Metallo-protein complexes

In Table 10 there are some examples of EPR signals obtained from metallo-proteins. Most of this work has been conducted at low temperatures and it is now necessary to develop probes which contain metals and which will give signals at room temperature, e.g. d1 complexes. Such a label could be of use in many explorations of activity in biological systems. 

By use of appropriate sterically demanding carboxylates it is possible to generate four-, five-, and six-coordinated mononuclear iron(III) complexes. Ligand flexibility and electronic properties provide fine-tuning. These complexes are subunits of the models for di-iron(II) sites in metallo-proteins mentioned in the following section. 

A complexing agent should not be used in metallo-protein formulations, where the protein subunits are held by the metal.The EDTA, in rare instances, can increase the oxidation rate due to binding of the EDTA-metal complex to protein, resulting in site-specific generation of radicals. ... 

A fundamental understanding of oxidation-reduction reactions is vital to the inorganic chemist in contexts ranging from energy transduction - chemical to electrical and the converse, in technical matters in corrosion processes and metallurgy, redox processes in environmental chemistry and metalloenzymes and metallo-proteins involved in electron transfer. Electron-transfer reactions of transition metal complexes are accompanied by a change in the oxidation state of the metal... 

Complexes with pyrazole-based ligands are a frequent subject of chemical investigations aimed at understanding the relationship between the structure and activity of the active site of metallo-proteins. The metal ion in biological systems is often coordinated to one or more imidazole groups, which are part of histidine fragments of the proteins. A thermoanalytical and structural study of several copper complexes with pyrazole substitutes has been reported [156]. 

Schiff bases play an important role in coordination chemistry as they readily form stable complexes with most of the transition metals. The development of bioinorganic chemistry has increased interest in Schiff base complexes as it has been recognised that many of these complexes may serve as models for the metal-containing sites in metallo-proteins and -enzymes. Schiff also discovered the experimental technique of preparing... 

It is to be expected then that metallo-proteins will form dioxygen complexes of great diversity. For example, those containing the same metal ion such as the ferrous-containing dioxygenases will not automatically share the same mechanisms of catalysis. 

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