Ethylenediaminetetraacetic acid

Last updated
Ethylenediaminetetraacetic acid
EDTA.svg
Names
IUPAC name
N,N′-(Ethane-1,2-diyl)bis[N-(carboxymethyl)glycine] [1]
Systematic IUPAC name
2,2′,2′′,2′′′-(Ethane-1,2-diyldinitrilo)tetraacetic acid [1]
Other names
  • EthyleneDiamineTetraAcetic acid
  • Diaminoethane-tetraacetic acid
  • Edetic acid (conjugate base edetate) (INN, USAN)
  • Versene
Identifiers
3D model (JSmol)
AbbreviationsEDTA, H4EDTA
1716295
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.000.409 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 200-449-4
144943
KEGG
MeSH Edetic+Acid
PubChem CID
RTECS number
  • AH4025000
UNII
UN number 3077
  • InChI=1S/C10H16N2O8/c13-7(14)3-11(4-8(15)16)1-2-12(5-9(17)18)6-10(19)20/h1-6H2,(H,13,14)(H,15,16)(H,17,18)(H,19,20) Yes check.svgY
    Key: KCXVZYZYPLLWCC-UHFFFAOYSA-N Yes check.svgY
  • OC(=O)CN(CCN(CC(O)=O)CC(O)=O)CC(O)=O
Properties
C10H16N2O8
Molar mass 292.244 g·mol−1
AppearanceColourless crystals
Density 0.860 g cm−3 (at 20 °C)
log P −0.836
Acidity (pKa)2.0, 2.7, 6.16, 10.26 [2]
Thermochemistry
−1765.4 to −1758.0 kJ mol−1
−4461.7 to −4454.5 kJ mol−1
Pharmacology
S01XA05 ( WHO ) V03AB03 ( WHO ) (salt)
  • Intramuscular
  • Intravenous
Hazards
GHS labelling:
GHS-pictogram-exclam.svg
Warning
H319
P305+P351+P338
NFPA 704 (fire diamond)
NFPA 704.svgHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
0
0
Lethal dose or concentration (LD, LC):
1000 mg/kg (oral, rat) [3]
Related compounds
Related alkanoic acids
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Ethylenediaminetetraacetic acid (EDTA), also called EDTA acid after its own abbreviation, is an aminopolycarboxylic acid with the formula [CH2N(CH2CO2H)2]2. This white, water-insoluble solid is widely used to bind to iron (Fe2+/Fe3+) and calcium ions (Ca2+), forming water-soluble complexes even at neutral pH. It is thus used to dissolve Fe- and Ca-containing scale as well as to deliver iron ions under conditions where its oxides are insoluble. EDTA is available as several salts, notably disodium EDTA, sodium calcium edetate, and tetrasodium EDTA, but these all function similarly. [4]

Contents

Uses

Textiles and paper

In industry, EDTA is mainly used to sequester (bind or confine) metal ions in aqueous solution. In the textile industry, it prevents metal ion impurities from modifying colours of dyed products. In the pulp and paper industry, EDTA inhibits the ability of metal ions, especially Mn2+, from catalysing the disproportionation of hydrogen peroxide, which is used in chlorine-free bleaching.

Food

In a similar manner, EDTA is added to some food as a preservative or stabiliser to prevent catalytic oxidative decolouration, which is catalysed by metal ions. [5]

Water softener

The reduction of water hardness in laundry applications and the dissolution of scale in boilers both rely on EDTA and related complexants to bind Ca2+, Mg2+, as well as other metal ions. Once bound to EDTA, these metal complexes are less likely to form precipitates or to interfere with the action of the soaps and detergents.[ citation needed ] For similar reasons, cleaning solutions often contain EDTA. In a similar manner EDTA is used in the cement industry for the determination of free lime and free magnesia in cement and clinkers. [6] [ page needed ]

The solubilisation of Fe3+ ions at or below near neutral pH can be accomplished using EDTA. This property is useful in agriculture including hydroponics. However, given the pH dependence of ligand formation, EDTA is not helpful for improving iron solubility in above neutral soils. [7] Otherwise, at near-neutral pH and above, iron(III) forms insoluble salts, which are less bioavailable to susceptible plant species.

Scrubbing

Aqueous [Fe(EDTA)]− is used for removing ("scrubbing") hydrogen sulfide from gas streams. This conversion is achieved by oxidising the hydrogen sulfide to elemental sulfur, which is non-volatile:

2 [Fe(EDTA)]− + H2S → 2 [Fe(EDTA)]2− + S + 2 H+

In this application, the iron(III) centre is reduced to its iron(II) derivative, which can then be reoxidised by air. In similar manner, nitrogen oxides are removed from gas streams using [Fe(EDTA)]2−.

The oxidising properties of [Fe(EDTA)]− are also exploited in photography, where it is used to solubilise silver particles. [4]

Ion-exchange chromatography

EDTA was used in separation of the lanthanide metals by ion-exchange chromatography. Perfected by F. H. Spedding et al. in 1954, the method relies on the steady increase in stability constant of the lanthanide EDTA complexes with atomic number. [8] Using sulfonated polystyrene beads and Cu2+ as a retaining ion, EDTA causes the lanthanides to migrate down the column of resin while separating into bands of pure lanthanides. The lanthanides elute in order of decreasing atomic number. Due to the expense of this method, relative to countercurrent solvent extraction, ion exchange is now used only to obtain the highest purities of lanthanides (typically greater than 99.99%).[ citation needed ]

Medicine

Sodium calcium edetate, an EDTA derivative, is used to bind metal ions in the practice of chelation therapy, such as for treating mercury and lead poisoning. [9] It is used in a similar manner to remove excess iron from the body. This therapy is used to treat the complication of repeated blood transfusions, as would be applied to treat thalassaemia.

Dentistry

Dentists and endodontists use EDTA solutions to remove inorganic debris (smear layer) and lubricate the root canals in endodontics. This procedure helps prepare root canals for obturation. Furthermore, EDTA solutions with the addition of a surfactant loosen up calcifications inside a root canal and allow instrumentation (canal shaping) and facilitate apical advancement of a file in a tight or calcified root canal towards the apex.

Eyedrops

It serves as a preservative (usually to enhance the action of another preservative such as benzalkonium chloride or thiomersal) in ocular preparations and eyedrops.

Analysis

In medical diagnosis and organ function tests (here, kidney function test), the chromium(III) complex [Cr(EDTA)]− (as radioactive chromium-51 (51Cr)) is administered intravenously and its filtration into the urine is monitored. This method is useful for evaluating glomerular filtration rate (GFR) in nuclear medicine. [10]

EDTA is used extensively in the analysis of blood. It is an anticoagulant for blood samples for CBC/FBCs, where the EDTA chelates the calcium present in the blood specimen, arresting the coagulation process and preserving blood cell morphology. [11] Tubes containing EDTA are marked with lavender (purple) or pink tops. [12] EDTA is also in tan top tubes for lead testing and can be used in royal blue top tubes for trace metal testing. [12]

EDTA is a slime dispersant, and has been found to be highly effective in reducing bacterial growth during implantation of intraocular lenses (IOLs). [13]

Alternative medicine

Some alternative practitioners believe EDTA acts as an antioxidant, preventing free radicals from injuring blood vessel walls, therefore reducing atherosclerosis. [14] These ideas are unsupported by scientific studies, and seem to contradict some currently accepted principles. [15] The U.S. FDA has not approved it for the treatment of atherosclerosis. [16]

Cosmetics

In shampoos, cleaners, and other personal care products, EDTA salts are used as a sequestering agent to improve their stability in air. [17]

Laboratory applications

In the laboratory, EDTA is widely used for scavenging metal ions: In biochemistry and molecular biology, ion depletion is commonly used to deactivate metal-dependent enzymes, either as an assay for their reactivity or to suppress damage to DNA, proteins, and polysaccharides. [18] EDTA also acts as a selective inhibitor against dNTP hydrolyzing enzymes (Taq polymerase, dUTPase, MutT), [19] liver arginase [20] and horseradish peroxidase [21] independently of metal ion chelation. These findings urge the rethinking of the utilisation of EDTA as a biochemically inactive metal ion scavenger in enzymatic experiments. In analytical chemistry, EDTA is used in complexometric titrations and analysis of water hardness or as a masking agent to sequester metal ions that would interfere with the analyses.

EDTA finds many specialised uses in the biomedical labs, such as in veterinary ophthalmology as an anticollagenase to prevent the worsening of corneal ulcers in animals. In tissue culture, EDTA is used as a chelating agent that binds to calcium and prevents joining of cadherins between cells, preventing clumping of cells grown in liquid suspension, or detaching adherent cells for passaging. In histopathology, EDTA can be used as a decalcifying agent making it possible to cut sections using a microtome once the tissue sample is demineralised.

EDTA is also known to inhibit a range of metallopeptidases, the method of inhibition occurs via the chelation of the metal ion required for catalytic activity. [22] EDTA can also be used to test for bioavailability of heavy metals in sediments. However, it may influence the bioavailability of metals in solution, which may pose concerns regarding its effects in the environment, especially given its widespread uses and applications.

EDTA is also used to remove crud (corroded metals) from fuel rods in nuclear reactors. [23]

Side effects

EDTA exhibits low acute toxicity with LD50 (rat) of 2.0 g/kg to 2.2 g/kg. [4] It has been found to be both cytotoxic and weakly genotoxic in laboratory animals. Oral exposures have been noted to cause reproductive and developmental effects. [17] The same study [17] also found that both dermal exposure to EDTA in most cosmetic formulations and inhalation exposure to EDTA in aerosolised cosmetic formulations would produce exposure levels below those seen to be toxic in oral dosing studies.

Synthesis

The compound was first described in 1935 by Ferdinand Münz, [24] who prepared the compound from ethylenediamine and chloroacetic acid. [25] Today, EDTA is mainly synthesised from ethylenediamine (1,2-diaminoethane), formaldehyde, and sodium cyanide. [26] This route yields the tetrasodium EDTA, which is converted in a subsequent step into the acid forms:

H2NCH2CH2NH2 + 4  CH2O + 4  NaCN + 4 H2O → (NaO2CCH2)2NCH2CH2N(CH2CO2Na)2 + 4  NH3
(NaO2CCH2)2NCH2CH2N(CH2CO2Na)2 + 4  HCl → (HO2CCH2)2NCH2CH2N(CH2CO2H)2 + 4  NaCl

This process is used to produce about 80,000 tonnes of EDTA each year. Impurities cogenerated by this route include glycine and nitrilotriacetic acid; they arise from reactions of the ammonia coproduct. [4]

Nomenclature

To describe EDTA and its various protonated forms, chemists distinguish between EDTA4−, the conjugate base that is the ligand, and H4EDTA, the precursor to that ligand. At very low pH (very acidic conditions) the fully protonated H6EDTA2+ form predominates, whereas at very high pH or very basic condition, the fully deprotonated EDTA4− form is prevalent. In this article, the term EDTA is used to mean H4−xEDTAx−, whereas in its complexes EDTA4− stands for the tetraanion ligand.

Coordination chemistry principles

Metal-EDTA chelate as found in Co(III) complexes Metal-EDTA.svg
Metal–EDTA chelate as found in Co(III) complexes
Structure of [Fe(EDTA)(H2O)] , showing that the EDTA ligand does not fully encapsulate Fe(III), which is seven-coordinate SFEDTD01.png
Structure of [Fe(EDTA)(H2O)] , showing that the EDTA ligand does not fully encapsulate Fe(III), which is seven-coordinate

In coordination chemistry, EDTA4− is a member of the aminopolycarboxylic acid family of ligands. EDTA4− usually binds to a metal cation through its two amines and four carboxylates, i.e., it is a hexadentate ("six-toothed") chelating agent. Many of the resulting coordination compounds adopt octahedral geometry. Although of little consequence for its applications, these octahedral complexes are chiral. The cobalt(III) anion [Co(EDTA)]− has been resolved into enantiomers. [28] Many complexes of EDTA4− adopt more complex structures due to either the formation of an additional bond to water, i.e. seven-coordinate complexes, or the displacement of one carboxylate arm by water. The iron(III) complex of EDTA is seven-coordinate. [29] Early work on the development of EDTA was undertaken by Gerold Schwarzenbach in the 1940s. [30] EDTA forms especially strong complexes with Mn(II), Cu(II), Fe(III), Pb(II) and Co(III). [31] [ page needed ]

Several features of EDTA's complexes are relevant to its applications. First, because of its high denticity, this ligand has a high affinity for metal cations:

[Fe(H2O)6]3+ + H4EDTA ⇌ [Fe(EDTA)]− + 6 H2O + 4 H+  Keq = 1025.1

Written in this way, the equilibrium quotient shows that metal ions compete with protons for binding to EDTA. Because metal ions are extensively enveloped by EDTA, their catalytic properties are often suppressed. Finally, since complexes of EDTA4− are anionic, they tend to be highly soluble in water. For this reason, EDTA is able to dissolve deposits of metal oxides and carbonates.

The pKa values of free EDTA are 0, 1.5, 2, 2.66 (deprotonation of the four carboxyl groups) and 6.16, 10.24 (deprotonation of the two amino groups). [32]

Environmental concerns

Abiotic degradation

EDTA is in such widespread use that questions have been raised whether it is a persistent organic pollutant. While EDTA serves many positive functions in different industrial, pharmaceutical and other avenues, the longevity of EDTA can pose serious issues in the environment. The degradation of EDTA is slow. It mainly occurs abiotically in the presence of sunlight. [33]

The most important process for the elimination of EDTA from surface waters is direct photolysis at wavelengths below 400 nm. [34] Depending on the light conditions, the photolysis half-lives of iron(III) EDTA in surface waters can range as low as 11.3 minutes up to more than 100 hours. [35] Degradation of FeEDTA, but not EDTA itself, produces iron complexes of the triacetate (ED3A), diacetate (EDDA), and monoacetate (EDMA) – 92% of EDDA and EDMA biodegrades in 20 hours while ED3A displays significantly higher resistance. Many environmentally-abundant EDTA species (such as Mg2+ and Ca2+) are more persistent.

Biodegradation

In many industrial wastewater treatment plants, EDTA elimination can be achieved at about 80% using microorganisms. [36] Resulting byproducts are ED3A and iminodiacetic acid (IDA) – suggesting that both the backbone and acetyl groups were attacked. Some microorganisms have even been discovered to form nitrates out of EDTA, but they function optimally at moderately alkaline conditions of pH 9.0–9.5. [37]

Several bacterial strains isolated from sewage treatment plants efficiently degrade EDTA. Specific strains include Agrobacterium radiobacter ATCC 55002 [38] and the sub-branches of Pseudomonadota like BNC1, BNC2, [39] and strain DSM 9103. [40] The three strains share similar properties of aerobic respiration and are classified as gram-negative bacteria. Unlike photolysis, the chelated species is not exclusive to iron(III) in order to be degraded. Rather, each strain uniquely consumes varying metal–EDTA complexes through several enzymatic pathways. Agrobacterium radiobacter only degrades Fe(III) EDTA [39] while BNC1 and DSM 9103 are not capable of degrading iron(III) EDTA and are more suited for calcium, barium, magnesium and manganese(II) complexes. [41] EDTA complexes require dissociation before degradation.

Alternatives to EDTA

Interest in environmental safety has raised concerns about biodegradability of aminopolycarboxylates such as EDTA. These concerns incentivize the investigation of alternative aminopolycarboxylates. [33] Candidate chelating agents include nitrilotriacetic acid (NTA), iminodisuccinic acid (IDS), polyaspartic acid, S,S-ethylenediamine-N,N′-disuccinic acid (EDDS), methylglycinediacetic acid (MGDA), and L-Glutamic acid N,N-diacetic acid, tetrasodium salt (GLDA). [42]

Iminodisuccinic acid (IDS)

Commercially used since 1998, iminodisuccinic acid (IDS) biodegrades by about 80% after only 7 days. IDS binds to calcium exceptionally well and forms stable compounds with other heavy metal ions. In addition to having a lower toxicity after chelation, IDS is degraded by Agrobacterium tumefaciens (BY6), which can be harvested on a large scale. The enzymes involved, IDS epimerase and C−N lyase, do not require any cofactors. [43]

Polyaspartic acid

Polyaspartic acid, like IDS, binds to calcium and other heavy metal ions. It has many practical applications including corrosion inhibitors, wastewater additives, and agricultural polymers. A Polyaspartic acid-based laundry detergent was the first laundry detergent in the world to receive the EU flower ecolabel. [44] Calcium binding ability of polyaspartic acid has been exploited for targeting of drug-loaded nanocarriers to bone. [45] Preparation of hydrogels based on polyaspartic acid, in a variety of physical forms ranging from fiber to particle, can potentially enable facile separation of the chelated ions from a solution. [46] Therefore, despite being weaker than EDTA, polyaspartic acid can still be regarded as a viable alternative due to these features as well as biocompatibility, and biodegradability. [47]

S,S-Ethylenediamine-N,N′-disuccinic acid (EDDS)

A structural isomer of EDTA, ethylenediamine-N,N′-disuccinic acid (EDDS) is readily biodegradable at high rate in its S,S form. [48]

Methylglycinediacetic acid (MGDA)

Trisodium dicarboxymethyl alaninate, also known as methylglycinediacetic acid (MGDA), has a high rate of biodegradation at over 68%, but unlike many other chelating agents can degrade without the assistance of adapted bacteria. Additionally, unlike EDDS or IDS, MGDA can withstand higher temperatures while maintaining a high stability as well as the entire pH range.[ citation needed ] MGDA has been shown to be an effective chelating agent, with a capacity for mobilization comparable with that of nitrilotriacetic acid (NTA), with application to water for industrial use and for the removal of calcium oxalate from urine from patients with kidney stones. [49]

Methods of detection and analysis

The most sensitive method of detecting and measuring EDTA in biological samples is selected reaction monitoring capillary electrophoresis mass spectrometry (SRM-CE/MS), which has a detection limit of 7.3 ng/mL in human plasma and a quantitation limit of 15 ng/mL. [50] This method works with sample volumes as small as 7–8 nL. [50]

EDTA has also been measured in non-alcoholic beverages using high performance liquid chromatography (HPLC) at a level of 2.0 μg/mL. [51] [52]

In the movie Blade (1998), EDTA is used as a weapon to kill vampires, exploding when in contact with vampire blood. [53]

Related Research Articles

<span class="mw-page-title-main">Ligand</span> Ion or molecule that binds to a central metal atom to form a coordination complex

In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electron pairs, often through Lewis bases. The nature of metal–ligand bonding can range from covalent to ionic. Furthermore, the metal–ligand bond order can range from one to three. Ligands are viewed as Lewis bases, although rare cases are known to involve Lewis acidic "ligands".

Chelation is a type of bonding of ions and their molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate ligand and a single central metal atom. These ligands are called chelants, chelators, chelating agents, or sequestering agents. They are usually organic compounds, but this is not a necessity.

<span class="mw-page-title-main">Chelation therapy</span> Medical procedure to remove heavy metals from the body

Chelation therapy is a medical procedure that involves the administration of chelating agents to remove heavy metals from the body. Chelation therapy has a long history of use in clinical toxicology and remains in use for some very specific medical treatments, although it is administered under very careful medical supervision due to various inherent risks, including the mobilization of mercury and other metals through the brain and other parts of the body by the use of weak chelating agents that unbind with metals before elimination, exacerbating existing damage. To avoid mobilization, some practitioners of chelation use strong chelators, such as selenium, taken at low doses over a long period of time.

<span class="mw-page-title-main">Gadolinium(III) chloride</span> Chemical compound

Gadolinium(III) chloride, also known as gadolinium trichloride, is GdCl3. It is a colorless, hygroscopic, water-soluble solid. The hexahydrate GdCl3∙6H2O is commonly encountered and is sometimes also called gadolinium trichloride. Gd3+ species are of special interest because the ion has the maximum number of unpaired spins possible, at least for known elements. With seven valence electrons and seven available f-orbitals, all seven electrons are unpaired and symmetrically arranged around the metal. The high magnetism and high symmetry combine to make Gd3+ a useful component in NMR spectroscopy and MRI.

<span class="mw-page-title-main">Nitrilotriacetic acid</span> Chemical compound

Nitrilotriacetic acid (NTA) is the aminopolycarboxylic acid with the formula N(CH2CO2H)3. It is a colourless solid. Its conjugate base nitrilotriacetate is used as a chelating agent for Ca2+, Co2+, Cu2+, and Fe3+.

<span class="mw-page-title-main">Pentetic acid</span> DTPA: aminopolycarboxylic acid

Pentetic acid or diethylenetriaminepentaacetic acid (DTPA) is an aminopolycarboxylic acid consisting of a diethylenetriamine backbone with five carboxymethyl groups. The molecule can be viewed as an expanded version of EDTA and is used similarly. It is a white solid with limited solubility in water.

<span class="mw-page-title-main">Tetrasodium EDTA</span> Chemical compound

Tetrasodium EDTA is the salt resulting from the neutralization of ethylenediaminetetraacetic acid with four equivalents of sodium hydroxide (or an equivalent sodium base). It is a white solid that is highly soluble in water. Commercial samples are often hydrated, e.g. Na4EDTA.4H2O. The properties of solutions produced from the anhydrous and hydrated forms are the same, provided they are at the same pH.

<span class="mw-page-title-main">EDDS</span> Chemical compound

Ethylenediamine-N,N'-disuccinic acid (EDDS) is an aminopolycarboxylic acid. It is a colourless solid that is used as chelating agent that may offer a biodegradable alternative to EDTA, which is currently used on a large scale in numerous applications.

<span class="mw-page-title-main">Metal toxicity</span> Harmful effects of certain metals

Metal toxicity or metal poisoning is the toxic effect of certain metals in certain forms and doses on life. Some metals are toxic when they form poisonous soluble compounds. Certain metals have no biological role, i.e. are not essential minerals, or are toxic when in a certain form. In the case of lead, any measurable amount may have negative health effects. There is a popular misconception that only heavy metals can be toxic, but lighter metals such as beryllium and lithium can be toxic too. Not all heavy metals are particularly toxic, and some are essential, such as iron. The definition may also include trace elements when abnormally high doses may be toxic. An option for treatment of metal poisoning may be chelation therapy, a technique involving the administration of chelation agents to remove metals from the body.

<span class="mw-page-title-main">EDDHA</span> Chemical compound

EDDHA or ethylenediamine-N,N′-bis(2-hydroxyphenylacetic acid) is a chelating agent. Like EDTA, it binds metal ions as a hexadentate ligand, using two amines, two phenolate centers, and two carboxylates as the six binding sites. The complexes are typically anionic. The ligand itself is a white, water-soluble powder. Both the free ligand and its tetraanionic chelating agent are abbreviated EDDHA. In contrast to EDDHA, most related aminopolycarboxylic acid chelating agents feature tertiary amines and few have phenolate groups.

<span class="mw-page-title-main">Denticity</span> Number of atoms in a ligand that bond to the central atom of a coordination complex

In coordination chemistry, denticity refers to the number of donor groups in a given ligand that bind to the central metal atom in a coordination complex. In many cases, only one atom in the ligand binds to the metal, so the denticity equals one, and the ligand is said to be monodentate. Ligands with more than one bonded atom are called polydentate or multidentate. The denticity of a ligand is described with the Greek letter κ ('kappa'). For example, κ6-EDTA describes an EDTA ligand that coordinates through 6 non-contiguous atoms.

In coordination chemistry, a stability constant is an equilibrium constant for the formation of a complex in solution. It is a measure of the strength of the interaction between the reagents that come together to form the complex. There are two main kinds of complex: compounds formed by the interaction of a metal ion with a ligand and supramolecular complexes, such as host–guest complexes and complexes of anions. The stability constant(s) provide(s) the information required to calculate the concentration(s) of the complex(es) in solution. There are many areas of application in chemistry, biology and medicine.

<span class="mw-page-title-main">Aminopolycarboxylic acid</span>

An aminopolycarboxylic acid is a chemical compound containing one or more nitrogen atoms connected through carbon atoms to two or more carboxyl groups. Aminopolycarboxylates that have lost acidic protons form strong complexes with metal ions. This property makes aminopolycarboxylic acids useful complexone in a wide variety of chemical, medical, and environmental applications.

In chemistry, binding selectivity is defined with respect to the binding of ligands to a substrate forming a complex. Binding selectivity describes how a ligand may bind more preferentially to one receptor than another. A selectivity coefficient is the equilibrium constant for the reaction of displacement by one ligand of another ligand in a complex with the substrate. Binding selectivity is of major importance in biochemistry and in chemical separation processes.

<span class="mw-page-title-main">Ascorbate ferrireductase (transmembrane)</span> Class of enzymes

Ascorbate ferrireductase (transmembrane) (EC 1.16.5.1, cytochrome b561) is an enzyme with systematic name Fe(III):ascorbate oxidorectuctase (electron-translocating). This enzyme catalyses the following chemical reaction

Lanthanide probes are a non-invasive analytical tool commonly used for biological and chemical applications. Lanthanides are metal ions which have their 4f energy level filled and generally refer to elements cerium to lutetium in the periodic table. The fluorescence of lanthanide salts is weak because the energy absorption of the metallic ion is low; hence chelated complexes of lanthanides are most commonly used. The term chelate derives from the Greek word for “claw,” and is applied to name ligands, which attach to a metal ion with two or more donor atoms through dative bonds. The fluorescence is most intense when the metal ion has the oxidation state of 3+. Not all lanthanide metals can be used and the most common are: Sm(III), Eu(III), Tb(III), and Dy(III).

<span class="mw-page-title-main">Ferric EDTA</span> Chemical compound

Ferric EDTA is the coordination complex formed from ferric ions and EDTA. EDTA has a high affinity for ferric ions. It gives yellowish aqueous solutions.

<span class="mw-page-title-main">Beta-propeller phytase</span> Group of enzymes

β-propeller phytases (BPPs) are a group of enzymes (i.e. protein superfamily) with a round beta-propeller structure. BPPs are phytases, which means that they are able to remove (hydrolyze) phosphate groups from phytic acid and its phytate salts. Hydrolysis happens stepwise and usually ends in myo-inositol triphosphate product which has three phosphate groups still bound to it. The actual substrate of BPPs is calcium phytate and in order to hydrolyze it, BPPs must have Ca2+ ions bound to themselves. BPPs are the most widely found phytase superfamily in the environment and they are thought to have a major role in phytate-phosphorus cycling in soil and water. As their alternative name alkaline phytase suggests, BPPs work best in basic (or neutral) environment. Their pH optima is 6–9, which is unique among the phytases.

Transition metal amino acid complexes are a large family of coordination complexes containing the conjugate bases of the amino acids, the 2-aminocarboxylates. Amino acids are prevalent in nature, and all of them function as ligands toward the transition metals. Not included in this article are complexes of the amides and ester derivatives of amino acids. Also excluded are the polyamino acids including the chelating agents EDTA and NTA.

Chelated platinum is an ionized form of platinum that forms two or more bonds with a counter ion. Some platinum chelates are claimed to have antimicrobial activity.

References

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  2. ↑ Raaflaub, Jürg (1956). "Applications of Metal Buffers and Metal Indicators in Biochemistry". Methods of Biochemical Analysis. Vol. 3. pp. 301–325. doi:10.1002/9780470110195.ch10. ISBN   978-0-470-30492-1. PMID   13369167.
  3. ↑ Substance Name: Sodium calcium edetate. NIH.gov
  4. 1 2 3 4 Hart, J. Roger (2005). "Ethylenediaminetetraacetic Acid and Related Chelating Agents". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a10_095. ISBN   978-3527306732.
  5. ↑ Furia, T. (1964). "EDTA in Foods – A technical review". Food Technology. 18 (12): 1874–1882.
  6. ↑ Taylor, H. F. W. (1990). Cement Chemistry. Academic Press. ISBN   978-0-12-683900-5.
  7. ↑ Norvell, W. A.; Lindsay, W. L. (1969). "Reactions of EDTA Complexes of Fe, Zn, Mn, and Cu with Soils". Soil Science Society of America Journal. 33 (1): 86. Bibcode:1969SSASJ..33...86N. doi:10.2136/sssaj1969.03615995003300010024x.
  8. ↑ Powell, J. E.; Spedding, F. H. (1956). Basic Principles Involved in the Macro-Separation of Adjacent Rare Earths from Each Other by Means of Ion Exchange (Technical report). Iowa State College. doi: 10.2172/4289324 . OSTI   4289324 . S2CID   93195586.
  9. ↑ DeBusk, Ruth; et al. (2002). "Ethylenediaminetetraacetic acid (EDTA)". University of Maryland Medical Center. Archived from the original on 2007-05-04.
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  25. ↑ US 2130505, Münz, Ferdinand,"Polyamino carboxylic acids and process of making same",published 1938-09-20, assigned to General Aniline Works Ltd. . Also DE 718981, Münz, Ferdinand,"Verfahren zum Unschädlichmachen der Härtebildner des Wassers [Process for rendering the hardness components of water harmless]",published 1938-09-20, assigned to I. G. Farbenindustrie
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