72,234 articles
Pyridoxamine-5-phosphate deficiency-developmental and epileptic encephalopathy
Pyridoxamine-5-phosphate deficiency-developmental and epileptic encephalopathy (PNPO-DEE), also called PNPO deficiency or pyridoxal phosphate-responsive seizures, is a rare autosomal recessive PNPO-gene disorder causing drug-resistant neonatal seizures that respond to vitamin B6.
Pyridoxine
Pyridoxine, one of the six vitamin B6 vitamers, is the common supplement and medicinal form of vitamin B6, a coenzyme in over 100 enzyme reactions; high doses cause sensory neuropathy, and US and EU upper limits differ sharply.
Pyridoxine 5′-phosphate oxidase
Pyridoxine 5′-phosphate oxidase (PNPO, EC 1.4.3.5, PdxH) is an FMN-dependent homodimeric enzyme oxidizing PNP and PMP to pyridoxal 5′-phosphate; human gene defects cause PLP-responsive neonatal epileptic encephalopathy.
Pyridoxine-dependent epilepsy
Pyridoxine-dependent-developmental and epileptic encephalopathy (PD-DEE), also known as pyridoxine-dependent epilepsy, is a rare autosomal recessive disorder whose seizures respond to vitamin B6, not anti-epileptic drugs.
Pyrifluquinazon
Pyrifluquinazon (CAS 337458-27-2), a pyridine azomethine insecticide, IRAC Group 9B chordotonal organ TRPV channel modulator sold as PQZ; registered in the US since 2013, not EU-approved, JMPR ADI 0-0.005 mg/kg bw.
Pyriftalid
Pyriftalid (CGA 279233), CAS 135186-78-6, is a Syngenta ALS-inhibitor herbicide for grass weeds in rice, used in Japan and South Korea, not EU-approved, with low mammalian but high Daphnia toxicity.
Pyrimethamine
Pyrimethamine, sold as Daraprim, is an antiparasitic medicine developed by Gertrude Elion and George Hitchings in the early 1950s, the standard therapy for toxoplasmosis and, with sulfadoxine, a malaria treatment.
Pyrimethanil
Pyrimethanil (CAS 53112-28-0) is an anilinopyrimidine fungicide, FRAC Group 9, inhibiting methionine biosynthesis in Botrytis and Venturia; EU approval renewed 2026-2041, with post-harvest citrus use and noted bee and fish risks.
Pyrimidifen
Pyrimidifen (CAS 105779-78-0, Miteclean) is a pyrimidinamine METI acaricide and insecticide, IRAC group 21A, inhibiting mitochondrial complex I; used against mites on fruit and vegetables, commercialized 1995, not EU-approved.
Pyrimidine biosynthesis
Pyrimidine biosynthesis (orotate pathway): six-step de novo route from glutamine, bicarbonate, and aspartate to UMP via CAD, DHODH, and UMPS; regulated by feedback inhibition and targeted by drugs such as leflunomide.
Pyrimidine catabolism
Pyrimidine catabolism, also called the reductive pathway of pyrimidine degradation, breaks down uracil to beta-alanine and thymine to beta-aminoisobutyrate via DPD, dihydropyrimidinase, and beta-ureidopropionase, mainly in liver.
Pyrimidine salvage
Pyrimidine salvage recovers pyrimidine nucleosides and bases from DNA/RNA breakdown via kinases (UCK1/2, DCK, TK1/TK2) and phosphorylases (TYMP, UPP), feeding nucleotide monophosphates back into biosynthesis; relevant to cancer, antiviral, and mitochondrial disease therapy.
Pyrimisulfan
Pyrimisulfan (KUH-021, CAS 221205-90-9) is a Kumiai-discovered sulfonanilide ALS-inhibitor herbicide for paddy rice (Best Partner, 50–75 g a.i./ha) and turf (Vexis); not EU-approved.
Pyriofenone
Pyriofenone (IKF-309; Property, PROLIVO) is an aryl phenyl ketone, FRAC Group 50 fungicide by Ishihara Sangyo Kaisha that disrupts fungal actin to control powdery mildew on cereals, grapes, and vegetables.
Pyriproxyfen
Pyriproxyfen (CAS 95737-68-1), a juvenile hormone mimic insect growth regulator developed by Sumitomo, used against crop pests and Aedes mosquito larvae; EU-approved to 2035, WHO drinking-water assessed.
Pyrithiobac sodium
Pyrithiobac sodium (Staple) is a pyrimidinylthiobenzoate ALS-inhibiting herbicide for post-emergence broadleaf weed control in cotton, first US-registered in 1995, with widespread ALS resistance documented in Amaranthus weeds.
Pyritinol
Pyritinol, also known as pyrithioxin or pyridoxine disulfide, is a synthetic nootropic drug synthesized from vitamin B6 in 1961, used in Europe for cognitive disorders and dementia.
Pyrobaculum
Pyrobaculum: genus of rod-shaped hyperthermophilic archaea (Thermoproteaceae, Huber et al. 1988; type species P. islandicum) growing at 90-100°C in solfataras, respiring on oxygen, nitrate, arsenate, selenium species, iron, thiosulfate, and sulfur.
Pyrococcus
Pyrococcus, genus of hyperthermophilic marine archaea (Thermococcales) named by Fiala and Stetter in 1986; grows optimally near 100 degrees C, ferments sugars to hydrogen, and includes P. furiosus, source of Pfu polymerase and SHI hydrogenase.
Pyrococcus abyssi
Pyrococcus abyssi (strain GE5) is a hyperthermophilic anaerobic euryarchaeon from North Fiji Basin vents at 2,000 m, growing optimally at 96°C, with two replicative DNA polymerases (PolB, PolD) and the Isis PCR polymerase.
Pyrococcus furiosus
Pyrococcus furiosus, hyperthermophilic anaerobic archaeon from Vulcano Island, Italy, grows optimally near 100°C; source of Pfu polymerase and oxygen-resilient SHI hydrogenase used in biofuel cells.
Pyrocystis fusiformis
Pyrocystis fusiformis, a large non-motile bioluminescent marine dinoflagellate (Pyrocystaceae, Gonyaulacales), about 370 µm long, photosynthetic and non-toxic, flashing ~500 ms when sheared; widely cultured and used as a UBAT calibration species.
Pyrodictium
Pyrodictium: anaerobic disc-shaped hyperthermophilic archaea (Pyrodictiaceae, Desulfurococcales) from submarine vents, growing optimally at 97–105°C (max 110°C), connected by unique hollow cannulae, reducing sulfur with hydrogen; species include P. occultum and P. delaneyi.
Pyrola
Pyrola (wintergreens) is a genus of about 42 accepted evergreen herbs in Ericaceae, tribe Pyroleae, native to subarctic and temperate Northern Hemisphere to Guatemala and Sumatera; Asian origin, dust-seed mycoheterotrophy, and use as the Chinese medicine Luxiancao distinguish it.
Pyronaridine
Pyronaridine, a benzonaphthyridine antimalarial synthesized in China in 1970, is used with artesunate (Pyramax) as a WHO-recommended ACT for uncomplicated falciparum malaria; transient transaminase rises are its main safety signal.
Pyronemataceae
Pyronemataceae (Corda, 1842), synonyms Humariaceae and Otidiaceae, is the largest family of cup fungi in Pezizales, Ascomycota, with about 75–78 genera and 500–660 species, mostly temperate, saprotrophic or mycorrhizal, and not monophyletic as circumscribed.
Pyrophosphate hydrolysis
Pyrophosphate hydrolysis (PPi + H2O → 2 Pi), catalyzed by inorganic pyrophosphatase (EC 3.6.1.1), removes PPi from biosynthetic reactions, driving synthesis forward; human enzymes PPA1, PPA2, LHPP.
Pyrophosphate-energised proton pump
Pyrophosphate-energised proton pump (H+-PPase, V-PPase, mPPase, EC 7.1.3.1): an integral membrane enzyme coupling pyrophosphate hydrolysis to H+ or Na+ pumping in plants, protists, bacteria, and archaea, unrelated to ATPases.
Pyroptosis
Pyroptosis: lytic, inflammatory programmed cell death executed by gasdermin D pores after caspase-1/4/5/11 activation, releasing IL-1β and DAMPs; distinct from apoptosis and necroptosis, involved in infection defense, inflammation, and cancer.
Pyroquilon
Pyroquilon (pyroquilone, CGA 49104, Coratop) is a systemic pyrroloquinolinone fungicide, a melanin biosynthesis reductase inhibitor (MBI-R, FRAC 16.1) used against rice blast; developed 1973, marketed 1985, not EU-approved.