urea comes from the kidney in the body.
where does urea come from in the body?
the kidney
urease is also found in mammals and humans, the presence of urease is considered to be very harmful to mammals due to the production of the toxic ammonia product. however, mammalian cells do not produce urease, in fact, the sources are the various bacteria in the body, specifically in the intestine. european hare (lepus europaeus), a class of mammalia, was discovered to have high urease activity in its large intestine, a part of gastrointestinal tract. previously, other mammals i.e. rats, pigs and rabbits, with postgastric fermentation were detected with lower urease activity compared to european hare. in human kidneys, urea is present in order for everyday functions and is estimated that per day, a healthy adult excretes about 10 to 30 g of urea. other than urea being found in urine, it is also present in sweat, blood serum and stomach. inside the mitochondria of a liver cell, excess ammonia is converted to urea through the urea cycle and if some excess ammonia is still present in the mitochondria, then it gets used up for protein synthesis. there are specific tissues involved during urea processing which are epithelial, extrahepatic and muscle tissues. with the production of ammonia and amino acids, the cell proteins are broken down by proteolytic enzymes already present in the muscle tissue. similarly, identical cell proteins are predicted to convert previously broken down ammonia into urea. once the urea is formed in the liver, it is excreted through urine after passing from bloodstream and the kidneys.
urease
-ornithine is one of the products of the action of the enzyme arginase on -arginine, creating urea. therefore, ornithine is a central part of the urea cycle, which allows for the disposal of excess nitrogen. ornithine is recycled and, in a manner, is a catalyst. first, ammonia is converted into carbamoyl phosphate (). ornithine is converted into a urea derivative at the δ (terminal) nitrogen by carbamoyl phosphate synthetase. another nitrogen is added from aspartate, producing the denitrogenated fumarate, and the resulting arginine (a guanidinium compound) is hydrolysed back to ornithine, producing urea. the nitrogens of urea come from the ammonia and aspartate, and the nitrogen in ornithine remains intact.
ornithine