Artificial Metalloproteins Containing Co4O4 Cubane Active Sites

Lisa Olshansky, Raúl Huerta-Lavorie, Andy I. Nguyen, Jaicy Vallapurackal, Ariel Furst, T. Don Tilley, A. S. Borovik

Research output: Contribution to journalArticlepeer-review

Abstract

Artificial metalloproteins (ArMs) containing Co4O4 cubane active sites were constructed via biotin-streptavidin technology. Stabilized by hydrogen bonds (H-bonds), terminal and cofacial CoIII-OH2 moieties are observed crystallographically in a series of immobilized cubane sites. Solution electrochemistry provided correlations of oxidation potential and pH. For variants containing Ser and Phe adjacent to the metallocofactor, 1e-/1H+ chemistry predominates until pH 8, above which the oxidation becomes pH-independent. Installation of Tyr proximal to the Co4O4 active site provided a single H-bond to one of a set of cofacial CoIII-OH2 groups. With this variant, multi-e-/multi-H+ chemistry is observed, along with a change in mechanism at pH 9.5 that is consistent with Tyr deprotonation. With structural similarities to both the oxygen-evolving complex of photosystem II (H-bonded Tyr) and to thin film water oxidation catalysts (Co4O4 core), these findings bridge synthetic and biological systems for water oxidation, highlighting the importance of secondary sphere interactions in mediating multi-e-/multi-H+ reactivity.

Original languageEnglish (US)
Pages (from-to)2739-2742
Number of pages4
JournalJournal of the American Chemical Society
Volume140
Issue number8
DOIs
StatePublished - Feb 28 2018
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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