Nitrogen assimilation is the formation of organic nitrogen compounds like amino acids from inorganic nitrogen compounds present in the environment. Organisms like plants, fungi and certain bacteria that can fix nitrogen gas (N2) depend on the ability to assimilate nitrate or ammonia for their needs. Other organisms, like animals, depend entirely on organic nitrogen from their food.
Glutamate dehydrogenase is an enzyme observed in both prokaryotes and eukaryotic mitochondria. The aforementioned reaction also yields ammonia, which in eukaryotes is canonically processed as a substrate in the urea cycle. Typically, the α-ketoglutarate to glutamate reaction does not occur in mammals, as glutamate dehydrogenase equilibrium favours the production of ammonia and α-ketoglutarate. Glutamate dehydrogenase also has a very low affinity for ammonia, and therefore toxic levels of ammonia would have to be present in the body for the reverse reaction to proceed. However, in brain, the NAD+/NADH ratio in brain mitochondria encourages oxidative deamination. In bacteria, the ammonia is assimilated to amino acids via glutamate and aminotransferases. In plants, the enzyme can work in either direction depending on environment and stress. Transgenic plants expressing microbial GLDHs are improved in tolerance to herbicide, water deficit, and pathogen infections. They are more nutritionally valuable.
Biosynthesis, i.e., chemical synthesis occurring in biological contexts, is a term most often referring to multi-step, enzyme-catalyzed processes where chemical substances absorbed as nutrients serve as enzyme substrates, with conversion by the living organism either into simpler or more complex products. Examples of biosynthetic pathways include those for the production of amino acids, lipid membrane components, and nucleotides, but also for the production of all classes of biological macromolecules, and of acetyl-coenzyme A, adenosine triphosphate, nicotinamide adenine dinucleotide and other key intermediate and transactional molecules needed for metabolism. Thus, in biosynthesis, any of an array of compounds, from simple to complex, are converted into other compounds, and so it includes both the catabolism and anabolism of complex molecules. Biosynthetic processes are often represented via charts of metabolic pathways. A particular biosynthetic pathway may be located within a single cellular organelle, while others involve enzymes that are located across an array of cellular organelles and structures.
In biochemistry, flavin adenine dinucleotide (FAD) is a redox-active coenzyme associated with various proteins, which is involved with several enzymatic reactions in metabolism. A flavoprotein is a protein that contains a flavin group, which may be in the form of FAD or flavin mononucleotide (FMN). Many flavoproteins are known: components of the succinate dehydrogenase complex, α-ketoglutarate dehydrogenase, and a component of the pyruvate dehydrogenase complex.
Glutamine synthetase (GS) is an enzyme that plays an essential role in the metabolism of nitrogen by catalyzing the condensation of glutamate and ammonia to form glutamine:
Guanosine monophosphate synthetase, also known as GMPS is an enzyme that converts xanthosine monophosphate to guanosine monophosphate.
In enzymology, a GDP-L-fucose synthase (EC 1.1.1.271) is an enzyme that catalyzes the chemical reaction
In enzymology, a glutamate-5-semialdehyde dehydrogenase (EC 1.2.1.41) is an enzyme that catalyzes the chemical reaction
In enzymology, a N-acetyl-gamma-glutamyl-phosphate reductase (EC 1.2.1.38) is an enzyme that catalyzes the chemical reaction
In enzymology, a ferredoxin-NADP+ reductase (EC 1.18.1.2) abbreviated FNR, is an enzyme that catalyzes the chemical reaction
In enzymology, a D-nopaline dehydrogenase (EC 1.5.1.19) is an enzyme that catalyzes the chemical reaction
In enzymology, a ferredoxin—nitrite reductase (EC 1.7.7.1) is an enzyme that catalyzes the chemical reaction
In enzymology, a glutamate synthase (ferredoxin) (EC 1.4.7.1) is an enzyme that catalyzes the chemical reaction
In enzymology, a glutamate synthase (NADH) (EC 1.4.1.14) is an enzyme that catalyzes the chemical reaction
In enzymology, a saccharopine dehydrogenase (NADP+, L-lysine-forming) (EC 1.5.1.8) is an enzyme that catalyzes the chemical reaction
In enzymology, a 4-methyleneglutamate—ammonia ligase (EC 6.3.1.7) is an enzyme that catalyzes the chemical reaction
In enzymology, a phosphoribosylformylglycinamidine synthase (EC 6.3.5.3) is an enzyme that catalyzes the chemical reaction
In enzymology, 4-aminobutyrate transaminase, also called GABA transaminase or 4-aminobutyrate aminotransferase, or GABA-T, is an enzyme that catalyzes the chemical reaction:
Glutamate synthase is an enzyme and frequently abbreviated as GOGAT. This enzyme manufactures glutamate from glutamine and α-ketoglutarate, and thus along with glutamine synthetase plays a central role in the regulation of nitrogen assimilation in photosynthetic eukaryotes and prokaryotes. This is of great importance as primary productivity in many marine environments is regulated by the availability of inorganic nitrogen.
In enzymology, a prostaglandin-F synthase (PGFS; EC 1.1.1.188) is an enzyme that catalyzes the chemical reaction:
