Kolmoiskarboksyyliryhmä

Kolmoiskarboksyyliryhmä, also known as tricarboxylic acid cycle or Krebs cycle, is a series of chemical reactions used by all aerobic organisms to generate energy from glucose. The cycle is named for its three carboxyl groups and is a key part of cellular respiration. It occurs in the mitochondrial matrix of eukaryotic cells and in the cytoplasm of prokaryotic cells.

The Krebs cycle begins with the condensation of acetyl-CoA with oxaloacetate to form citrate. This reaction is catalyzed by citrate synthase. The cycle then proceeds through a series of oxidation-reduction reactions, which generate NADH, FADH2, and GTP (or ATP in some organisms). The cycle also produces carbon dioxide as a byproduct.

The intermediates of the Krebs cycle serve as precursors for the synthesis of various biomolecules, including amino acids, nucleotides, and lipids. The cycle is tightly regulated to ensure that the supply of intermediates matches the demand for biosynthetic pathways.

The Krebs cycle is highly conserved across different organisms, with minor variations in the enzymes involved. It is a fundamental process in metabolism and plays a crucial role in maintaining cellular homeostasis.