Interaction of ligands

Synthesis of chelates (including those with heterocyclic ligands) by direct interaction of ligands with metals or metal oxides, particularly using electrochemical or tribochemical activation 97MI41. 

There is a single assumption in these measurements--namely that the antibody only quenches free ligand. This has been demonstrated specifically by flow cytometry in experiments which show that there is no quenching of ligand on the cell (3). The kinetic analysis depends on rapid interaction of ligand and antibody, which in these experiments is essentially within the mixing time. 

Color changes often provide evidence for the interaction of ligands and metal cations, particularly for the transition metals. The Ni + cation provides an example. Figure 20-5 shows that nickel(It) sulfate, a white crystalline solid, dissolves in water to give a green solution. The green color cannot be due to Ni or S04 , which the white solid shows to be colorless. Rather, the color comes from the octahedral complex that forms when each nickel ion binds to six water molecules NiS04(. ) -I- 6H2 0(/) [Ni (H2 0)g] (ag) + SOY (gg)... 

Blume A. Interaction of ligands with the opiate receptors of brain membranes regulation by ions and nucleotides. Proc Natl Acad Sci USA 1978 ... 

Both the onset of binding, when the radioligand is first applied, and offset, when dissociation is promoted, can be studied directly. The relevant kinetic equations relating to the simple bimolecular interaction of ligand with receptor are presented in Chapter 1, Section 1.3. 

The interaction of ligands derived from salicylic acid and its derivatives has been extensively investigated (83, 147, 149, 160, 170, 176, 183-205). A similar situation obtains with regard to l-hydroxy-2-naphthoic acid (185, 194, 196, 198, 206-215). Salicylic acid derivatives may be useful in chelation therapy for beryllium poisoning (2). 

In general, there are three types of interactions of ligands with bare metal clusters. 

In addition to being used for structural determinations of protein targets, NMR is increasingly being used to examine the dynamic interactions of ligand-receptor binding. Two NMR properties are particularly important chemical shift and nuclear spin relaxation. 

The above discussion provides only a brief overview of how fluorescence techniques can be used to study the interactions of ligands with their receptors. We have focused on the quantitation of the binding parameters and compared the data with that which may be obtained with those from radiolabelled ligand binding studies. The number of applications of fluorescence in the study of neurochemistry and molecular biology is ever increasing. Outside the scope of this review is, for example, the use of fluorescence microscopy to monitor cell surface expression and targeting of receptors or the use of fluorescence probes to monitor ion transport into and out of cells. 

The maximum value of ki is limited by the diffusion-controlled rate for collision between two molecules. For a small molecule binding to a macromolecular receptor, this rate is of the order of 10 to 10 M -s If the rates deviate from this markedly it suggests that the interaction of ligand with receptor is more complex. 

If dissociation does not occur mono-exponentially, it may indicate that there are multiple ligand-receptor complexes or that the mechanism of interaction of ligand with receptor is more complex. 

Ozenberger BA, Young KH. 1995. Functional interaction of ligands and receptors of the hematopoietic superfamily in yeast. Mol Endocrinol 9 1321-1329. 

Table 8.2 Rate Constants (kf) for Interaction of Ligands (L) with V(H20)j+ at 25°C ...

Chemical interactions of ligands with these receptors may involve the formation of many types of bonds, including ionic, hydrogen, van der Waals , and covalent Ligand-receptor interactions are often stereospecific (i.e., one stereoisomer is usually more potent than the other)... 

Unstable Systems Formed by the Interaction of Ligands with Metal Ions in Stable States of Oxidation. 

Figure 16. Principal axes for hyperfine interaction of ligand atom.

A study of the interaction of ligand (88) with alkali metal complexes has been reported.423 The NaNCS complex contains the ligand bound to the Na+ by five oxygen donors but the sulfur does hot interact at all the six coordination of the cation is completed by the NCS- anion.424 The KNCS complex has the metal at the centre of a hexagon of donors, all of interact with the metal, 2S and in the RbNCS complex the Rb+ sits out of the plane towards an N-bonded NCS- anion and is also coordinated by a sulfur from an adjacent ring to give a dimeric structure.426... 

The N,P,0-ligand depicted in 338 in the N,P-chelate unit follows from L(x 4-cod)Pd(Cl)MeJ (04JCS(D)3251). With silver tetrafluoroborate in acetonitrile/methylene chloride, cationic 339 follows, which under carbon monoxide is transformed to acetylated 340. The product of interaction of ligand 341 with [(T)3-C3H5)Pd(Cl)]2 is an efficient catalyst of asymmetric allylic substitutions (04JOC5060). 

---