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The Role of Carbonic Anhydrase in Photosynthesis

The Role of Carbonic Anhydrase in Photosynthesis Carbonic anhydrase (CA, EC 4.2.1.1) is a zinc-containing metalloenzyme that catalyzes the interconversion of C02 and HC03- in many organisms (Equa­ tion 1). 1. 0066-4294/94/0601-0369$05.00 BADGER & PRICE In the hydration reaction, C02 reacts with a Zn-OH intermediate at the active site of the enzyme. In the reverse dehydration direction, HC03 reacts with Zn-H20. This reaction has been studied cxtensively, particularly with CA enzymes from animal sources. Recent reviews cover extensively the mecha­ nistic functioning and evolutionary diversity of this enzyme (20, 94, 107). - Carbonic anhydrase is required in biological systems because the un­ catalyzed interconversion between C02 and HC03- is slow when compared to thc flux rates between these specics, which may bc required in living cells. For example, in a higher plant chloroplast, the rate of photosynthesis may ap­ proach 300 /lmol mg ChC 1 h-I. This is about 2.8 mM s-I, assuming a chloro­ I plast volume of 30 /-LI mg ChC . The uncatalyzed first-order rate constant for the conversion of C02 to HC03- is about 0.05 s I at 25 DC and pH 8 (57). Thus at present atmospheric C02 levels (350 ppm, leading to a chloroplast [C02] of about 8 /lM) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Annual Review of Plant Biology Annual Reviews

The Role of Carbonic Anhydrase in Photosynthesis

Annual Review of Plant Biology , Volume 45 (1) – Jun 1, 1994

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References (84)

Publisher
Annual Reviews
Copyright
Copyright 1994 Annual Reviews. All rights reserved
Subject
Review Articles
ISSN
1040-2519
DOI
10.1146/annurev.pp.45.060194.002101
Publisher site
See Article on Publisher Site

Abstract

Carbonic anhydrase (CA, EC 4.2.1.1) is a zinc-containing metalloenzyme that catalyzes the interconversion of C02 and HC03- in many organisms (Equa­ tion 1). 1. 0066-4294/94/0601-0369$05.00 BADGER & PRICE In the hydration reaction, C02 reacts with a Zn-OH intermediate at the active site of the enzyme. In the reverse dehydration direction, HC03 reacts with Zn-H20. This reaction has been studied cxtensively, particularly with CA enzymes from animal sources. Recent reviews cover extensively the mecha­ nistic functioning and evolutionary diversity of this enzyme (20, 94, 107). - Carbonic anhydrase is required in biological systems because the un­ catalyzed interconversion between C02 and HC03- is slow when compared to thc flux rates between these specics, which may bc required in living cells. For example, in a higher plant chloroplast, the rate of photosynthesis may ap­ proach 300 /lmol mg ChC 1 h-I. This is about 2.8 mM s-I, assuming a chloro­ I plast volume of 30 /-LI mg ChC . The uncatalyzed first-order rate constant for the conversion of C02 to HC03- is about 0.05 s I at 25 DC and pH 8 (57). Thus at present atmospheric C02 levels (350 ppm, leading to a chloroplast [C02] of about 8 /lM)

Journal

Annual Review of Plant BiologyAnnual Reviews

Published: Jun 1, 1994

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