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Phosphoribosyl pyrophosphate (PRPP) is a pentose phosphate. It is a biochemical intermediate in the formation of purine nucleotides via inosine-5-monophosphate, as well as in pyrimidine nucleotide formation. Hence it is a building block for DNA and RNA.
The enzyme phosphoribosyl pyrophosphate synthetase (PRS) catalyzes the formation of phosphoribosyl pyrophosphate which is a substrate for synthesis of purine and pyrimidine nucleotides, histidine, tryptophan and NAD. PRS exists as a complex with two catalytic subunits and two associated subunits.
A key regulatory step is the production of 5-phospho-α-D-ribosyl 1-pyrophosphate by ribose-phosphate diphosphokinase, which is activated by inorganic phosphate and inactivated by purine ribonucleotides. It is not the committed step to purine synthesis because PRPP is also used in pyrimidine synthesis and salvage pathways.
Activation of ribose 5-phosphate to phosphoribosyl pyrophosphate by ribose-phosphate diphosphokinase. PRPP also plays an important role in pyrimidine ribonucleotide synthesis. During the fifth step of pyrimidine nucleotide synthesis, PRPP covalently links to orotate at the one-position carbon on the ribose unit.
PyMol rendering of phosphoribosyl pyrophosphate synthetase I (human) as a homodimer, formed by two subunits (red and blue). Three homodimers form the active enzyme complex. Crystallization and X-ray diffraction studies elucidated the structure of the enzyme, which was isolated by cloning, protein expression, and purification techniques.
A closeup of the skin on an Eldon's galaxias. The slime coat (also fish slime, mucus layer or slime layer) is the coating of mucus covering the body of all fish.An important part of fish anatomy, it serves many functions, depending on species, ranging from locomotion, care and feeding of offspring, to resistance against diseases and parasites.
Amidophosphoribosyltransferase (ATase), also known as glutamine phosphoribosylpyrophosphate amidotransferase (GPAT), is an enzyme responsible for catalyzing the conversion of 5-phosphoribosyl-1-pyrophosphate (PRPP) into 5-phosphoribosyl-1-amine (PRA), using the amine group from a glutamine side-chain.
Fish from multiple groups can live out of the water for extended time periods. Amphibious fish such as the mudskipper can live and move about on land for up to several days, or live in stagnant or otherwise oxygen depleted water. Many such fish can breathe air via a variety of mechanisms. The skin of anguillid eels may absorb