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Nitrite Reductase
Nitrite reductase refers to any of several classes of enzymes that catalyze the reduction of nitrite. There are two classes of NIR's. A multi haem enzyme reduces NO2− to a variety of products. Copper containing enzymes carry out a single electron transfer to produce nitric oxide. Iron based There are several types of iron based enzymes. Cytochrome cd1, or ''Pseudomonas'' cytochrome oxidase contains two c and two d type hemes with two polypeptide chains. Different forms of this reductase catalyze the formation of nitric oxide or nitrous oxide. A version of this compound was originally called oxidoreductase.html"_;"title="errocytochrome_c-551:oxidoreductase">errocytochrome_c-551:oxidoreductase_It_was_initially_considered_an_oxidase.__It_catalyzes_the_reduction_of_NO2−_to_NO.__This_tetraheme_enzyme_has_two_Protein_subunit.html" ;"title="oxidoreductase.html" ;"title="oxidoreductase.html" ;"title="errocytochrome c-551:oxidoreductase">errocytochrome c-551:oxidoreductase">oxi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. Almost all metabolic processes in the cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts are catalytic RNA molecules, called ribozymes. Enzymes' specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the react ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is Earth's most abundant element, and after hydrogen and helium, it is the third-most abundant element in the universe. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula . Diatomic oxygen gas currently constitutes 20.95% of the Earth's atmosphere, though this has changed considerably over long periods of time. Oxygen makes up almost half of the Earth's crust in the form of oxides.Atkins, P.; Jones, L.; Laverman, L. (2016).''Chemical Principles'', 7th edition. Freeman. Many major classes of organic molecules in living organisms contain oxygen atoms, such as proteins, nucleic acids, carbohydrates, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Azurin
Azurin is a small, periplasmic, bacterial blue copper protein found in ''Pseudomonas'', ''Bordetella'', or ''Alcaligenes'' bacteria. Azurin moderates single-electron transfer between enzymes associated with the cytochrome chain by undergoing oxidation-reduction between Cu(I) and Cu(II). Each monomer of an azurin tetramer has a molecular weight of approximately 14kDa, contains a single copper atom, is intensively blue, and has a fluorescence emission band centered at 308 nm. Azurins and pseudoazurins participate in the denitrification processes in bacteria., including the gram-negative bacteria ''Pseudomonas aeruginosa,'' by interacting with cytochrome c551. Azurin from ''P aeruginosa'' is a type I blue copper protein (cupredoxin), while cytochrome c551 (9 kDa) is a haem-containing cytochrome. Azurin possesses a relatively large hydrophobic patch close to the active site, and two residues in this hydrophobic patch, Met-44 and Met-64, are believed to be involved in its interact ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Achromobacter
''Achromobacter'' is a genus of bacteria, included in the family Alcaligenaceae in the order Burkholderiales. The cells are Gram-negative straight rods and are motile by using one to 20 peritrichous flagella. They are strictly aerobic and are found in water (fresh and marine) and soils.Garrity, George M.; Brenner, Don J.; Krieg, Noel R.; Staley, James T. (eds.) (2005). ''Bergey's Manual of Systematic Bacteriology, Volume Two: The Proteobacteria'', Part C: The Alpha-, Beta-, Delta-, and Epsilonproteobacteria. New York: Springer. . They have also been identified as a contaminant in laboratory cell cultures. They have been identified as opportunistic human pathogens in people with certain immunosuppressive conditions such as cystic fibrosis Cystic fibrosis (CF) is a rare genetic disorder that affects mostly the lungs, but also the pancreas, liver, kidneys, and intestine. Long-term issues include difficulty breathing and coughing up mucus as a result of frequent lung infections. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alcaligenes
''Alcaligenes'' is a genus of Gram-negative, aerobic, rod-shaped bacteria. The species are motile with amphitrichous flagella and rarely nonmotile. It is a genus of non-fermenting bacteria (in the family Alcaligenaceae). Additionally, some strains of ''Alcaligenes'' are capable of anaerobic respiration, but they must be in the presence of nitrate or nitrite; otherwise, their metabolism is respiratory and never fermentative; The genus does not use carbohydrates. Strains of ''Alcaligene''s (such as ''A. faecalis'') are found mostly in the intestinal tracts of vertebrates, decaying materials, dairy products, water, and soil; they can be isolated from human respiratory and gastrointestinal tracts and wounds in hospitalized patients with compromised immune systems. They are occasionally the cause of opportunistic infections, including nosocomial sepsis. ''Alcaligenes faecalis'' causes nosocomial sepsis, arising from contaminated hemodialysis or intravenous fluid, in immunocompromi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bordetella
''Bordetella'' () is a genus of small (0.2 – 0.7 µm), gram-negative coccobacilli of the phylum Pseudomonadota. ''Bordetella'' species, with the exception of '' B. petrii'', are obligate aerobes, as well as highly fastidious, or difficult to culture. All species can infect humans. The first three species to be described ('' B. pertussis'', '' B. parapertussis'', '' B. bronchiseptica''); are sometimes referred to as the 'classical species'. Two of these (''B. bronchiseptica'' and ''B. pertussis'') are also motile. ''B. pertussis'' and occasionally ''B. parapertussis'' cause pertussis or whooping cough in humans, and some ''B. parapertussis'' strains can colonise sheep. ''B. bronchiseptica'' rarely infects healthy humans, though disease in immunocompromised patients has been reported. ''B. bronchiseptica'' causes several diseases in other mammals, including kennel cough and atrophic rhinitis in dogs and pigs, respectively. Other members of the genus cause similar diseases in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudomonas
''Pseudomonas'' is a genus of Gram-negative, Gammaproteobacteria, belonging to the family Pseudomonadaceae and containing 191 described species. The members of the genus demonstrate a great deal of metabolic diversity and consequently are able to colonize a wide range of niches. Their ease of culture ''in vitro'' and availability of an increasing number of ''Pseudomonas'' strain genome sequences has made the genus an excellent focus for scientific research; the best studied species include '' P. aeruginosa'' in its role as an opportunistic human pathogen, the plant pathogen '' P. syringae'', the soil bacterium '' P. putida'', and the plant growth-promoting ''P. fluorescens, P. lini, P. migulae'', and ''P. graminis''. Because of their widespread occurrence in water and plant seeds such as dicots, the pseudomonads were observed early in the history of microbiology. The generic name ''Pseudomonas'' created for these organisms was defined in rather vague terms by Walter Migula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroxylamine
Hydroxylamine is an inorganic compound with the formula . The material is a white crystalline, hygroscopic compound.Greenwood and Earnshaw. ''Chemistry of the Elements.'' 2nd Edition. Reed Educational and Professional Publishing Ltd. pp. 431–432. 1997. Hydroxylamine is almost always provided and used as an aqueous solution. It is consumed almost exclusively to produce Nylon-6. It is also an intermediate in biological nitrification. The oxidation of to hydroxylamine is a step in biological nitrification. History Hydroxylamine was first prepared as hydroxylammonium chloride in 1865 by the German chemist Wilhelm Clemens Lossen (1838-1906); he reacted tin and hydrochloric acid in the presence of ethyl nitrate. It was first prepared in pure form in 1891 by the Dutch chemist Lobry de Bruyn and by the French chemist Léon Maurice Crismer (1858-1944). The coordination complex , known as Crismer's salt, releases hydroxylamine upon heating. Production Hydroxylamine or its salts can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protonation
In chemistry, protonation (or hydronation) is the adding of a proton (or hydron, or hydrogen cation), (H+) to an atom, molecule, or ion, forming a conjugate acid. (The complementary process, when a proton is removed from a Brønsted–Lowry acid, is deprotonation.) Some examples include *The protonation of water by sulfuric acid: *:H2SO4 + H2O H3O+ + *The protonation of isobutene in the formation of a carbocation: *:(CH3)2C=CH2 + HBF4 (CH3)3C+ + *The protonation of ammonia in the formation of ammonium chloride from ammonia and hydrogen chloride: *:NH3( g) + HCl( g) → NH4Cl( s) Protonation is a fundamental chemical reaction and is a step in many stoichiometric and catalytic processes. Some ions and molecules can undergo more than one protonation and are labeled polybasic, which is true of many biological macromolecules. Protonation and deprotonation (removal of a proton) occur in most acid–base reactions; they are the core of most acid–base reaction theories. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valence Electrons
In chemistry and physics, a valence electron is an electron in the outer shell associated with an atom, and that can participate in the formation of a chemical bond if the outer shell is not closed. In a single covalent bond, a shared pair forms with both atoms in the bond each contributing one valence electron. The presence of valence electrons can determine the element's chemical properties, such as its valence—whether it may bond with other elements and, if so, how readily and with how many. In this way, a given element's reactivity is highly dependent upon its electronic configuration. For a main-group element, a valence electron can exist only in the outermost electron shell; for a transition metal, a valence electron can also be in an inner shell. An atom with a closed shell of valence electrons (corresponding to a noble gas configuration) tends to be chemically inert. Atoms with one or two valence electrons more than a closed shell are highly reactive due to the re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Histidine
Histidine (symbol His or H) is an essential amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated –NH3+ form under biological conditions), a carboxylic acid group (which is in the deprotonated –COO− form under biological conditions), and an imidazole side chain (which is partially protonated), classifying it as a positively charged amino acid at physiological pH. Initially thought essential only for infants, it has now been shown in longer-term studies to be essential for adults also. It is encoded by the codons CAU and CAC. Histidine was first isolated by Albrecht Kossel and Sven Gustaf Hedin in 1896. It is also a precursor to histamine, a vital inflammatory agent in immune responses. The acyl radical is histidyl. Properties of the imidazole side chain The conjugate acid (protonated form) of the imidazole side chain in histidine has a p''K''a of approximately 6.0. Thus, below a pH of 6, the imidazole ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arginine
Arginine is the amino acid with the formula (H2N)(HN)CN(H)(CH2)3CH(NH2)CO2H. The molecule features a guanidino group appended to a standard amino acid framework. At physiological pH, the carboxylic acid is deprotonated (−CO2−) and both the amino and guanidino groups are protonated, resulting in a cation. Only the -arginine (symbol Arg or R) enantiomer is found naturally. Arg residues are common components of proteins. It is encoded by the codons CGU, CGC, CGA, CGG, AGA, and AGG. The guanidine group in arginine is the precursor for the biosynthesis of nitric oxide. Like all amino acids, it is a white, water-soluble solid. History Arginine was first isolated in 1886 from yellow lupin seedlings by the German chemist Ernst Schulze and his assistant Ernst Steiger. He named it from the Greek ''árgyros'' (ἄργυρος) meaning "silver" due to the silver-white appearance of arginine nitrate crystals. In 1897, Schulze and Ernst Winterstein (1865–1949) determined the structu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
