Properties of Carbonic Anhydrase in Chlamydomonas Reinhardtii

点击翻译按钮获取中文摘要

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.