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Ethylenediamine ligand chelating to a metal with two bonds Cu 2+ complexes with nonchelating methylamine (left) and chelating ethylenediamine (right) ligands. The chelate effect is the greater affinity of chelating ligands for a metal ion than that of similar nonchelating (monodentate) ligands for the same metal.
This ligand–metal–ligand geometric parameter is used to classify chelating ligands, including those in organometallic complexes. It is most often discussed in terms of catalysis , as changes in bite angle can affect not just the activity and selectivity of a catalytic reaction but even allow alternative reaction pathways to become accessible.
Systematic evolution of ligands by exponential enrichment (SELEX), also referred to as in vitro selection or in vitro evolution, is a combinatorial chemistry technique in molecular biology for producing oligonucleotides of either single-stranded DNA or RNA that specifically bind to a target ligand or ligands.
The chelate effect increases as the number of chelate rings increases. For example, the complex [Ni(dien) 2)] 2+ is more stable than the complex [Ni(en) 3)] 2+; both complexes are octahedral with six nitrogen atoms around the nickel ion, but dien (diethylenetriamine, 1,4,7-triazaheptane) is a tridentate ligand and en is bidentate. The number of ...
For example, ferrocene, [(η 5-C 5 H 5) 2 Fe], has two cyclopentadienyl ligands giving a hapticity of 5, where all five carbon atoms of the C 5 H 5 ligand bond equally and contribute one electron to the iron center. Ligands that bind non-contiguous atoms are denoted the Greek letter kappa, κ. [7] Chelating κ2-acetate is an example.
For example, in the context of protein function, the binding of calcium to troponin in muscle cells can induce a conformational change in troponin. This allows for tropomyosin to expose the actin-myosin binding site to which the myosin head binds to form a cross-bridge and induce a muscle contraction .
DOTA is derived from the macrocycle known as cyclen.The four secondary amine groups are modified by replacement of the N-H centers with N-CH 2 CO 2 H groups. The resulting aminopolycarboxylic acid, upon ionization of the carboxylic acid groups, is a high affinity chelating agent for di- and trivalent cations.
EcoRI for example generates an AATT end, and since A and T have lower melting temperature than C and G, its melting temperature T m is low at around 6 ° C. [21] For most restriction enzymes, the overhangs generated have a T m that is around 15 ° C. [20] For practical purposes, sticky end ligations are performed at 12-16 ° C, or at room ...