PROKARYOTIC CARBONIC ANHYDRASE

描述：碳酸酐酶是一种含锌的酶， CO的可逆水合作用，在人体中普遍存在， 参与各种代谢功能。 它有助于在 释放出以HCO 3形式储存的CO-如在红细胞和 CO2跨膜扩散。 它也参与了 分泌液如眼液;实际上，碳酸酐酶抑制剂 用于治疗青光眼。 碳酸酐酶的研究进展 原核生物是罕见的，主要局限于光养生物， 为光合作用提供二氧化碳。 最近，一类新的碳 脱水酶（g类）是在严格厌氧条件下发现的。 产甲烷古菌嗜热甲烷八叠球菌 结构与人类酶的特征截然不同。 它 假设g碳酸酐酶在生物体内具有新的作用， 不同的非光合需氧菌和厌氧菌的生理学 微生物和细菌领域。 这一广泛而长期的目标 项目是确定分布和生理功能， 碳酸酐酶在不同的原核生物中。 该应用程序有三个 具体目的：（1）确定g碳酸酐酶在 选择生理学和遗传学上不同的原核生物。 （二） 测定了碳酸酐酶的生理功能。 嗜热菌在乙酸发酵的途径甲烷和CO2。 （三） 确定原型g碳酸酐酶的催化机制 从麻省嗜热菌 这些目标将通过整合基因， 生物化学和生物物理研究方法。 预期结果将： (i)更好地评估原核生物中碳酸酐酶的程度，（ii） 鉴定自然界中碳酸酐酶的新生理功能， 和（iii）提供了新的见解的催化机制的所有碳 脱水酶，特别是G类。

DESCRIPTION: Carbonic anhydrase is a zinc-containing enzyme which catalyzes the reversible hydration of CO and is ubiquitous in humans where the enzyme participates in an assortment of metabolic functions. It facilitates in the liberation of CO stored in the form of HCO3- as in red cells and in the diffusion of CO2 across membranes. It is also involved in the formation of secretory fluids such as ocular fluid; indeed, carbonic anhydrase inhibitors are used to treat glaucoma. Past reports of carbonic anhydrase in procaryotes have been rare and largely confined to phototrophs where enzyme supplies CO2 for photosynthesis. Recently, a new class of carbonic anhydrase (the g class) was discovered in the strictly anaerobic methane-producing archaeon Methanosarcina thermophila with a crystal structure strikingly distinct from the well-characterized human enzymes. It is hypothesized that the g carbonic anhydrases have novel roles in the physiology of diverse nonphotosynthetic aerobes and anaerobes from the Archaea and Bacteria domains. The broad, long-term objective of this project is to determine the distribution and physiological function of carbonic anhydrases in diverse procaryotes. This application has three specific aims: (1) Ascertain the occurrence of g carbonic anhydrases in selected physiologically and phylogenetically diverse procaryotes. (2) Determine the physiological function of the carbonic anhydrase from M. thermophila in the pathway of acetate fermentation to methane and CO2. (3) Determine the catalytic mechanism of the prototypic g carbonic anhydrase from M. thermophila. These goals will be achieved by integrating genetic, biochemical and biophysical research methods. The results are expected to: (i) better assess the extent of carbonic anhydrases in procaryotes, (ii) identify novel physiological functions for carbonic anhydrases in nature, and (iii) provide new insights into the catalytic mechanism of all carbonic anhydrases and the g class in particular.