Karboksylase

Karboksylase is a general term for enzymes that catalyze the addition of a carboxyl group (COOH) to a substrate. This process is known as carboxylation. Carboxylation reactions are crucial in many biological pathways, including the synthesis of fatty acids, amino acids, and nucleotides. Karboksylases often require a cofactor, such as biotin or cobalamin, to facilitate the transfer of the carboxyl group. These enzymes play vital roles in metabolism and are essential for life.

One well-known example of a karboksylase is acetyl-CoA karboksylase (ACC), which catalyzes the first committed step in fatty acid biosynthesis. ACC adds a carboxyl group to acetyl-CoA, forming malonyl-CoA. Another important karboksylase is pyruvate karboksylase, involved in gluconeogenesis, the synthesis of glucose from non-carbohydrate precursors. This enzyme converts pyruvate to oxaloacetate, a key intermediate in this pathway. The activity of karboksylases can be regulated by various factors, including substrate availability, product inhibition, and hormonal signals, allowing cells to control metabolic flux and maintain homeostasis.