Cobalt cage complexes as mediators of protein electron transfer

He, Felix M. C. and Bernhardt, Paul V. (2016) Cobalt cage complexes as mediators of protein electron transfer. Journal of Biological Inorganic Chemistry, 22 5: 1-14. doi:10.1007/s00775-016-1427-y


Author He, Felix M. C.
Bernhardt, Paul V.
Title Cobalt cage complexes as mediators of protein electron transfer
Journal name Journal of Biological Inorganic Chemistry   Check publisher's open access policy
ISSN 1432-1327
0949-8257
Publication date 2016-12-28
Sub-type Article (original research)
DOI 10.1007/s00775-016-1427-y
Open Access Status Not yet assessed
Volume 22
Issue 5
Start page 1
End page 14
Total pages 14
Place of publication Heidelberg, Germany
Publisher Springer
Language eng
Abstract A selection of cobalt (III)/(II) macrobicyclic 'sarcophagine' (sar) cage complexes with N3S3 mixed donor sets but differing in a single apical substituent has been chosen to span a redox potential range of +150 to -150 mV vs the normal hydrogen electrode and thus acts as redox buffers in protein spectroelectrochemistry and redox potentiometry. The cobalt(III) cage complexes are all based on the same parent structure [Co(XMeN3S3sar)](3+), where X, the variable apical substituent, is -NO2, -Cl, -OH, -NH2, or -NMe 3(+) , and a methyl group occupies the opposite apical position. The X-ray crystal structures of selected members of this series are reported. Changes to the apical substituent X enable the Co(III/II) redox potential to be tuned across a range of more than 200 mV by the inductive effects of the functional group. The pH dependence of the redox potential enabled the pK a values of some functional groups to be determined. The complexes were successfully employed as electron transfer mediators in the spectroelectrochemical investigation of a variety of heme proteins.
Formatted abstract
A selection of cobalt (III)/(II) macrobicyclic ‘sarcophagine’ (sar) cage complexes with N3S3 mixed donor sets but differing in a single apical substituent has been chosen to span a redox potential range of +150 to −150 mV vs the normal hydrogen electrode and thus acts as redox buffers in protein spectroelectrochemistry and redox potentiometry. The cobalt(III) cage complexes are all based on the same parent structure [Co(XMeN3S3sar)]3+, where X, the variable apical substituent, is –NO2, –Cl, –OH, –NH2, or –NMe3+, and a methyl group occupies the opposite apical position. The X-ray crystal structures of selected members of this series are reported. Changes to the apical substituent X enable the CoIII/II redox potential to be tuned across a range of more than 200 mV by the inductive effects of the functional group. The pH dependence of the redox potential enabled the pKa values of some functional groups to be determined. The complexes were successfully employed as electron transfer mediators in the spectroelectrochemical investigation of a variety of heme proteins.
Keyword Protein
Spectroelectrochemistry
Voltammetry
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
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