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ligand
ligand , charged or uncharged molecule with one or more unshared pairs of electrons that can attach to a central metallic atom or ion to form an aggregate known as a complex ion (see chemical bond ). Some ligands that share electrons with metals form very stable complexes. Some common bases that act as ligands are water and ammonia molecules and halide, hydroxide, acetate, cyanide, thiocyanate, and nitrite anions . These ligands are monofunctional, i.e., they are attached by one unshared pair of electrons during complexing. Polyfunctional ligands, which bind to the metal ion with two or more pairs of electrons, are called chelates (see chelating agents ). Ethylenediamine-tetraacetate, a commonly used chelating compound, has six pairs of electrons to bind to metal ions. Electron-donating functional groups containing nitrogen, oxygen, sulfur, phosphorous, or carbon may act as ligands in complex biological systems. For example, in enzymes that need complexed metal ions to function, mercapto (sulfur-containing) groups and amino (nitrogen-containing) groups act as chelating agents; these groups fix the metal ion in a specific position. Other biologically important molecules, such as chlorophyll, vitamin B 12 , and heme, also have nitrogen-containing groups that donate electrons and have a chelating function. |
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"ligand." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "ligand." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1E1-ligand.html "ligand." The Columbia Encyclopedia, 6th ed.. 2011. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-ligand.html |
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ligand
ligand
1. (in chemistry) An ion, atom, or molecule that donates a pair of electrons to a metal atom to form a type of covalent bond called a coordinate bond. 2. (in cell biology) A molecule that binds to a protein with a high degree of specificity. Examples are the substrate of an enzyme and a hormone binding to a cell receptor. |
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"ligand." A Dictionary of Biology. 2004. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "ligand." A Dictionary of Biology. 2004. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O6-ligand.html "ligand." A Dictionary of Biology. 2004. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O6-ligand.html |
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ligand
ligand
1. An atom, ion, or molecule that acts as the electron-donor partner in one or more co-ordination bonds. A heterocyclic ring is formed if the ligand is an organic compound, and the product is termed a chelate. 2. A molecule (e.g. an antibody) that can bind to specific sites on cell membranes. |
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MICHAEL ALLABY. "ligand." A Dictionary of Plant Sciences. 1998. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "ligand." A Dictionary of Plant Sciences. 1998. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O7-ligand.html MICHAEL ALLABY. "ligand." A Dictionary of Plant Sciences. 1998. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O7-ligand.html |
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ligand
ligand Atom, ion, or molecule that acts as the electron-donor partner in one or more coordination bonds. A heterocyclic ring is formed if the ligand is an organic compound, and the product is termed a chelate. See also CHELATION; and COORDINATION NUMBER.
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AILSA ALLABY and MICHAEL ALLABY. "ligand." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "ligand." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O13-ligand.html AILSA ALLABY and MICHAEL ALLABY. "ligand." A Dictionary of Earth Sciences. 1999. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-ligand.html |
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ligand
ligand An atom, ion, or molecule that acts as the electron-donor partner in one or more co-ordination bonds. A hetero-cyclic ring is formed if the ligand is an organic compound, and the product is termed a chelate.
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MICHAEL ALLABY. "ligand." A Dictionary of Zoology. 1999. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "ligand." A Dictionary of Zoology. 1999. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O8-ligand.html MICHAEL ALLABY. "ligand." A Dictionary of Zoology. 1999. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O8-ligand.html |
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ligand
ligand (lig-ănd) n. a molecule that binds to another molecule, as in antigen–antibody and hormone–receptor bondings.
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"ligand." A Dictionary of Nursing. 2008. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "ligand." A Dictionary of Nursing. 2008. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O62-ligand.html "ligand." A Dictionary of Nursing. 2008. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O62-ligand.html |
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ligand
ligand •unironed, viand
•prebend
•beribboned, riband
•husband • house husband
•unquestioned • escutcheoned
•brigand, ligand
•legend
•fecund, second, split-second
•millisecond • nanosecond
•microsecond • rubicund • jocund
•Langland • garland • parkland
•Cartland, heartland
•headland • Shetland • Lakeland
•mainland
•eland, Leland, Wieland, Zealand, Zeeland
•Greenland • heathland • Cleveland
•Friesland • Queensland • midland
•England • Finland • Maryland
•dryland, highland, island
•Iceland • Holland • dockland
•Scotland
•foreland, Westmorland
•Auckland, Falkland
•Portland • Northland
•lowland, Poland, Roland
•Oakland • Copland • Newfoundland
•woodland • Buckland • upland
•Jutland, Rutland
•Ireland • moorland
•Cumberland, Northumberland
•Sunderland • Switzerland
•Sutherland • Hammond
•almond, Armand
•Edmund, Redmond
•Desmond, Esmond
•Raymond • Grimond • Richmond
•Sigmund • Sigismund • Osmond
•Dortmund • unsummoned
•diamond • gourmand • unopened
•errand, gerund
•reverend • Bertrand • dachshund
•unchastened
•old-fashioned, unimpassioned
•unsanctioned
•aforementioned, undermentioned, unmentioned
•unconditioned • unsweetened
•unenlightened • unleavened
•self-governed • unseasoned
•wizened • thousand
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"ligand." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "ligand." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O233-ligand.html "ligand." Oxford Dictionary of Rhymes. 2007. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O233-ligand.html |
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