Koolstoffase

Koolstoffase is a term used primarily in Dutch-language biochemistry to denote enzymes that act on carbon-containing substrates or facilitate carbon dioxide metabolism. It is not a single enzyme but an umbrella category that overlaps with established enzyme classes such as carboxylases, decarboxylases, and carbonic anhydrases. In English-language literature, scientists typically use specific class names rather than a general "koolstoffase" label.

Functions of koolstoffases include catalyzing carboxylation, which adds CO2 to substrates, and decarboxylation, which removes CO2. They also mediate the rapid interconversion between carbon dioxide and bicarbonate in physiological fluids, a reaction important for pH regulation and carbon metabolism in many organisms.

Examples of enzymes that would be categorized under koolstoffase, depending on context, include carbonic anhydrase (interconverts CO2 and water with bicarbonate and protons), acetyl-CoA carboxylase (carboxylates acetyl-CoA to malonyl-CoA in fatty acid synthesis), and RuBisCO (carboxylates ribulose-1,5-bisphosphate in the Calvin cycle of photosynthesis). Other carboxylases such as pyruvate carboxylase and propionyl-CoA carboxylase participate in anaplerotic CO2 fixation. Pyruvate decarboxylase catalyzes CO2 removal from pyruvate in certain fermentation processes. Carbon monoxide dehydrogenase can catalyze CO2 reduction to CO in anaerobic microbial pathways.

Structure and cofactors vary among koolstoffases. Carbonic anhydrases commonly require zinc ions; biotin serves as a cofactor for many carboxylases, while others rely on magnesium, flavin, or metal-sulfur clusters.

Biological and practical relevance is broad, spanning core carbon metabolism, photosynthesis, and biotechnological approaches to CO2 fixation. The term koolstoffase is more common in Dutch texts; precise usage typically relies on established names such as carboxylase, decarboxylase, or carbonic anhydrase.