Search results
Results From The WOW.Com Content Network
Overview of the citric acid cycle. The citric acid cycle—also known as the Krebs cycle, Szent–Györgyi–Krebs cycle, or TCA cycle (tricarboxylic acid cycle) [1] [2] —is a series of biochemical reactions to release the energy stored in nutrients through the oxidation of acetyl-CoA derived from carbohydrates, fats, proteins, and alcohol.
The matrix is host to a wide variety of metabolites involved in processes within the matrix. The citric acid cycle involves acyl-CoA, pyruvate, acetyl-CoA, citrate, isocitrate, α-ketoglutarate, succinyl-CoA, fumarate, succinate, L-malate, and oxaloacetate. [2] The urea cycle makes use of L-ornithine, carbamoyl phosphate, and L-citrulline. [4]
To fully oxidize the equivalent of one glucose molecule, two acetyl-CoA must be metabolized by the Krebs cycle. Two low-energy waste products, H 2 O and CO 2, are created during this cycle. [12] [13] The citric acid cycle is an 8-step process involving 18 different enzymes and co-enzymes.
Spatial movements occur between mitochondria and cytosol and chemical transformations create various Krebs cycle intermediates. In all variants, pyruvate is imported into the mitochondrion for processing through part of the Krebs cycle. In addition to pyruvate, alpha-ketoglutarate may also be imported.
Pyruvate oxidation is the step that connects glycolysis and the Krebs cycle. [4] In glycolysis, a single glucose molecule (6 carbons) is split into 2 pyruvates (3 carbons each). Because of this, the link reaction occurs twice for each glucose molecule to produce a total of 2 acetyl-CoA molecules, which can then enter the Krebs cycle.
The proportion of cell volume that is cytosol varies: for example while this compartment forms the bulk of cell structure in bacteria, [9] in plant cells the main compartment is the large central vacuole. [10] The cytosol consists mostly of water, dissolved ions, small molecules, and large water-soluble molecules (such as proteins).
The function of fumarase in the citric acid cycle is to facilitate a transition step in the production of energy in the form of NADH. [12] In the cytosol, the enzyme functions to metabolize fumarate, which is a byproduct of the urea cycle as well as amino acid catabolism. Studies have revealed that the active site is composed of amino acid ...
It functions as a pace-making enzyme in the first step of the citric acid cycle (or Krebs cycle). [5] Citrate synthase is located within eukaryotic cells in the mitochondrial matrix, but is encoded by nuclear DNA rather than mitochondrial. It is synthesized using cytoplasmic ribosomes, then transported into the mitochondrial matrix.