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  2. Urea cycle - Wikipedia

    en.wikipedia.org/wiki/Urea_cycle

    The urea cycle converts highly toxic ammonia to urea for excretion. [1] This cycle was the first metabolic cycle to be discovered by Hans Krebs and Kurt Henseleit in 1932, [2] [3] [4] five years before the discovery of the TCA cycle. The urea cycle was described in more detail later on by Ratner and Cohen.

  3. Hyperammonemia - Wikipedia

    en.wikipedia.org/wiki/Hyperammonemia

    The metabolic pathways that synthesize urea involve reactions that start in the mitochondria and then move into the cytosol. The process is known as the urea cycle, which comprises several enzymes acting in sequence. It is greatly exacerbated by common zinc deficiency, which raises ammonia levels further. [1]

  4. Urea - Wikipedia

    en.wikipedia.org/wiki/Urea

    Urea is synthesized in the body of many organisms as part of the urea cycle, either from the oxidation of amino acids or from ammonia. In this cycle, amino groups donated by ammonia and L-aspartate are converted to urea, while L-ornithine, citrulline, L-argininosuccinate, and L-arginine act as intermediates. Urea production occurs in the liver ...

  5. Metabolic waste - Wikipedia

    en.wikipedia.org/wiki/Metabolic_waste

    The excretion of urea is called ureotelism. Land animals, mainly amphibians and mammals, convert ammonia into urea, a process which occurs in the liver and kidney. These animals are called ureotelic. [3] Urea is a less toxic compound than ammonia; two nitrogen atoms are eliminated through it and less water is needed for its excretion.

  6. Deamination - Wikipedia

    en.wikipedia.org/wiki/Deamination

    Ammonia is toxic to the human system, and enzymes convert it to urea or uric acid by addition of carbon dioxide molecules (which is not considered a deamination process) in the urea cycle, which also takes place in the liver. Urea and uric acid can safely diffuse into the blood and then be excreted in urine.

  7. Ammonia volatilization from urea - Wikipedia

    en.wikipedia.org/wiki/Ammonia_volatilization...

    Urease is a naturally occurring enzyme that catalyzes the hydrolysis of urea to unstable carbamic acid. Rapid decomposition of carbamic acid occurs without enzyme catalysis to form ammonia and carbon dioxide. [2] [3] The ammonia will likely escape to the atmosphere unless it reacts with water to form ammonium (NH 4 +) according to the following ...

  8. Ammonia - Wikipedia

    en.wikipedia.org/wiki/Ammonia

    The liver converts ammonia to urea through a series of reactions known as the urea cycle. Liver dysfunction, such as that seen in cirrhosis, may lead to elevated amounts of ammonia in the blood (hyperammonemia). Likewise, defects in the enzymes responsible for the urea cycle, such as ornithine transcarbamylase, lead to hyperammonemia.

  9. Ornithine transcarbamylase - Wikipedia

    en.wikipedia.org/wiki/Ornithine_transcarbamylase

    Mutations in the OTC gene can cause Ornithine Transcarbamylase deficiency. It is classified as a urea cycle disorder due to the fact that without proper OTC function ammonia starts to accumulate in the blood. Accumulation of ammonia in the blood is known as hyperammonemia. Although toxic in excess, ammonia is a nitrogen source for the body.