Biochemistry

Reductive amination is catalyzed by a well-functioning enzyme system that provides amination of a-ketoglutaric or oxaloacetic acid to form glutamic or aspartic acids. COOH 1 COOH 1 1 CH 2 1 +NH3 + 2H — ► c = o 1 1 CH 2 1 • + H 2 O CH-NH 2 1 COOH Oxaloacetic acid 1 COOH Aspartic acid When ammonia is neutralized with inorganic and organic acids, ammonium salts are formed. This process is carried out in the kidneys. The resulting ammonium salts are excreted in the urine and sweat. Urea synthesis. One of the most effective methods of neutralizing ammonia is a urea synthesis. The urea synthesis scheme was first proposed by the Russian biochemist M. V. Nentsky, who believed that urea is formed from two ammonia molecules and one carbonic acid molecule. In the carbonic acid, the hydroxyl groups are replaced by ammonia with the formation of an intermediate compound of ammonium carboxylic acid. OH 0NH4 nh 2 / / / C-O+2NH3- -♦C = O-2H 2 O- ->C = O \ \ \ OH ONH 4 nh 2 Ammonium carboxylic acid Urea However, this theory did not find further experimental confirmation. Ammonium carboxylic acid in the liver is practically not detected. In addition, this substance is no less toxic than ammonia. 171