Catalytic and Regulatory Properties of Hybrid ATCases Formefrom Native and Genetically Reconstructed Subunits of Divergent Bacteria

不同生物，特别是肠杆菌的天冬氨酸转甲氨基酰化酶（ATCases）非常相似，可以在类似的三级结构域组织，并在类似的四级聚集体中组装。然而，它们在催化性能和变构反应方面有所不同。不同的基因间融合已经从细菌顺胞和仓鼠cDNA克隆中进行，它们的特性正在进行中。催化链和调控链的序列已经确定。这些将被比较，希望有足够数量的序列：函数比较将允许演绎关键结构/函数关系。位点特异性诱变将被执行，目的是阐明这些催化和调节多肽的每个片段的功能。单克隆抗体将用于比较不同物种的酶的表面结构。与x射线晶体学家的合作将提供有趣的突变改变蛋白质的明确结构信息。对于这类研究来说，这是一个极好的模型系统，怀尔德博士过去的工作使他有资格从事这项研究。

The Aspartate transcarbamoylases (ATCases) of divergent organisms, and in particular of enterobacteria, are sufficiently similar to organize in comparable tertiary domains and to assemble in similar quaternary aggregates. Nevertheless, they differ from each other by their catalytic properties and allosteric responses. Various intergenic fusions have been carried out from bacterial cistrons and hamster cDNA clones and their characterization is underway. The sequences of catalytic and regulatory chains have been determined. These will be compared in the hope that a sufficient number of sequence: function comparisons will permit deduction of critical structure/function relationships. Site specific mutagenesis will be performed aimed at elucidating the function of each segment of these catalytic and regulatory polypeptides. Monoclonal antibodies will be used to compare surface structures of the enzyme from different species. Collaboration with x-ray crystallographers should provide definitive structural information of interesting mutationally altered proteins. This is an excellent model system for such studies and Dr. Wild's past work makes him uniquely qualified for what is proposed.