RUI: Structure and Catalytic Mechanism of Plant Carbonic Anhydrase

罗利特博士将分离和纯化碳酸酐酶，这种酶被认为是玉米等重要物种的一种酶。一旦分离出纯形式，他将使用紫外可见光谱学和强大的x射线吸收技术检查酶和几种实验室修饰衍生物的结构。Rowlett博士还建议详细研究植物碳酸酐酶的催化作用，使用核磁共振和停流光谱方法，这些方法能够在其作用机制中挑选出单个化学步骤。虽然动物来源的碳酸酐酶是众所周知的，但对植物碳酸酐酶的了解却很少，而且所知的很少表明植物酶在进化上不同于动物来源的碳酸酐酶。因此，植物碳酸酐酶的表征是非常重要的，有两个原因。首先，植物和动物碳酸酐酶可能是自然界中为数不多的从不同起源进化到具有相同功能的酶对之一（趋同进化）。通过比较这些趋同进化的酶的结构，将有可能区分负责化学催化的蛋白质结构的基本和非基本特征。其次，研究植物碳酸酐酶的催化能力可能有助于解决植物碳酸酐酶在光合作用中的确切功能，这一功能目前尚不清楚，主要是因为缺乏有关酶催化能力的基本信息。

Dr. Rowlett will isolate and purify carbonic anhydrase, an enzyme thought to be important species such as corn. Once isolated in pure form, he will examine the structure of the enzyme and several laboratory-modified derivatives using UV-visible spectroscopy, and powerful X-ray absorption techniques. Dr. Rowlett also proposed to investigate the catalytic role of plant carbonic anhydrase in detail using nuclear magnetic resonance and stopped-flow spectroscopy methods which are capable of picking apart individual chemical steps in their mechanism of action. %%% Although carbonic anhydrases of animal origin are well-known, plant carbonic anhydrases are poorly understood, and what little is known indicates that the plant enzyme is evolutionarily distinct from carbonic anhydrases of animal origin. Thus, the characterization of plant carbonic anhydrases is highly significant, for two reasons. First, plant and animal carbonic anhydrase may represent one of a few pairs of enzymes in nature which have evolved from different origins to arrive at an identical function (convergent evolution). By comparing the structures of such convergently evolved enzymes, it will likely be possible to distinguish the essential and nonessential features of protein structure responsible for chemical catalysis. Second, the study of the catalytic ability of plant carbonic anhydrase may help resolve the exact function of plant carbonic anhydrase in photosynthesis, a function that is currently unknown, primarily because of a lack of fundamental information about the catalytic ability of the enzymes.