Citric acid cycle porphyrin synthesis

Pyridoxal phosphate is a required coenzyme for many enzyme-catalyzed reactions. Most of these reactions are associated with the metabolism of amino acids, including the decarboxylation reactions involved in the synthesis of the neurotransmitters dopamine and serotonin. In addition, pyridoxal phosphate is required for a key step in the synthesis of porphyrins, including the heme group that is an essential player in the transport of molecular oxygen by hemoglobin. Finally, pyridoxal phosphate-dependent reactions link amino acid metabolism to the citric acid cycle (chapter 16). 

In addition to its role in energy generation, the citric acid cycle also plays an important role in several biosynthetic processes, such as gluconeogenesis, amino acid synthesis, and porphyrin synthesis. 

The synthesis of 5-aminolevulinate requires succinyl CoA, an intermediate in the citric acid cycle, which occurs in the mitochondrial matrix. Thus it makes sense to have the first step in porphyrin biosynthesis occur in the matrix. 

A. The Measurement of Isotopes. B. The Synthesis and Degradation of Labeled Compounds (Including. Application to Metabolic Studies) Monosaccharides and Polysaccharides Citric -Acid Cycle Intermediates Glycolic, Glyoxylic and Oxalic Acids Purines and Pyrimidines Porphyrins Amino. Acids and Proteins Steroids Methylated Compounds and Derivatives Sulfur Compounds Fatty. Acids Phospholipids Coenzymes lodinatftd Compounds Intermediates of Photosynthesis 0 -Labeled Phosphorus Compound. . 

The citric acid cycle (also known as the tricarboxylic acid cycle, TCA cycle, Krebs cycle) oxidizes acetyl CoA in mitochondria. The cycle produces CO2, NADH and FADH2. The NADH and FADH2 enter oxidative phosphorylation, where they are oxidized to NAD+ and FAD, ready to be used in the citric acid cycle again. The citric acid cycle is also important in some biosynthetic processes such as lipid synthesis, amino acid synthesis, porphyrin synthesis and gluconeogenesis. 

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