Ligands, terminology

Compared with the conventions adopted for discussing the relationship between drug concentration and response (Chapter 1), a rather different terminology has evolved for ligand-binding studies. 

The mathematical treatment of each of the fluorescence curves shown in O Figure 5-5 is identical. First nonspecific effects must be subtracted so that in each case we have a relationship between the concentration of ligand and the change in fluorescence. The binding equation is formally identical to the terminology for... 

Hogfeldt, E. Stability Constants of Metal-Ion Complexes. Part A Inorganic Ligands. lUPAC Chemical Data Series No. 22, Pergamon Press, New York (1982). McNaught, A. D. and Wilkinson, A. lUPAC Compendium of Chemical Terminology, Second Edition, Blackwell Science (1997). 

STEREOCHEMICAL TERMINOLOGY, lUPAC RECOMMENDATIONS Apical and equatorial ligand interchange, PSEUDOROTATION APICOPHILIOITY APOACTIVATOR Apolar side-chain interactions, HYDROPHOBIC EFFECT Apparent equilibrium constant,... 

The manifold intermediates in homogeneous transition-metal catalysis are certainly metal complexes and therefore show a behaviour like ordinary coordination compounds associations of phosphorus donors open up multifarious additional controls. Both, substrates and P ligands are Lewis bases that we have to consider and that compete at the coordination centers of the metal, leading to competitive, non-competitive or uncompetitive activation or inhibition processes in analogy to the terminology of enzyme chemistry... 

The first article in this volume, by Jenny P. dusker, treats general aspects of metal liganding to functional groups in proteins. This article presents a detailed summary of the geometry of interaction of metals with the various chemical groups of proteins. It also presents, in Sections I through VIII, a lucid development of the principles and terminology of the field of metal-protein interactions. It is with these sections that the newcomer to the field of metalloproteins should start. 

The molybdenum-acyl enolate 4 has been characterized spectroscopically by NMR and has been reported to exist as a single (observable) isomer88. Extended Hiickel calculations on model complexes suggest that a conformation similar to A is most favorable for enolates such as 488. The deprotonated di-hapto acyl ligand may also be described as a 2-(C,0)-ketene ligand both the ketene and enolate terminology appear in the literature. 

Five subtypes of muscarinic receptors have been identified, primarily on the basis of data from ligand-binding and cDNA-cloning experiments (see Chapters 6 and 7). A standard terminology (M4 through M5) for these subtypes is now in common use, and evidence — based mostly on selective agonists and antagonists—indicates that functional differences exist between several of these subtypes. 

If both Kaa and XBB are large enough, there will be no dissociation into monomers. The transition between conformation A and conformation B can occur cooperatively within the dimer or higher oligomer, and the mathematical relationships shown in Fig. 7-21 are still appropriate. One further restriction is needed to describe the MWC model. Only symmetric dimers are allowed. That is, Kaa and KBB KAB (see Eq. 7-31), and only those equilibria indicated with green arrows in Fig. 7-21 need be considered.30 In the absence of ligand X, the ratio [B2] / [A2] is a constant, 1 / L in the MWC terminology (Eq. 7-36 see also Eq. 7-31). 

We now examine what happens to the energy levels of a free-ion when it is subject to the effects of the surrounding ligands. The treatment will use the terminology of CFT for convenience. However, the results are presented in forms suitable for discussion in any form of LFT including the AOM. The discussion of the ligand field concept of effective operators operating on effective orbital sets as set out in Section 6.2.2.2 should be constantly kept in mind. 

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