In chemistry , pyrophosphates are phosphorus oxyanions that contain two phosphorus atoms in a P−O−P linkage. A number of pyrophosphate salts exist, such as disodium pyrophosphate ( Na 2 H 2 P 2 O 7 ) and tetrasodium pyrophosphate ( Na 4 P 2 O 7 ), among others. Often pyrophosphates are called diphosphates . The parent pyrophosphates are derived from partial or complete neutralization of pyrophosphoric acid . The pyrophosphate bond is also sometimes referred to as a phosphoanhydride bond, a naming convention which emphasizes the loss of water that occurs when two phosphates form a new P−O−P bond, and which mirrors the nomenclature for anhydrides of carboxylic acids . Pyrophosphates are found in ATP and other nucleotide triphosphates, which are important in biochemistry. The term pyrophosphate is also the name of esters formed by the condensation of a phosphorylated biological compound with inorganic phosphate , as for dimethylallyl pyrophosphate . This bond is also referred to as a high-energy phosphate bond.
34-674: (Redirected from E-450 ) E450 or E-450 may refer to: E450 (food additive) E-450, a Ford E-Series van or minibus Olympus E-450 , a camera ThinkPad E450 , laptop E450, a model variant of the Mercedes-Benz E-Class (W213) E-450, an AMD processor with 3D graphics E450 series, a Sony Walkman digital audio player, see Walkman E Series See also [ edit ] [REDACTED] Search for "e450" , "e-450" , "e45-0" , "e4-50" , or "e-4-5-0" on Misplaced Pages. Sun Enterprise 450,
68-580: A Sun Enterprise server computer Canon EOS 450D , a camera 450 (disambiguation) [REDACTED] Topics referred to by the same term This disambiguation page lists articles associated with the same title formed as a letter–number combination. If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=E450&oldid=1213525562 " Category : Letter–number combination disambiguation pages Hidden categories: Short description
102-529: A is comparable to that of acetic acid . Solutions of salts such as BeCl 2 or Al(NO 3 ) 3 in water are noticeably acidic ; the hydrolysis can be suppressed by adding an acid such as nitric acid , making the solution more acidic. Hydrolysis may proceed beyond the first step, often with the formation of polynuclear species via the process of olation . Some "exotic" species such as Sn 3 (OH) 2+ 4 are well characterized. Hydrolysis tends to proceed as pH rises leading, in many cases, to
136-441: A mixture of doubly and singly protonated forms. Disodium pyrophosphate is prepared by thermal condensation of sodium dihydrogen phosphate or by partial deprotonation of pyrophosphoric acid. Pyrophosphates are generally white or colorless. The alkali metal salts are water-soluble. They are good complexing agents for metal ions (such as calcium and many transition metals) and have many uses in industrial chemistry. Pyrophosphate
170-488: A more technical discussion of what occurs during such a hydrolysis, see Brønsted–Lowry acid–base theory . Acid–base-catalysed hydrolyses are very common; one example is the hydrolysis of amides or esters . Their hydrolysis occurs when the nucleophile (a nucleus-seeking agent, e.g., water or hydroxyl ion) attacks the carbon of the carbonyl group of the ester or amide . In an aqueous base, hydroxyl ions are better nucleophiles than polar molecules such as water. In acids,
204-482: A natural inhibitor of hydroxyapatite formation in extracellular fluid (ECF). Cells may channel intracellular PP i into ECF. ANK is a nonenzymatic plasma-membrane PP i channel that supports extracellular PP i levels. Defective function of the membrane PP i channel ANK is associated with low extracellular PP i and elevated intracellular PP i . Ectonucleotide pyrophosphatase/phosphodiesterase (ENPP) may function to raise extracellular PP i . From
238-452: A significant rate in vivo. For example, it is estimated that in each human cell 2,000 to 10,000 DNA purine bases turn over every day due to hydrolytic depurination, and that this is largely counteracted by specific rapid DNA repair processes. Hydrolytic DNA damages that fail to be accurately repaired may contribute to carcinogenesis and ageing . Metal ions are Lewis acids , and in aqueous solution they form metal aquo complexes of
272-423: Is saponification : cleaving esters into carboxylate salts and alcohols . In ester hydrolysis , the hydroxide ion nucleophile attacks the carbonyl carbon. This mechanism is supported by isotope labeling experiments. For example, when ethyl propionate with an oxygen-18 labeled ethoxy group is treated with sodium hydroxide (NaOH), the oxygen-18 is completely absent from the sodium propionate product and
306-457: Is sucrose (table sugar). Hydrolysis of sucrose yields glucose and fructose . Invertase is a sucrase used industrially for the hydrolysis of sucrose to so-called invert sugar . Lactase is essential for digestive hydrolysis of lactose in milk; many adult humans do not produce lactase and cannot digest the lactose in milk. The hydrolysis of polysaccharides to soluble sugars can be recognized as saccharification . Malt made from barley
340-528: Is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution , elimination , and solvation reactions in which water is the nucleophile . Biological hydrolysis is the cleavage of biomolecules where a water molecule is consumed to effect the separation of a larger molecule into component parts. When a carbohydrate is broken into its component sugar molecules by hydrolysis (e.g., sucrose being broken down into glucose and fructose ), this
374-445: Is different from Wikidata All article disambiguation pages All disambiguation pages E450 (food additive) Pyrophosphoric acid is a tetraprotic acid, with four distinct p K a 's: The pKa's occur in two distinct ranges because deprotonations occur on separate phosphate groups. For comparison with the p K a 's for phosphoric acid are 2.14, 7.20, and 12.37. At physiological pH 's, pyrophosphate exists as
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#1732772370663408-519: Is formed, and the fatty acids react with the base, converting them to salts. These salts are called soaps, commonly used in households. In addition, in living systems, most biochemical reactions (including ATP hydrolysis) take place during the catalysis of enzymes . The catalytic action of enzymes allows the hydrolysis of proteins , fats, oils, and carbohydrates . As an example, one may consider proteases (enzymes that aid digestion by causing hydrolysis of peptide bonds in proteins ). They catalyze
442-403: Is needed to place the amide group in the proper position for catalysis. The necessary contacts between an enzyme and its substrates (proteins) are created because the enzyme folds in such a way as to form a crevice into which the substrate fits; the crevice also contains the catalytic groups. Therefore, proteins that do not fit into the crevice will not undergo hydrolysis. This specificity preserves
476-408: Is recognized as saccharification . Hydrolysis reactions can be the reverse of a condensation reaction in which two molecules join into a larger one and eject a water molecule. Thus hydrolysis adds water to break down, whereas condensation builds up by removing water. Usually hydrolysis is a chemical process in which a molecule of water is added to a substance. Sometimes this addition causes both
510-648: Is related to energy metabolism and storage. All living cells require a continual supply of energy for two main purposes: the biosynthesis of micro and macromolecules, and the active transport of ions and molecules across cell membranes. The energy derived from the oxidation of nutrients is not used directly but, by means of a complex and long sequence of reactions, it is channeled into a special energy-storage molecule, adenosine triphosphate (ATP). The ATP molecule contains pyrophosphate linkages (bonds formed when two phosphate units are combined) that release energy when needed. ATP can undergo hydrolysis in two ways: Firstly,
544-413: Is the first member of an entire series of polyphosphates . The anion P 2 O 4− 7 is abbreviated PP i , standing for i norganic p yro p hosphate . It is formed by the hydrolysis of ATP into AMP in cells . For example, when a nucleotide is incorporated into a growing DNA or RNA strand by a polymerase , pyrophosphate (PP i ) is released. Pyrophosphorolysis is the reverse of
578-532: Is used as a source of β-amylase to break down starch into the disaccharide maltose , which can be used by yeast to produce beer . Other amylase enzymes may convert starch to glucose or to oligosaccharides. Cellulose is first hydrolyzed to cellobiose by cellulase and then cellobiose is further hydrolyzed to glucose by beta-glucosidase . Ruminants such as cows are able to hydrolyze cellulose into cellobiose and then glucose because of symbiotic bacteria that produce cellulases. Hydrolysis of DNA occurs at
612-473: The polymerization reaction in which pyrophosphate reacts with the 3′-nucleosidemonophosphate ( NMP or dNMP), which is removed from the oligonucleotide to release the corresponding triphosphate ( dNTP from DNA, or NTP from RNA). The pyrophosphate anion has the structure P 2 O 4− 7 , and is an acid anhydride of phosphate . It is unstable in aqueous solution and hydrolyzes into inorganic phosphate: or in biologists' shorthand notation: In
646-619: The absence of enzymic catalysis, hydrolysis reactions of simple polyphosphates such as pyrophosphate, linear triphosphate, ADP , and ATP normally proceed extremely slowly in all but highly acidic media. (The reverse of this reaction is a method of preparing pyrophosphates by heating phosphates.) This hydrolysis to inorganic phosphate effectively renders the cleavage of ATP to AMP and PP i irreversible , and biochemical reactions coupled to this hydrolysis are irreversible as well. PP i occurs in synovial fluid , blood plasma , and urine at levels sufficient to block calcification and may be
680-415: The carbonyl group becomes protonated, and this leads to a much easier nucleophilic attack. The products for both hydrolyses are compounds with carboxylic acid groups. Perhaps the oldest commercially practiced example of ester hydrolysis is saponification (formation of soap). It is the hydrolysis of a triglyceride (fat) with an aqueous base such as sodium hydroxide (NaOH). During the process, glycerol
714-429: The conversion of cellulose or starch to glucose . Carboxylic acids can be produced from acid hydrolysis of esters. Acids catalyze hydrolysis of nitriles to amides. Acid hydrolysis does not usually refer to the acid catalyzed addition of the elements of water to double or triple bonds by electrophilic addition as may originate from a hydration reaction . Acid hydrolysis is used to prepare monosaccharide with
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#1732772370663748-457: The direction of synthesis when the phosphate bonds have undergone hydrolysis. Monosaccharides can be linked together by glycosidic bonds , which can be cleaved by hydrolysis. Two, three, several or many monosaccharides thus linked form disaccharides , trisaccharides , oligosaccharides , or polysaccharides , respectively. Enzymes that hydrolyze glycosidic bonds are called " glycoside hydrolases " or "glycosidases". The best-known disaccharide
782-468: The general formula M(H 2 O) n . The aqua ions undergo hydrolysis, to a greater or lesser extent. The first hydrolysis step is given generically as Thus the aqua cations behave as acids in terms of Brønsted–Lowry acid–base theory . This effect is easily explained by considering the inductive effect of the positively charged metal ion, which weakens the O−H bond of an attached water molecule, making
816-401: The help of mineral acids but formic acid and trifluoroacetic acid have been used. Acid hydrolysis can be utilized in the pretreatment of cellulosic material, so as to cut the interchain linkages in hemicellulose and cellulose. Alkaline hydrolysis usually refers to types of nucleophilic substitution reactions in which the attacking nucleophile is a hydroxide ion . The best known type
850-442: The hydrogen ion. The hydrolysis of peptides gives amino acids . Many polyamide polymers such as nylon 6,6 hydrolyze in the presence of strong acids. The process leads to depolymerization . For this reason nylon products fail by fracturing when exposed to small amounts of acidic water. Polyesters are also susceptible to similar polymer degradation reactions. The problem is known as environmental stress cracking . Hydrolysis
884-420: The hydrolysis of interior peptide bonds in peptide chains, as opposed to exopeptidases (another class of enzymes, that catalyze the hydrolysis of terminal peptide bonds, liberating one free amino acid at a time). However, proteases do not catalyze the hydrolysis of all kinds of proteins. Their action is stereo-selective: Only proteins with a certain tertiary structure are targeted as some kind of orienting force
918-412: The hydroxide ions whereas the acetate ions combine with hydronium ions to produce acetic acid . In this case the net result is a relative excess of hydroxide ions, yielding a basic solution . Strong acids also undergo hydrolysis. For example, dissolving sulfuric acid ( H 2 SO 4 ) in water is accompanied by hydrolysis to give hydronium and bisulfate , the sulfuric acid's conjugate base . For
952-407: The integrity of other proteins such as hormones , and therefore the biological system continues to function normally. Upon hydrolysis, an amide converts into a carboxylic acid and an amine or ammonia (which in the presence of acid are immediately converted to ammonium salts). One of the two oxygen groups on the carboxylic acid are derived from a water molecule and the amine (or ammonia) gains
986-550: The liberation of a proton relatively easy. The dissociation constant , pK a , for this reaction is more or less linearly related to the charge-to-size ratio of the metal ion. Ions with low charges, such as Na are very weak acids with almost imperceptible hydrolysis. Large divalent ions such as Ca , Zn , Sn and Pb have a pK a of 6 or more and would not normally be classed as acids, but small divalent ions such as Be undergo extensive hydrolysis. Trivalent ions like Al and Fe are weak acids whose pK
1020-573: The precipitation of a hydroxide such as Al(OH) 3 or AlO(OH) . These substances, major constituents of bauxite , are known as laterites and are formed by leaching from rocks of most of the ions other than aluminium and iron and subsequent hydrolysis of the remaining aluminium and iron. Acetals , imines , and enamines can be converted back into ketones by treatment with excess water under acid-catalyzed conditions: RO·OR−H 3 O−O ; NR·H 3 O−O ; RNR−H 3 O−O . Acid catalysis can be applied to hydrolyses. For example, in
1054-564: The precursor to tens of thousands of terpeness and terpenoids . Various diphosphates are used as emulsifiers , stabilisers , acidity regulators , raising agents , sequestrants , and water retention agents in food processing. They are classified in the E number scheme under E450: In particular, various formulations of diphosphates are used to stabilize whipped cream . Hydrolysis Hydrolysis ( / h aɪ ˈ d r ɒ l ɪ s ɪ s / ; from Ancient Greek hydro- 'water' and lysis 'to unbind')
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1088-403: The removal of terminal phosphate to form adenosine diphosphate (ADP) and inorganic phosphate, with the reaction: Secondly, the removal of a terminal diphosphate to yield adenosine monophosphate (AMP) and pyrophosphate . The latter usually undergoes further cleavage into its two constituent phosphates. This results in biosynthesis reactions, which usually occur in chains, that can be driven in
1122-399: The standpoint of high energy phosphate accounting, the hydrolysis of ATP to AMP and PP i requires two high-energy phosphates, as to reconstitute AMP into ATP requires two phosphorylation reactions. The plasma concentration of inorganic pyrophosphate has a reference range of 0.58–3.78 μM (95% prediction interval). Isopentenyl pyrophosphate converts to geranyl pyrophosphate ,
1156-582: The substance and water molecule to split into two parts. In such reactions, one fragment of the target molecule (or parent molecule) gains a hydrogen ion . It breaks a chemical bond in the compound. A common kind of hydrolysis occurs when a salt of a weak acid or weak base (or both) is dissolved in water. Water spontaneously ionizes into hydroxide anions and hydronium cations . The salt also dissociates into its constituent anions and cations. For example, sodium acetate dissociates in water into sodium and acetate ions. Sodium ions react very little with
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