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Carboxylating Enzymes
EditCarboxylating enzymes catalyze reactions that incorporate inorganic carbon into organic substrates as a carboxyl group. They participate in biosynthetic pathways and carbon-fixation cycles with distinct substrate and energy requirements [1]. Biotin-dependent carboxylases couple ATP-driven activation of bicarbonate to carboxylation of enzyme-bound biotin, followed by transfer of the carboxyl group to an acceptor substrate [2]. Ribulose-1,5-bisphosphate carboxylase/oxygenase fixes carbon dioxide through a different active-site reaction. In bacterial carboxysomes, it is enclosed with carbonic anhydrase in a protein shell that elevates carbon dioxide availability near the enzyme [3]. Carboxylation systems thus combine an organic acceptor-binding site with machinery for inorganic-carbon utilization. Mobile cofactor-bearing regions can connect separate catalytic sites within a single carboxylase assembly [4].
References
- Tobias J. Erb; Carboxylases in Natural and Synthetic Microbial Pathways. Appl. Environ. Microbiol. 2011, 77, 8466-8477. [CrossRef]
- Liang Tong; Structure and Function of Biotin-dependent Carboxylases. Cell. Mol. Life Sci. 2012, 70, 863-891. [CrossRef]
- Benjamin D. Rae; Benedict M. Long; Murray R. Badger; G. Dean Price; Functions, Compositions, and Evolution of the Two Types of Carboxysomes: Polyhedral Microcompartments That Facilitate CO 2 Fixation in Cyanobacteria and Some Proteobacteria. Microbiol. Mol. Biol. Rev. 2013, 77, 357-379. [CrossRef]
- Richard N. Perham; Swinging Arms and Swinging Domains in Multifunctional Enzymes: Catalytic Machines for Multistep Reactions. Annu. Rev. Biochem. 2000, 69, 961-1004. [CrossRef]
