Zimmerman S A, Ferry J G
Department of Biochemistry & Molecular Biology, Pennsylvania State University, 205 S. Frear Laboratory, University Park, PA 16802, USA.
Curr Pharm Des. 2008;14(7):716-21. doi: 10.2174/138161208783877929.
There are currently five (alpha, beta, gamma, delta, zeta) classes of carbonic anhydrases (CA's) of which the alpha-class from mammalian sources has been studied to a much greater extent compared to the other four classes. Yet, CA's other than the alpha-class are widely distributed in Nature and play important roles in human health, the global carbon cycle, and industrial applications. In aerobic prokaryotes, beta-class CA's are implicated in maintaining internal pH and CO(2)/bicarbonate balances required for biosynthetic reactions. In anaerobic prokaryotes, beta-class CA's are implicated in the transport of CO(2) and bicarbonate across the cytoplasmic membrane that regulates pH and facilitates acquisition of substrates and product removal required for growth. In phototrophic organisms, beta-class CA's are particularly important for transport and concentration of CO(2) and bicarbonate for photosynthesis. The delta- and zeta-classes are proposed to function in marine diatoms to concentrate CO(2) for photosynthesis. Physiological roles for the gamma-class are not as well documented; however, the active site architecture and catalytic mechanism is well understood as are patterns of inhibition by sulfonamides and anions.
目前有五类（α、β、γ、δ、ζ）碳酸酐酶（CA），与其他四类相比，对哺乳动物来源的α类碳酸酐酶的研究要深入得多。然而，除α类之外的碳酸酐酶在自然界中广泛分布，在人类健康、全球碳循环和工业应用中发挥着重要作用。在需氧原核生物中，β类碳酸酐酶参与维持生物合成反应所需的内部pH值以及二氧化碳/碳酸氢盐平衡。在厌氧原核生物中，β类碳酸酐酶参与二氧化碳和碳酸氢盐跨细胞质膜的运输，这种运输调节pH值并促进获取生长所需的底物和产物清除。在光合生物中，β类碳酸酐酶对于光合作用中二氧化碳和碳酸氢盐的运输及浓缩尤为重要。有人提出δ类和ζ类在海洋硅藻中发挥作用，将二氧化碳浓缩用于光合作用。γ类的生理作用记录较少；然而，其活性位点结构和催化机制以及磺胺类药物和阴离子的抑制模式已得到很好的理解。
