Excess nitrogen, disposal

The result is that the amino groups can be dumped out as alanine (the transamination product of pyruvate). In the liver and kidney, alanine is transaminated to yield pyruvate and glutamate. As in the Cord cycle, the pyruvate is converted to glucose by the liver and is shipped out. The glutamate is fed into the urea cycle-nitrogen disposal system to get rid of the excess nitrogen. 

Urea Is Not the Only Means of Disposing of Excess Nitrogen... 

The organic molecule urea is normally made in your kidneys and excreted in urine to dispose of excess nitrogen. Wohler had produced urea in the laboratory from ammonia and cyanic acid. He showed that it is possible to take lifeless molecules and produce one of the molecules of life in the laboratory. Today, it is possible to synthesize artificially many thousands of complex biomolecules. However, living cells still are the most efficient laboratories, and it can take months or years for chemists to synthesize a large molecule that a cell can make in seconds or minutes. 

Excess nitrogen dioxide and waste material containing this substance should be placed in an appropriate container, clearly labeled, and handled according to your institution s waste disposal guidelines. For more information on disposal procedures, see Chapter 7 of this volume. ... 

If rats are injected with a mixture of amino acids, there is a rapid increase in the liver content of glutamate. This is followed by an increase in acetylglutamate, a consequent increase in carbamoyl phosphate synthase activity and an increase in urea production. If excess amino acids are injected, the liver carbamoyl phosphate synthase becomes saturated with acetylglutamate and ammonia appears in the circulation. Thus regulation of carbamoyl phosphate synthase by N-acetylglutamate appears to be an important factor in the control of nitrogen disposal by the liver. 

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