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ammonia assimilation cycle I

The primary nitrogen assimilation routes in photosynthetic eukaryotes and prokaryotes are nitrogen fixation, nitrate assimilation, and ammonia assimilation. Ammonia is liberated by photorespiration, protein and amino acid metabolism, and the breakdown of nitrogen transport compounds. The rate of ammonia generation during photorespiration is about 10 times the rate of nitrate assimilation. The ammonia released from photorespiration is immediately re-assimilated via the ammonia assimilation cycle. The net result of this cycle is the conversion of one molecule of ammonia to one molecule of glutamate at the expense of one ATP molecule. The pathway includes two steps catalyzed by : CPLX-4585 "glutamine synthetase" (GS) and : MONOMER-7421 "glutamate synthase" (also known as glutamine oxoglutarate aminotansferase or GOGAT), and thus is often referred to as the GS/GOGAT pathway. Two types of GOGAT are known in photosynthetic organisms - NADH-dependent, and ferredoxin-dependent. NADH-GOGAT is found in the nucleus of vascular plants, fungi, and diatoms. The ferredoxin-dependent enzyme is only found in Cyanobacteria and photosynthetic eukaryotes (see : PWY-6964). An NADPH-dependent version of GOGAT is found in non-photosynthetic bacteria and archaea (see : AMMASSIM-PWY).

from BIOCYC source record: ARA_PWY-6963
Type: pathway
Taxonomic scope
organism-specific biosystem

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