Studies on the Mechanism and Control of Enzyme Action

从大肠杆菌中获得的腺苷琥珀酸合成酶是二聚体，结合三个底物和一个金属离子。从几个角度探讨了合成酶作用的化学机理。参与结合和催化过程的特定氨基酸残基通过化学和变质方法进行了检查。这些研究需要大量的光谱工作来定位观察到的效应。将进行化学和光谱交换研究，以获得结合和催化步骤的时间和顺序的核心问题。正在进行的野生型和突变型酶以及抑制剂存在下的酶的晶体学研究将继续进行。腺苷琥珀酸合成酶参与了从IMP转化AMP的过程。由于其位于代谢途径的开始，作为细胞整体代谢整合的一部分，该酶的催化活性受到许多控制。提出的研究探索存在于酶和代谢物及其结合抑制剂之间的复杂相互作用。拟议的研究将确定效应器，底物和产物结合的顺序和紧密性，将确定酶中催化重要的结构，并将确定和表征沿反应途径发生的中间体。使用x射线晶体学对酶的三维结构的研究将继续进行。

The enzyme adenylosuccinate synthetase obtained from E. coli is dimeric and binds three substrates plus a metal ion. The chemical mechanism of the function of the synthetase is approached from a number of points of view. Specific amino acid residues involved in binding and catalytic processes are examined via chemical and metagenesis approaches. These studies require considerable spectroscopic effort to localize the observed effects. Chemical and spectroscopic exchange studies will be performed to get at central questions of the timing and order of binding and catalytic steps. Ongoing crystallograpic studies of wild type and mutant enzyme as well as enzyme in the presence of inhibitors will be continued. %%% Adenylosuccinate synthetase is involved in the conversion of AMP from IMP. By virtue of its location at the beginning of a metabolic pathway, this enzyme is subject to a number of controls of its catalytic activity as part of the overall metabolic integration of the cell. The proposed research explores the complex interactions which exist between the enzyme and metabolites and inhibitors it binds. The proposed research will identify the order and tightness of binding of effectors, substrates, and products, will identify catalytically important structures in the enzyme, and will identify and characterize intermediates occurring along the reaction pathway. Studies of the three-dimensional structure of the enzyme, using X-ray crystallography, will be continued.