Zocher Georg, Winkler Robert, Hertweck Christian, Schulz Georg E
Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität, Albertstrasse 21, 79104 Freiburg im Breisgau, Germany.
J Mol Biol. 2007 Oct 12;373(1):65-74. doi: 10.1016/j.jmb.2007.06.014. Epub 2007 Jun 9.
Nitro groups are found in a number of bioactive compounds. Most of them arise by a stepwise mono-oxygenation of amino groups. One of the involved enzymes is AurF participating in the biosynthesis of aureothin. Its structure was established at 2.1 A resolution showing a homodimer with a binuclear manganese cluster. The enzyme preparation, which yielded the analyzed crystals, showed activity using in vitro and in vivo assays. Chain fold and cluster are homologous with ribonucleotide reductase subunit R2 and related enzymes. The two manganese ions and an iron content of about 15% were established by anomalous X-ray diffraction. A comparison of the cluster with more common di-iron clusters suggested an additional histidine in the coordination sphere to cause the preference for manganese over iron. There is no oxo-bridge. The substrate p-amino-benzoate was modeled into the active center. The model is supported by mutant activity measurements. It shows the geometry of the reaction and explains the established substrate spectrum.
硝基存在于许多生物活性化合物中。它们大多通过氨基的逐步单加氧作用产生。其中一种涉及的酶是参与金霉素生物合成的AurF。其结构在2.1埃分辨率下得以确定，显示为具有双核锰簇的同型二聚体。产生用于分析的晶体的酶制剂，在体外和体内试验中均表现出活性。链折叠和簇与核糖核苷酸还原酶亚基R2及相关酶同源。通过反常X射线衍射确定了两个锰离子和约15%的铁含量。将该簇与更常见的二铁簇进行比较表明，配位球中有一个额外的组氨酸导致对锰而非铁的偏好。不存在氧桥。底物对氨基苯甲酸被模拟到活性中心。该模型得到突变体活性测量的支持。它展示了反应的几何结构并解释了已确定的底物谱。
