Properties of Carbonic Anhydrase in Chlamydomonas Reinhardtii

碳酸酐酶催化两种形式的无机碳，CO2和HCO3的相互转化，这两种形式的无机碳在生理pH值的水介质中占主导地位。在莱茵衣藻（Chlamydomonas reinhardtii）中，一种或多种形式的碳酸酐酶是无机碳获取和浓缩系统的组成部分。这个系统使这些生物能够有效地利用低水平的二氧化碳，否则会限制它们的生长。为了研究碳酸酐酶活性位点的大小亚基之间的物理关系，我们将合成一种碳酸酐酶特异性活性位点定向放射性标记光亲和试剂。作为鉴定和分离生理上重要的细胞内碳酸酐酶的工具，碳酸酐酶的水平太低，目前可用的方法无法轻易识别和量化。本研究将研究莱茵衣藻胞外碳酸酐酶的亚基结构和二硫键还原状态对其催化和抑制剂结合性能的影响。这些研究将有助于理解胞外碳酸酐酶的结构-功能关系，并有助于识别莱茵衣藻细胞有效浓缩无机碳以提供光合作用所需二氧化碳的系统的其他重要组成部分。

The enzyme carbonic anhydrase catalyzes the interconversion of the two forms of inorganic carbon, CO2 and HCO3, which predominate in aqueous media at physiological pH values. In the alga Chlamydomonas reinhardtii, one or more forms of carbonic anhydrase are components of a system for inorganic carbon acquisition and concentration. This system enables these organisms to efficiently utilize CO2 present at low levels, which could otherwise limit their growth. A carbonic anhydrase-specific active site-directed radiolabeled photoaffinity reagent will be synthesized in order to study the physical relationship between the large and small subunits with respect to the active site of the enzyme, and as a tool in the identification and isolation of physiologically important intracellular forms of carbonic anhydrase which are present in levels too low to be readily identified and quantified by currently available methods. This proposal will investigate the relationship between the subunit structure and disulfide bond reduction status on both the catalytic and inhibitor binding properties of the predominant extracellular form of carbonic anhydrase from Chlamydomonas reinhardtii. These studies will contribute to understanding the structure-function relationship of the extracellular carbonic anhydrase, and to the identification of other important components of the system by which Chlamydomonas reinhardtii cells are able to efficiently concentrate inorganic carbon to provide CO2 for photosynthesis.