Adenosine diphosphate (ADP), also known as adenosine pyrophosphate (APP), is an important organic compound in metabolism and is essential to the flow of energy in living cells. ADP consists of three important structural components: a sugar backbone attached to adenine and two phosphate groups bonded to the 5 carbon atom of ribose. The diphosphate group of ADP is attached to the 5’ carbon of the sugar backbone, while the adenine attaches to the 1’ carbon.
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.
In enzymology, an aspartate—ammonia ligase (ADP-forming) (EC 6.3.1.4) is an enzyme that catalyzes the chemical reaction
In enzymology, an adenosine-phosphate deaminase (EC 3.5.4.17) is an enzyme that catalyzes the chemical reaction
In enzymology, a 5-methyldeoxycytidine-5'-phosphate kinase is an enzyme that catalyzes the chemical reaction
In enzymology, an adenylylsulfate-ammonia adenylyltransferase (EC 2.7.7.51) is an enzyme that catalyzes the chemical reaction adenylyl sulfate + NH3 adenosine 5'-phosphoramidate + sulfate.
In enzymology, an ADP—thymidine kinase is an enzyme that catalyzes the chemical reaction
In enzymology, arginine kinase is an enzyme that catalyzes the chemical reaction
In enzymology, a carbamate kinase (EC 2.7.2.2) is an enzyme that catalyzes the chemical reaction
In enzymology, a (deoxy)nucleoside-phosphate kinase is an enzyme that catalyzes the chemical reaction
In enzymology, a diphosphoinositol-pentakisphosphate kinase is an enzyme that catalyzes the chemical reaction
In enzymology, a farnesyl-diphosphate kinase is an enzyme that catalyzes the chemical reaction
In enzymology, a glucose-1-phosphate adenylyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a [glutamate—ammonia-ligase] adenylyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a nucleoside-triphosphate-adenylate kinase is an enzyme that catalyzes the chemical reaction
In enzymology, a phosphomethylpyrimidine kinase is an enzyme that catalyzes the chemical reaction
In enzymology, a phosphoramidate-hexose phosphotransferase (EC 2.7.1.62) is an enzyme that catalyzes the chemical reaction
In enzymology, a ribose 1,5-bisphosphate phosphokinase is an enzyme that catalyzes the chemical reaction
In enzymology, a thiamine-diphosphate kinase is an enzyme involved in thiamine metabolism. It catalyzes the chemical reaction
The Purine Nucleotide Cycle is a metabolic pathway in protein metabolism requiring the amino acids aspartate and glutamate. The cycle is used to regulate the levels of adenine nucleotides, in which ammonia and fumarate are generated. AMP coverts into IMP and the byproduct ammonia. IMP converts to S-AMP (adenylosuccinate), which then coverts to AMP and the byproduct fumarate. The fumarate goes on to produce ATP (energy) via oxidative phosphorylation as it enters the Krebs cycle and then the electron transport chain. Lowenstein first described this pathway and outlined its importance in processes including amino acid catabolism and regulation of flux through glycolysis and the Krebs cycle.
