about ligands in inorganic chemistry ligands in biochemistry Ligand biochemistry other uses Ligand disambiguation ... 4 sub with five ligands In coordination chemistry , a ligand is an ion or molecule see also functional ... metal and ligand generally involves formal donation of one or more of the ligand s electron pairs. The nature of metal ligand bonding can range from covalent bond covalent to ionic. Furthermore, the metal ligand bond order can range from one to three. Ligands are viewed as Lewis acids and bases Lewis ... the reactivity chemistry reactivity of the central atom, including ligand substitution rates, the reactivity of the ligands themselves, and redox . Ligand selection is a critical consideration in many ... denticity or hapticity . The size of a ligand is indicated by its Ligand cone angle cone angle .... The first to use the term ligand were Alfred Stock and Carl Somiesky, in relation to silicon chemistry ... one ranking system focuses on ligand hardness see also HSAB theory hard soft acid base theory . Metal ... of the ligand should have an energy that overlaps with the LUMO Lowest Unoccupied Molecular ..., sub o sub . The magnitude of sub o sub is determined by the field strength of the ligand ... now be sorted according to the magnitude of sub o sub see the table Ligand Examples of common ligands .... The arrangement of the d orbitals on the central atom as determined by the strength of the ligand ... where the ligand has low energy LUMO, such orbitals also participate in the bonding. The metal ligand bond can be further stabilised by a formal donation of electron density back to the ligand in a process ... into the LUMO of the coordinated ligand. Carbon monoxide is the preeminent example a ligand that engages ... is a hexadentate chelating ligand. Image CoA6Cl3.png thumb 120px Cobalt III complex containing six ammonia ligands, which are monodentate. The chloride is not a ligand. Classification of ligands ... sub 3 sub sub 2 sub . EDTA sup 4 sup is classified as an L sub 2 sub X sub 4 sub ligand, as it features ... more details
Ligand may refer to Ligand , an atom, ion, or functional group that donates one or more of its electrons through a coordinate covalent bond to one or more central atoms or ions Ligand biochemistry , a substance that binds to a protein a guest in host guest chemistry disambig fr Ligand sr Ligand vi ezna na odrednica tr Ligand ur ... more details
Unreferenced stub auto yes date December 2009 Orphan date November 2006 Ligand isomerism is a type of structural isomer ism which arises from the presence of ligand s which can adopt different isomeric forms. An example is provided by diaminopropane,which may have amine groups in terminal 1,3 positions or in the 1,2 positions. The position isomer of ligand gives ligand isomerism. DEFAULTSORT Ligand Isomerism Category Chemical bonding Chem stub ... more details
protein Name tumor necrosis factor ligand superfamily, member 9 caption image width HGNCid 11939 Symbol TNFSF9 AltSymbols EntrezGene 8744 OMIM 606182 RefSeq NM 003811 UniProt P41273 PDB ECnumber Chromosome 19 Arm p Band 13.3 LocusSupplementaryData 4 1BB ligand is a type 2 transmembrane glycoprotein belonging to the Tumor necrosis factors TNF superfamily, expressed on activated T Lymphocytes ref cite book last Lotze first Michael title Dendritic Cells publisher Academic Press location Boston year 2001 isbn 0 12 455851 8 ref . See also CD137 References reflist External links MeshName 4 1BB Ligand Glycoproteins Tumor necrosis factors biochemistry stub sr 4 1BB ligand ... more details
other uses of Ligand Image Myoglobin and heme.png thumb 300px right Myoglobin blue with its ligand heme orange bound. Based on PDB 1MBO In biochemistry and pharmacology , a ligand from the Latin ligandum ... . Actual irreversible covalent binding between a ligand and its target molecule is rare in biological ... whether the ligand actually binds at a metal site, as is the case in hemoglobin . Ligand binding ... ligand binding affinity affinity . Radioligand s are radioisotope labeled compounds and used in vivo ... studies . Receptor ligand binding affinity The interaction of most ligands with their binding sites can be characterized in terms of a binding affinity. In general, high affinity ligand binding results from greater intermolecular force between the ligand and its receptor while low affinity ligand binding involves less intermolecular force between the ligand and its receptor. In general, high affinity binding involves a longer residence time for the ligand at its receptor binding site than is the case ..., resulting in altered behavior of an associated Ligand gated ion channel ion channel or enzyme . File Agonist 2.png thumb Two agonists with similar binding affinity A ligand that can bind to a receptor ... to produce the physiological response. High affinity ligand binding implies that a relatively low concentration of a ligand is adequate to maximally occupy a ligand binding site and trigger a physiological response. Low affinity binding implies that a relatively high concentration of a ligand is required before the binding site is maximally occupied and the maximum physiological response to the ligand ... receptor binding affinity. In the example shown to the left, ligand binding curves are shown for two ligands with different binding affinities. Ligand binding is often characterized in terms of the concentration of ligand at which half of the receptor binding sites are occupied, known as the dissociation constant K sub d sub . The ligand illustrated by the red curve has a higher binding ... more details
In chemistry a chiral ligand is a specially adapted ligand used for asymmetric synthesis . This ligand is an enantiopure organic compound which combines with a metal center by chelation to form an asymmetric catalyst . This catalyst engages in a chemical reaction and transfers its chirality to the reaction product which as a result also becomes chiral. In an ideal reaction one equivalent of catalyst can turnover number turn over many more equivalents of reactant which enables the synthesis of a large amount of a chiral compound from achiral precursors with the aid of a very small often expensive chiral ligand. First discovery The first such ligand, the phosphine diphosphine DiPAMP was developed in 1968 by William S. Knowles of Monsanto Company , who won the 2001 Nobel Prize in Chemistry , ref Nobel prize 2001 www.nobelprize.org http nobelprize.org nobel prizes chemistry laureates 2001 public.html ... ref Important members depicted below are BINOL , BINAP , TADDOL , DIOP , bisoxazoline ligand BOX and DuPhos a phosphine ligand , all available as enantiomeric pairs. Image ChiralLigands.png 400px A selection of chiral ligands Other members are Salen ligand Salen , cinchona alkaloid s and phosphoramidite ... the reaction coordinate . The image depicted on the right gives a general idea how a chiral ligand may induce an enantioselective reaction. The ligand in green has C2 symmetry with its nitrogen, oxygen or phosphorus atoms hugging a central metal atom in red . In this particular ligand the right side ... in blue a hydride ion. In absence of the metal and the ligand the re face approach of the hydride ... mixture like expected . The ligand metal presence changes all that. The carbonyl group will coordinate ..., and Kenji Itoh Organometallics 1989 8 3 pp 846 848 DOI 10.1021 om00105a047 ref Note that when the ligand is replaced by its mirror image the other enantiomer will form and that a racemic mixture of ligand ... References reflist Chiral synthesis DEFAULTSORT Chiral Ligand Category Stereochemistry Category ... more details
Ligand efficiency is a measurement the binding energy per atom of a ligand to its binding partner, such as a receptor or enzyme. ref cite journal journal Proc Natl Acad Sci U S A. year 1999 volume 96 issue 18 pages 9997 10002 title The maximal affinity of ligands author I. D. Kuntz, K. Chen, K. A. Sharp, and P. A. Kollman pmc 17830 doi 10.1073 pnas.96.18.9997 pmid 10468550 ref Ligand efficiency is used in drug discovery research programs to assist in narrowing focus to lead compound s with optimal combinations of physicochemical properties and pharmacological properties. ref cite journal doi 10.1016 S1359 6446 05 03386 6 title Ligand efficiency indices as guideposts for drug discovery year 2005 last1 Abadzapatero first1 C last2 Metz first2 J journal Drug Discovery Today volume 10 issue 7 pages 464 469 pmid 15809192 ref Mathematically, ligand efficiency LE can be defined as the ratio of Gibbs free energy G to the number of non hydrogen atoms of the compound LE G N where G RTlnK sub i sub and N is the number of non hydrogen atoms. ref Cite journal doi 10.1016 S1359 6446 04 03069 7 title Ligand efficiency A useful metric for lead selection year 2004 last1 Hopkins first1 Andrew L. last2 Groom first2 Colin R. last3 Alex first3 Alexander journal Drug Discovery Today volume 9 issue 10 pages 430 431 pmid 15109945 ref See also Drug design Drug discovery hit to lead References reflist Medicinal chemistry Category Drug discovery Category Medicinal chemistry ... more details
In biochemistry , a protein ligand is an atom , a molecule or an ion which can bind to a specific site the binding site on a protein. Alternative names used to mean a protein ligand are affinity reagents or protein binders. To date, antibodies are the most widely used protein ligands in life science investigations, however, other molecules such as Scaffold protein protein scaffolds , nucleic acids , peptides are also being used. ref Taussig MJ et al, 2007. ProteomeBinders planning a European resource of affinity reagents for analysis of the human proteome. Nat Methods. 2007 Jan 4 1 13 7. ref Main methods to study protein ligand interactions are principal hydrodynamic and calorimetric techniques, and principal spectroscopic and structural methods such as Fourier transform spectroscopy Raman spectroscopy Fluorescence spectroscopy Circular dichroism Nuclear magnetic resonance Mass spectrometry Atomic force microscope Paramagnetic probes Dual Polarisation Interferometry Other techniques include fluorescence intensity, bimolecular fluorescence complementation, FRET fluorescent resonance energy transfer FRET quenching surface plasmon resonance, Bio Layer Interferometry , Coimmunopreciptation indirect ELIS, equilibrium dialysis, gel electrophoresis, far western blot, fluorescence polarization anisotropy, electron paramagnetic resonance, Microscale Thermophoresis The dramatically increased computing power of supercomputers and personal computers has made it possible to study protein ligand interactions also by means of computational chemistry . For example, a worldwide grid of well over a million ordinary PCs was harnessed for cancer research in the project grid.org , which ended in April 2007. Grid.org has been succeeded by similar projects such as World Community Grid , Human Proteome Folding Project , Compute Against Cancer and Folding Home . References references DEFAULTSORT Protein Ligand Category Biomolecules Category Chemical bonding Category Proteins ... more details
1967, pg. 72. ref The term scorpionate comes from the fact that the ligand can bind a metal with two ... to explore the possibilities of scorpionate ligand alternatives, such as utilizing pyrrole , imidazole ... ligands such as N sub 4 sub O sub 3 sub from the ligand tris 6 2 N,N diethylcarbamoyl pyridyl methyl amine Sulfur donor groups such as those found in the Tm ligand or oxygen donor groups. ref http pubs.acs.org ... complexes. It was soon understood by many organometallic chemists that a Cp ligand is isolobal to Tp ... Tp and more recently Tm as a co ligand on the metal. The Tp, Tm, trithia 9 crown 3 a sulfur version ... and platinum it is possible to turn the Tm ligand inside out to form a borane to which the metal ... TmMntricarbonyl.jpg center 300px Tp class main Tp ligands The tris pyrazolyl borate ligand is often ... allow simpler and more accurate methods to be developed. ligand s allow for good shielding of the bound ... . Tm class Main Tm ligands By replacing the nitrogen donor of a Tp ligand atoms with sulfur atoms, a class ... on this ligand class. To form NaTm Na sup sup HB mt sub 3 sub sup sup , Methimazole and sodium borohydride ... be reacted with salicylaldehyde to form a ligand which can bind with three oxygens and three nitrogens ... Ligand Category Coordination chemistry Category Tripodal ligands ... more details
In chemistry , bisoxazoline ligands BOX ligands for short are chiral ligand s based on a bis oxazoline skeleton and used in combination with a metal compound in asymmetric synthesis as a chiral catalyst ref Bisoxazoline BOX Ligand Metal Complexes An Emerging Chiral Catalyst Ramkrishna Basak Synlett 2003 ... for instance from naturally occurring chiral amino acid s. The Noyori ligand ref Homogeneous catalysis ... Image NoyoriChiralLigandSynthesis.png 400px Noyori ligand synthesis 1968 valign top Image AsymmetricSynthesisNoyori.png 400px Noyori cyclopropanation 1968 Noyori ligand synthesis 1968 Noyori cyclopropanation ..., Y. Yoneyoshi and T. Nagase ref used a similar ligand in the asymmetric cyclopropanation of another diene to the insecticide chrysanthemic acid . His ligand was derived from reaction of salicylaldehyde ... alanine . align center class wikitable Image ArataniLigandSynthesis.png 400px Aratani ligand ... 1975 Aratani ligand synthesis 1975 Aratani cyclopropanation 1975 In 1984 Brunner ref Asymmetric syntheses ... describes a nitrogen nitrogen bidentate ligand with a pyridine group fused to a thiazolidine group ... 826 DOI 10.1021 om00105a039 ref and demonstrated the new ligand in a monophenylation of a diol by the organobismuth ... Itoh Organometallics 1989 8 3 pp 846 848 DOI 10.1021 om00105a047 ref . With three nitrogen atoms this ligand ... 350px Bisoxazoline ligand in cyclopropanation valign top Image BOXmasamune.png 350px Bisoxazoline ligand in cyclopropanation Evans 1991 ref Asymmetric cyclopropanation of styrene with an diazo compound catalysed by copper I triflate tBuBOX ref Bisoxazoline ligand in cyclopropanation ... to display enantioselectivity when performed in presence of a BOX ligand. The obvious targets are 100 enantiomeric excess ee with the use of as little as possible amounts of metal and ligand, usually between 0.01 equivalent and 0.1 equivalent. Selecting the ligand most suitable for a particular reaction ... ref References Reflist DEFAULTSORT Bisoxazoline Ligand Category Isoxazoles ... more details
A bridging ligand is a ligand that connects two or more atoms, usually metal ions. ref GoldBookRef title bridging ligand url http goldbook.iupac.org B00741.html ref The ligand may be atomic or polyatomic. Virtually all complex organic compounds can serve as bridging ligands, so the term is usually restricted to small ligands such as pseudohalides or to ligands that are specifically designed to link two metals. In naming a complex wherein a single atom bridges two metals, the bridging ligand is preceded by Mu chemistry ref GoldBookRef title mu url http goldbook.iupac.org M03659.html ref with a superscript number denoting the number of metals bound to the bridging ligand is bound. sup 2 sup is often denoted simply as . Image Bridgingligand.png thumb 200px Right An example of a &mu sup 2 sup bridging ligand Illustrative bridging ligands Virtually all ligands are known to bridge, with the exception of amines and ammonia. ref cite journal last Werner first H. year 2004 title The Way into the Bridge A New Bonding Mode of Tertiary Phosphanes, Arsanes, and Stibanes journal Angew. Chem. Int. Ed. volume 43 pages 938 954 doi 10.1002 anie.200300627 pmid 14966876 issue 8 ref Particularly common inorganic bridging ligands include hydroxide OH sup sup , oxide O sup 2 sup , sulfide S sup 2 sup , bisulfide SH sup sup , amido NH sub 2 sub sup sup NH sup 2 sup imido N sup 3 sup nitrido Carbon monoxide CO Halide s Hydride Cyanide Cyanide usually bridges via M NC M linkages, unlike the other entries on this list. Many organic ligands form strong bridges between metal centers. Many common examples include derivatives of the above inorganic ligands R alkyl, aryl alkoxide OR sup sup , thiolate SR sup sup , amido NR sub 2 sub sup sup NR sup 2 sup imido P sup 3 sup phosphido PR sub 2 sub sup ... In this example hydroxide plays the role of a sup 2 sup bridging ligand. Notice in the name of the compound ... carbyne ligand C t Bu . References references Category Coordination chemistry zh ... more details
Orphan date January 2011 The Kl ui ligand is the anion C sub 5 sub H sub 5 sub Co CH sub 3 sub O sub 2 sub PO sub 3 sub sup sup . The ligand , popularlized by Wolfgang Kl ui, binds metals and metalloids via a facial O sub 3 sub donor set. Related tridentate anionic ligands include trispyrazolylborate and cyclopentadienyl anions. ref Wolfgang Kl ui, N. Mocigemba, A. Weber Schuster, R. Bell, W. Frank, D. Mootz, W. Poll, and H. Wunderlich C sub 5 sub H sub 5 sub Co P O OH sub 2 sub sub 3 sub H A Novel Organometallic Tris phosphonic Acid that Dissolves Glass to Form a Six Coordinate Silicon Complex Chemistry European Journal 2002, Volume 8, pages 2335 2340. DOI 10.1002 1521 3765 20020517 8 10 2335 AID CHEM2335 3.0.CO 2 P ref image KlauiCmpx.png thumb 160px right General structure of a metal center coordinated to a sup 3 sup Kl ui ligand. The ligand is derived from the cationic complex of trimethylphosphite C sub sub 5 sub sub H sub sub 5 sub sub Co P OCH sub sub 3 sub sub sub sub 3 sub sub sub sub 3 sub sub sup 2 sup via an Arbuzov reaction . Using other phosphites and other cyclopentadienyl ligands, a large variety of derivatives are possible. The parent acid C sub 5 sub H sub 5 sub Co CH sub 3 sub O sub 2 sub PO sub 3 sub H is highly soluble in water 270 g 100 mL . Its p K sub a sub is about 2. Many complexes have been described, including bis chelate complexes of the type M C sub 5 sub H sub 5 sub Co CH sub 3 sub O sub 2 sub PO sub 3 sub sub 2 sub sup n sup M Co II , Mn II , Bi III , etc. . ref Wolfgang Kl ui, Heiko Otto, Werner Eberspach, Elke Buchholz Die Michaelis Arbusov Reaktion als Zugang zu neuen Sauerstoff Tripodliganden des Typs C sub 5 sub R sub 5 sub M P O OCH sub 3 sub sub 2 sub sub 3 sub sup sup . Ligandfeldspektroskopische und koordinationschemische Charakterisierung ... ref References references DEFAULTSORT Klaui Ligand Category Cobalt compounds de Kl ui Tripod Ligand ... more details
PBB geneid 356 Fas ligand FasL or CD95 L is a type II transmembrane protein that belongs to the Tumor ... . Fas ligand receptor interactions play an important role in the regulation of the immune system and the progression of cancer . Structure Fas ligand or FasL is a Homotrimer homotrimeric type II transmembrane ... cell. This trimerization usually leads to apoptosis, or cell death. Soluble Fas ligand ... bound Fas ligand and rendering them inactive. ref name pmid10942251 cite journal author Sheikh MS, Fornace ... the Death inducing signaling complex death inducing signaling complex DISC upon ligand binding. Membrane anchored Fas ligand trimer on the surface of an adjacent cell causes trimerization of Fas receptor ... pathways involved in apoptosis Apoptosis triggered by Fas Fas ligand binding plays a fundamental ... of T cells leads to their expression of the Fas ligand. T cells are initially resistant to Fas mediated ... mutations of Fas or Fas ligand develop an accumulation of aberrant T cells, leading to lymphadenopathy ... privileged areas such as the cornea or testes express Fas ligand and induce the apoptosis of infiltrating ... of immune privilege. Maternal tolerance Fas ligand may be instrumental in the prevention of leukocyte ... attributed to a faulty Fas Fas ligand system. Tumor counterattack Tumors may over express Fas ligand ... 2005 pmid 15889255 doi 10.1007 s00262 005 0680 7 ref The up regulation of Fas ligand often occurs ... disorder of apoptosis. Interactions Fas ligand has been shown to Protein protein interaction ... Mollinedo Faustino year 2005 month Mar. title Cytoskeleton mediated death receptor and ligand ... polyproline region of CD95 ligand CD178 journal FEBS Lett. volume 519 issue 1 3 pages 50 58 ... of the cytosolic polyproline region of the CD95 ligand hints for the reverse signal transduction capacity ... P A year 1997 month Apr. title Identification of amino acid residues important for ligand binding ..., Tschopp J year 1997 month Jul. title Characterization of Fas Apo 1, CD95 Fas ligand interaction journal ... more details
Infobox Company company name Inte Ligand company logo Image Inteligand.jpg vector logo company type Private genre foundation 2003 founder location city Vienna location country Austria location origins key people Prof. Thierry Langer, Dr. Gerhard Wolber, Prof. Hermann Stuppner area served industry Life sciences products revenue operating income net income num employees parent divisions subsid owner company slogan homepage http www.inteligand.com www.inteligand.com dissolved footnotes Inte Ligand is a software company headquartered in Vienna , Austria . It provides software and services for chemical research, especially in the areas of drug discovery . Inte Ligand started in 2003 as a spin off of the University of Innsbruck and was founded by Prof. Thierry Langer, Dr. Gerhard Wolber and Prof. Hermann Stuppner. Researchers and scientists at Inte Ligand have developed technology ref Wolber, G. Langer, T. LigandScout 3 D pharmacophores derived from protein bound ligands and their use as virtual screening filters J. Chem. Inf. Model 2005 45 1 160 169. http dx.doi.org 10.1021 ci049885e DOI 10.1021 ci049885e ref ref Wolber, G. Dornhofer, A. A. Langer, T. Efficient overlay of small organic molecules using 3D pharmacophores J. Comput. Aided Mol. Des. 2007 20 12 773 788. http dx.doi.org 10.1007 s10822 006 9078 7 DOI 10.1007 s10822 006 9078 7 ref for 3D pharmacophore development and virtual screening used in early drug development stages to make drug discovery more efficient to prevent failures in clinical trials. Applications include the discovery of new Myeloperoxidase ligands, ref Malle, E. Furtm ller P. G. Sattler, W. Obinger C. Myeloperoxidase a target for new drug development? British Journal of Pharmacology 2007 152, 838 854. http dx.doi.org 10.1038 sj.bjp.0707358 DOI 10.1038 ... Inte Ligand official homepage http macresearch.org review ligandscout A review of LigandScout ... Companies established in 2003 it Inte Ligand ... more details
In coordination chemistry , an oxo ligand is an oxygen atom bound only to one or more metal centers. These ligands can exist as terminal or most commonly as bridging atom Fig. 1 . Oxo ligands stabilize high oxidation states of a metal. ref name M L bonds Nugent, W. A., Mayer, J. M. Metal Ligand Multiple Bonds. John Wiley & Sons, New York, 1988. ref Image Bridging&terminal oxo ligands.png thumb 200px right Fig. 1 a Doubly bridging ligand bridging and b terminal oxo ligands. Oxo ligands are pervasive, comprising the great majority of the Earth s crust. This article concerns a subset of oxides, molecular derivatives. They are also found in several metalloenzymes, e.g. in the molybdenum cofactor and in many iron containing enzymes. One of the earliest synthetic compounds to incorporate an oxo ligand is sodium ferrate Na sub 2 sub FeO sub 4 sub circa 1702. ref name Sharpless 1971 cite journal author Sharpless, K.B. Flood, T.C. title Oxotransition metal oxidants as mimics for the action of mixed function oxygenases. NIH shift with chromyl reagents journal J. Am. Chem. Soc. pmid 5553075 year 1971 volume 93 issue 9 pages 2316 8 doi 10.1021 ja00738a039 ref Reactivity Olation and acid base reactions ... is shown for the other two cofactors. The oxo ligand or analagous sulfido ligand is nearly ubiquitous ... beyond 4. A correlary is that the reactivity of complexes containing a terminal oxo ligand depends on the metal d electron count. For octahedral d sup 4 sup oxo complexes, the oxo ligand is nucleophilic ... numbers lower than 6. This trend holds for other metal ligand multiple bonds. Terminal ... orbitals and destabilization of the metal oxygen Metal ligand multiple bond multiple bond see ... Polytungstate Ligand journal J. Am. Chem. Soc. year 2005 volume 127 pages 11948 11949 doi ... 2004 volume 306 pages 2074 2077 doi 10.1126 science.1104696 issue 5704 ref See also metal ligand multiple ... Oxo Ligand Category Ligands Category Oxides ... more details
In chemistry , a pincer ligand is a type of chelation chelating agent that binds tightly to three adjacent coplanar sites, usually on a transition metal in a meridional configuration. ref The Chemistry of Pincer Compounds Morales Morales, D. Jensen, C., Eds. Elsevier Science Amsterdam, 2007. ISBN 10 0444531386 ref The inflexibility of the pincer metal interaction confers high thermal stability to the resulting complexes. This stability is in part ascribed to the constrained geometry of the pincer, which inhibits Metallocycle cyclometallation of the organic substituents on the donor sites at each end. In the absence of this effect, cyclometallation is often a significant deactivation process for complexes, in particular limiting their ability to effect C H bond activation . The organic substituents also define a hydrophobic pocket around the reactive coordination site. Stoichiometric and catalytic applications of pincer complexes have been studied at an accelerating pace since the mid 1970 s. Most pincer ligands contain phosphines . ref name Jens Jensen, C. M., Iridium PCP pincer complexes highly active and robust catalysts for novel homogeneous aliphatic dehydrogenations , Chemical Communications, 1999, 2443 2449. doi 10.1039 a903573g . ref Reactions of metal pincer complexes are localized at three site perpendicular to the plane of the pincer ligand, although in some cases one arm is hemi labile and an additional coordination site is generated transiently. Early examples of pincer ligands not called such originally were anionic with a carbanion as the central donor site and flanking phosphine donors and are referred to as PCP pincers. Scope of pincer ligands Although the most common class of pincer ligands features PCP donor sets, variations have been developed where the phosphines ... sites. The most famous such ligand is terpyridine terpy . Terpy and its relatives lack the steric ..., G. Organometallics 1998, 17, 5647 5655. Category Coordination chemistry de Pincer Ligand ... more details
Orphan date May 2007 There are two types of pathway for subsititution of ligand s in a complex. The ligand dependent pathway is the one whereby the chemical properties of the ligand affect the rate of substitution. Alternatively, there is the ligand independent pathway , which is where the ligand does not have an effect. This is of vital importance in the world of inorganic chemistry and complex ion s. chemistry stub Category Chemical bonding ... more details
Orphan date January 2011 context date September 2010 Ligand K edge X ray absorption spectroscopy XAS is a spectroscopic technique that allows the direct study of metal ligand bonding. ref Cite doi 10.1016 j.ccr.2004.03.020 ref In a XAS experiment, electrons in ligand 1s orbitals are excited to unfilled p principal quantum number n 4 and continuum states. This results in a large spectral feature known as a rising edge. Transitions at energies lower than the edge can occur, provided they are to orbitals with some ligand p character, and are called pre edges. Such transitions are often observed in the data of complexs with metal ligand bonding. Pre edge intensities D sub 0 sub are related to the amount of ligand L character in the unfilled orbital math D 0 L 1s rightarrow psi const vert langle L 1s vert mathbf r vert psi rangle vert 2 alpha 2 const vert langle L 1s vert mathbf r vert L np rangle vert 2 math where math psi math is the wavefunction of the unfilled orbital, r is the transition dipole operator, and math alpha 2 math is the covalency or ligand character in the orbital. Since math psi sqrt 1 alpha 2 vert M d rangle alpha vert L np rangle math , the above expression relating intensity and quantum transition operators can be simplified to use experimental values math D 0 frac alpha 2 h 3n I s math where n is the number of absorbing ligand atoms, h is the number of holes, and I sub s sub is the transition dipole integral which can be determined experimentally. Therefore, by measuring the intensity of pre edges, it is possible to experimentally the determine the amount of ligand character in a molecular orbital. References references Category Spectroscopy Category Synchrotron related techniques Category X rays ... more details
In medicine and pharmacology , a ligand binding assay LBA is a technique to identify the presence of a molecule and quantify it. There are numerous types of ligand binding assays, both radioactive and non radioactive. ref name Sittampalam1997 cite pmid 9667878 ref ref name de Jong2005 cite pmid 16253574 ref ref name Lakowicz1991 Joseph R. Lakowicz. 1991 Topics in Fluorescence Spectroscopy Biochemical applications. ref As such, ligand binding assays are superset of radiobinding assay s, which are the conceptual inverse of radioimmunoassay s RIA . Some newer types are called mix and measure assays because they do not require separation of bound from free ligand. ref name de Jong2005 Historically, LBA techniques were used extensively to quantify hormone or hormone receptor concentrations in plasma or in tissue. The Ligand biochemistry ligand binding assay methodology quantified the concentration of the hormone in the test material by comparing the effects of the test sample to the results of varying amounts of known protein the ligand . A prominent use was the test for Breast cancer classification Receptor status classification of estrogen receptor status ER and progesterone receptor PR in breast cancer breast tumors . The LBA was performed by homogenization of fresh or frozen tumor tissue, incubation of centrifuged cytosol with increasing quantities of radioactive estradiol estradiol 17 , followed by separation of unbound estradiol with dextran coated charcoal DCC to quantify the concentration of high affinity estrogen binding sites ER using standard amounts of known protein. ref name McGuire1973 cite pmid 4345203 ref It was replaced by immunohistochemistry IHC , which may be superior to LBA for assessing estrogen receptor ER status in primary breast cancer because it is easier, safer, and less expensive, and has an equivalent or better ability to predict response to Adjuvant therapy adjuvant endocrine therapy. ref name Harvey1999 cite pmid 10334533 ref ref name Jasani2006 ... more details
Protein ligand docking is a molecular modelling technique. The goal of protein ligand docking is to predict the position and orientation of a ligand biochemistry ligand a small molecule when it is bound to a protein receptor or enzyme. Pharmaceutical research employs docking techniques for a variety of purposes, most notably in the virtual screening of large databases of available chemicals in order to select likely drug candidates. Several protein ligand docking software applications are available, such as AutoDock or http www3.interscience.wiley.com cgi bin abstract 114195671 ABSTRACT EADock . There are also web service http www.dockingserver.com Molecular Docking Server , http swissdock.vital it.ch SwissDock that calculate the site, geometry and energy of small molecules interacting with proteins. Protein Flexibility Computational capacity has increased dramatically over the last decade making possible the use of more sophisticated and computationally intensive methods in computer assisted drug design. However, dealing with receptor flexibility in docking methodologies is still a thorny issue . The main reason behind this difficulty is the large number of degrees of freedom that have to be considered in this kind of calculations. However, neglecting it leads to poor docking results in terms of binding pose prediction in real world settings ref name Cerqueira Cite journal author Cerqueira NM, Fernandes PA, Eriksson LA, Ramos MJ title MADAMM A multistaged docking with an automated molecular modeling protocol journal Proteins Structure, Function, and Bioinformatics volume 74 issue 1 pages 192 206 year 2009 month July doi 10.1002 prot.22146 pmid 18618708 ref . See also Docking molecular Virtual screening External links http users.ox.ac.uk jesu1458 installation of autodock on ubuntu linux installation of autodock on ubuntu linux.htm Step by step installation of MGLTools ... References Reflist DEFAULTSORT Protein Ligand Docking Category Molecular modelling Category Computational ... more details
Ligand field theory LFT describes the bonding, orbital arrangement, and other characteristics of coordination complexes . ref Schl fer, H. L. Gliemann, G. Basic Principles of Ligand Field Theory Wiley ... n 1 p orbitals. These orbitals are of appropriate energy to form bonding interaction with ligand .... Image LFTi III .png center thumb 400px Ligand Field scheme summarizing bonding in the octahedral ... from the ligands one from each ligand form six symmetry adapted linear combinations SALCs of orbitals, also sometimes called ligand group orbitals LGOs . The irreducible representation s that these span ... of ligand SALC s with metal orbitals of the same symmetry. &pi bonding bonding in octahedral complexes occurs in two ways via any ligand p orbitals that are not being used in bonding, and via any or sup sup molecular orbitals present on the ligand. The p orbitals of the metal are used for bonding and are the wrong symmetry to overlap with the ligand p or or sup sup orbitals ... place. One important bonding in coordination complexes is metal to ligand bonding, also called Pi backbonding backbonding . It occurs when the LUMO s of the ligand are anti bonding sup sup ... from the metal d orbitals, sub O sub has increased and the bond between the ligand and the metal ... bond within the ligand weakens. The other form of coordination bonding is ligand to metal ... to the resulting symmetry bonding orbital between them and the metal. The metal ligand bond is somewhat ... ligand to metal bonding is not higher in energy than the anti bonding molecular orbital from the .... For that reason, sub O sub decreases when ligand to metal bonding occurs. The greater stabilisation that results from metal to ligand bonding is caused by the donation of negative charge away ... of ligand to metal bonding and metal to ligand bonding is a synergy synergic effect ... of the interaction between the ligand orbitals with the d orbitals on the central atom. As described ... more details
ligand, without the steric problems associated with TRANSPHOS. SPANphos is comparable to XANTPHOS but more reliably trans spanning. TRANSDIP, based on a cyclodextrin , is the first ligand to give ... Built Upon a Cyclodextrin Cavity is Transdip an Authentic Trans Spanning Ligand? journal Chemistry ... more details
orphan date May 2011 The Phage ligand technology is a technology to detect, bind and remove bacteria and bacterial toxin s by using highly specific bacteriophage derived proteins. ref http www.hyglos.de en technology technological background.html Technological background ref Origins The Bacteriophages Attachment and penetration host recognition of bacteriophages occur via bacteria binding proteins that have strong binding affinities to specific protein or carbohydrate structures on the surface of the bacterial host. At the end of the Bacteriophages Replication infection life cycle the bacteria lysing Endolysin is synthesized and degrades the bacterial peptidoglycan cell wall , resulting in lysis and therefore killing of the bacterial cell. Applications Bacteriophage derived proteins are used for detection and removal of bacteria ref Kretzer JW, Lehmann R, Banz M, Kim KP, Korn C. Loessner MJ 2007 Use of high affinity cell wall binding domains of bacteriophage endolysins for immobilization and separation of bacterial cells. Appl Environ Microbiol 73 1992 2000 ref ref Rozand, C., Feng, P. C. H. 2009 . Specifity analysis of a novel phage derived ligand in an Enzyme linked fluorescent assay for detection of Escherichia coli O157 H7. J. food protection 72, 1078 1081. ref and bacterial components especially Endotoxins Endotoxin contamination endotoxin contaminations in food, ref cite title Bacteriophages New Applications in Food Microbiology journal bioFood n 3 December 2006, page 2 url http www.biomerieux usa.com upload bioFood 20Dec 2006 1.pdf ref ref http www.hyglos.de en technology applications.html Applications of the phage ligand technology ref human diagnostics and decolonization of bacteria causing nosocomial infections e.g. MRSA . Protein modifications allow the biotechnological adaption to specific requirements. See also Affinity magnetic separation References references DEFAULTSORT Phage Ligand Technology Category Laboratory techniques Category Molecular biology ... more details
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