，它是 需要采集至少2.5 E的数据，最好是2.0-1.8 E.对于mAc晶体，这仅在同步辐射下才可能。 FdI晶体很大，并且具有很好的结晶性。 但为了 对[Fe-S]团簇进行全矩阵最小二乘精修， 有必要收集1.4E分辨率数据，这也 需要同步辐射

Crystallographic experiments with mitochondrial (mAc) are providing insight into the active site structure, substrate binding and catalytic mechanism of this [Fe-S] enzyme. Application of the mutagenesis and expression methods we have developed for mAc is allowing fundamental questions about [Fe-S] cluster chemistry in proteins to be approached through substrate and inhibitor binding and cluster design and engineering experiments. On-going structural studies of a 7Fe ferredoxin (FdI) are defining the factors controlling [Fe-S] cluster structure and properties and providing insight into the chemical and conformational behavior of inorganic [Fe-S] cores in a protein environment. mAc is an 83 kD protein containing a [4Fe-4S] cluster, which participates directly in catalysis. FdI is a 13 kD electron transfer protein containing [3Fe-4S] and [4Fe-4S] clusters. Crystals of recombinant aconitase diffract to 1.8-2.0 E resolution at 100 K. However, they can not be grown larger that 0.3 x 0.1 x 0.05 mm. In order to study the critical details of the active site, the binding of small molecules and the precise geometry of [Fe-S] clusters, it is necessary to acquire data to at least 2.5 E and preferably to 2.0-1.8 E. For mAc crystals this is only possible with synchrotron radiation. FdI crystals are large and diffract very well. However, in order to carry out full matrix least squares refinement of the [Fe-S] clusters, it is necessary to collect data to 1.4 E resolution, and this also requires synchrotron radiation.