Catalytic Properties of Heterodinuclear GpdQ

It was shown in MCD measurements described in Sect. 3.2.2.2 that although a heterodinuclear Fe(II)Co(II) in GpdQ is formed upon the addition of Co(II) to the half-apo enzyme, it is not possible to generate a purely heterodinuclear derivative. Instead a mixture of Fe(II)Co(II) and homodinuclear Co(II)Co(II) centers is present. Addition of Co(II) to half-apo GpdQ is accompanied by an increase in catalytic activity as illustrated in Fig. 3.13, reaching a maximum value for k at of 0.7 at pH 11. For comparison, at the same pH the homodinuclear Co(II) derivative has a kcat of 1.6 s Taking into account that up to 40 % of the metal centers in the Fe(II)Co(II) derivatives are di-Co(II) the extrapolated activity of the heterodinuclear form alone is no larger than 0.1 s , only 5 % of that of its homodinuclear counterpart. 

3 Understanding the Overall Structure of GpdQ and Metal Binding 

In the next chapter the development and characterization of Zn(II) model complexes for this enzyme will be discussed. A thorough mechanistic and structural analysis of the biomimetics will be conducted. 

Schrddinger (2010) The PyMOL molecular graphics system. Version 1.3rl 

in Power Point Presentation, Research School of Chemistry, Australian National University, 2010 

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