Metal complexes interaction with biological

In this section we summarise the manner in which i -metals. Fig. 6, and where possible specifically the platinum complexes of concern here, interact with biological molecules. Some radio-tracer studies have been carried out on the distribution of platinum complexes in whole bacteria grown in media inocculated with the metal ion. The results are summarised in Table 11. It is noteworthy that the bacteriocidal complex [PtClg]2- was taken up almost entirely by the cytoplasmic protein whereas the filamentous forming neutral species, [Pt(NHs)2Cl4], was... 

Fig. 2.7. Characteristic rate constants (s 1) for substitution of inner-sphere H20 of various aqua ions. Note The substitution rates of water in complexes ML(H20)m will also depend on the symmetry of the complex (adapted from Frey, C.M. and Stuehr, J. (1974). Kinetics of metal ion interactions with nucleotides and base free phosphates in H. Sigel (ed.), Metal ions in biological systems (Vol. 1). Marcel Dekker, New York, p. 69).

One of the major ways in which metals interact with biological molecules is via complexation. The formation of metal complexes can be described by this simple equilibrium equation ... 

A complex set of interrelationships involving physical, chemical, biological, and pharmacological factors are involved when a metal ion interacts with a biological system. Therefore, it is more important to characterize the metal-biological system than to characterize the species in a simple chemical system. In a comprehensive work. Walker et al. (2003) reviewed approximately 100 diverse contributions dating from 1835 to 2003 to evaluate the relationships between about 20 physicochemical properties of cations and their potential to produce toxic effects in different organisms. 

Trefoil knots, and therefore the molecular knots discussed in this section, are chiral (Figure 4-29). The resolution of a dicopper(I) knot prepared from a helical precursor containing the 1,3-phenylene-linked bis-phenanthroline ligand described above (LI 198) has been achieved by crystallisation of the racemic cation with (5)-(+)-l,l -binaphthyl-2,2 -diyl phosphate [343]. As commented by these authors, the preparation of optically pure knot complexes is of great potential interest in relation both to interactions with biological molecules and, where the complexed metal has more than one accessible oxidation state, to enantioselective electron transfer [344]. 

In this section we outline briefly the spectral and magnetic properties of complexes of the metals of Table 5. These are the properties that enable the stereo-chemical and electronic structures of metal complexes to be determined in solution and, hence in a biological environment. A study of these properties will be necessary to understand the nature of the interaction of the anti-tumour compounds with biological systems. 

V. Interaction of Metal Complexes with Biological Ligands and Macro-molecules... 

An evaluation of the fate of trace metals in surface and sub-surface waters requires more detailed consideration of complexation, adsorption, coagulation, oxidation-reduction, and biological interactions. These processes can affect metals, solubility, toxicity, availability, physical transport, and corrosion potential. As a result of a need to describe the complex interactions involved in these situations, various models have been developed to address a number of specific situations. These are called equilibrium or speciation models because the user is provided (model output) with the distribution of various species. 

Electrostatically-controlled pre-association interactions have an important effect on rates for [Pd(dien)Cl]+ reacting with thione-containing nucleosides, nucleotides and oligonucleotides, as is often the case for reactions between metal complexes and this type of biological ligand. Interaction between the charged complex and the polyanionic oligonucleotide surface leads to an increase in both enthalpy and entropy of activation in the DNA or model environment (252). 

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