All articles starting with P
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Pyrrhotite
Pyrrhotite is a non-stoichiometric iron sulfide mineral, Fe₁₋ₓS, whose iron vacancies make it magnetic; it is abundant in the crust and common in nickel and copper ores.
Pyrrhura
Pyrrhura (Bonaparte, 1856) is a genus of small Neotropical parakeets, called conures in aviculture, spanning Amazonian, Atlantic, Andean, and Central American forests; mtDNA work split the picta-leucotis complex, with species from Least Concern to Critically Endangered.
Pyrrhus of Epirus
Pyrrhus (Πύρρος, 319/318–272 BCE), Molossian king of Epirus and briefly Macedonia, famed for his costly victories over Rome at Heraclea and Asculum, the origin of "Pyrrhic victory," and Hannibal's ranking of him second only to Alexander.
Pyrrhus's campaign in Sicily
Pyrrhus's campaign in Sicily, also called the Pyrrhic War in Sicily, was Pyrrhus of Epirus's 278–276 BC expedition against Carthage, invited by Sicily's Greek cities.
Pyrrichos
Pyrrichos (Πύρριχος), ancient Laconian polis in the Mani peninsula, Peloponnese; member of the Eleutherolakonian League per Pausanias, identified with modern Kavalos/Pyrrhichos, Archaic-to-Roman settlement near Vachos, East Mani.
Pyrrole
Pyrrole is a colorless, aromatic five-membered heterocycle with formula C₄H₅N, detected in coal tar in 1834 and parent of the ring in heme, chlorophyll, and cobalamin.
Pyrrole-, furan- and thiophene-carboxylic acids
Pyrrole-, furan- and thiophene-carboxylic acids are carboxylic acids on five-membered heteroaromatic rings, ranging in acidity from pKa 3.15 to 5.0; furan acids are made from biomass and FDCA is a monomer of the polyester PEF.
Pyrrolidine
Pyrrolidine, also known as tetrahydropyrrole or azacyclopentane, is a colorless, strongly basic five-membered cyclic secondary amine (C₄H₉N) used industrially and found in drugs and tobacco.
Pyrrolizidine and quinolizidine alkaloid biosynthesis
Pyrrolizidine and quinolizidine alkaloid biosynthesis covers two plant pathways from amino-acid-derived diamines: putrescine leads to retronecine and senecionine N-oxide, while cadaverine yields lupin alkaloids such as lupinine and sparteine.
Pyrroloquinoline quinone
Pyrroloquinoline quinone (PQQ, methoxatin) is a peptide-derived tricyclic ortho-quinone redox cofactor of bacterial dehydrogenases, biosynthesized from PqqA, found in foods, and sold as a supplement.
Pyrrolysine
Pyrrolysine (Pyl) is the 22nd genetically encoded amino acid, a lysine derivative encoded by the UAG amber codon in certain methanogenic archaea and a few bacteria.
Pyrrolysine-based genetic code expansion
Pyrrolysine-based genetic code expansion engineers the natural pyrrolysine machinery of methanogenic archaea to site-specifically insert hundreds of noncanonical amino acids into proteins in living cells.
Pyrros Dimas
Pyrros Dimas (Πύρρος Δήμας, born 1971, Himarë, Albania; earlier Pirro Dhima), Greek weightlifter, triple Olympic champion 1992, 1996, 2000 and Athens 2004 bronze medalist; later IWF official and USA Weightlifting technical director.
Pyrus
Pyrus is the pear genus of Rosaceae, native to temperate Eurasia and NW Africa, with about 77 accepted species, Occidental and Oriental clades, and independently domesticated European and Asian pears.
Pyrus calleryana
Pyrus calleryana, Callery or Bradford pear, is an Asian Rosaceae tree native to China, Korea, Japan, Taiwan, and Vietnam, planted ornamentally in the US since the early 1900s and now invasive there because cultivar cross-pollination yields viable, bird-dispersed seed.
Pyrus communis
Pyrus communis, the European pear, is a Rosaceae tree native from Europe to northern Iraq, domesticated separately in Europe and the Caucasus, fifth most produced fruit worldwide, with cultivars like Bartlett and Bosc.
Pyrus pyrifolia
Pyrus pyrifolia (Burm.f.) Nakai, the Asian or nashi pear (syn. Pyrus serotina), is a Rosaceae pear tree native to southern China and Indochina, cultivated over 3,000 years; round crisp high-sugar fruit ripened on the tree, leading cultivars Chojuro, Nijisseiki, Kosui, Hosui.
Pyruvate carboxylase
Pyruvate carboxylase (PC, EC 6.4.1.1), pyruvic carboxylase, is a biotin-dependent mitochondrial tetrameric enzyme converting pyruvate to oxaloacetate for gluconeogenesis, lipogenesis, and insulin secretion; PC gene mutations cause autosomal recessive pyruvate carboxylase deficiency.
Pyruvate carboxylase deficiency
Pyruvate carboxylase deficiency (PC deficiency), a rare autosomal recessive disorder of the PC gene at 11q13.4-q13.5, causing lactic acidosis; types A, B, and C differ in severity.
Pyruvate dehydrogenase
Pyruvate dehydrogenase (PDC/PDH): mitochondrial multienzyme complex converting pyruvate to acetyl-CoA, CO2, NADH via E1, E2, E3 with five cofactors; regulated by PDK/PDP phosphorylation; deficiency causes lactic acidosis.
Pyruvate dehydrogenase complex
Pyruvate dehydrogenase complex (PDC, PDHc): mitochondrial multi-enzyme assembly (E1, E2, E3, 5-12 MDa) converting pyruvate to acetyl-CoA, CO2, and NADH; regulated by PDK/PDP phosphorylation; deficient in PDC deficiency and dysregulated in cancer.
Pyruvate dehydrogenase deficiency
Pyruvate dehydrogenase deficiency (PDHD, PDCD) is a genetic mitochondrial disorder impairing conversion of pyruvate to acetyl-CoA, causing congenital lactic acidosis and neurological degeneration; mostly X-linked PDHA1, treated with ketogenic diet and dichloroacetate.
Pyruvate dehydrogenase E1 component
Pyruvate dehydrogenase E1 (EC 1.2.4.1), the ThDP-dependent first enzyme of the PDH complex, decarboxylates pyruvate and acetylates E2 lipoyl groups; mammalian E1 is an alpha2beta2 tetramer regulated by PDK/PDP phosphorylation of E1alpha.
Pyruvate formate-lyase 1 activating enzyme
Pyruvate formate-lyase 1 activating enzyme (PFL-AE), a radical SAM enzyme of E. coli, uses a [4Fe-4S] cluster and SAM to install the Gly734 glycyl radical on pyruvate formate-lyase via an organometallic Ω intermediate.
Pyruvate kinase
Pyruvate kinase is the glycolytic enzyme catalyzing the irreversible final step of glycolysis, converting phosphoenolpyruvate and ADP to pyruvate and ATP; its deficiency causes chronic hemolytic anemia.
Pyruvate kinase deficiency
Pyruvate kinase deficiency (PKD, CNSHA2) is an autosomal recessive PKLR-gene glycolytic enzyme defect causing chronic hemolytic anemia, gallstones, and iron overload; treated with transfusions, splenectomy, and the FDA-approved activator mitapivat (Pyrukynd, 2022).
Pyruvate metabolism
Pyruvate metabolism, also called the Cori cycle pathway (Reactome R-HSA-70268), covers production of pyruvate by glycolysis and its fates: acetyl-CoA via PDH, oxaloacetate via pyruvate carboxylase, lactate via LDH, and related human diseases.
Pyruvate oxidase
Pyruvate oxidase (EC 1.2.3.3, spxB in streptococci) is a bacterial FAD- and thiamine diphosphate-dependent flavoprotein that oxidatively decarboxylates pyruvate with phosphate and oxygen to acetyl phosphate, CO2, and H2O2, distinct from the E. coli acetate-forming EC 1.2.2.2 variant.
Pyruvate, phosphate dikinase
Pyruvate, phosphate dikinase (PPDK, EC 2.7.9.1) reversibly interconverts PEP and pyruvate using ATP, PPi, and AMP; it regenerates PEP in C4 photosynthesis, supports gluconeogenesis, and serves anaerobic glycolysis in bacteria and protists.
Pyruvic acid
Pyruvic acid, also called acetylformic acid, is the simplest alpha-keto carboxylic acid; at neutral pH it is pyruvate, the junction of glycolysis and the citric acid cycle.