Interprotein electron transfer in a confined space: Uncoupling protein dynamics from electron transfer by sol-gel encapsulation

Judith M. Nocek, Shelby L. Hatch, Jennifer L. Seifert, Gregory W. Hunter, David D. Thomas, Brian M. Hoffman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

In this paper, we describe the first observations of photoinitiated interprotein electron transfer (ET) within sol-gels. We have encapsulated three protein-protein complexes, specifically selected because they represent a full range of affinities, are sensitive to different types of dynamic processes, and thus are expected to respond differently to sol-gel encapsulation. The three systems are (i) the [Zn, Fe3+L] mixed-metal hemoglobin hybrids, where the α1-Zn and β2-Fe subunits correspond to a "predocked" protein-protein complex with a crystallographically defined interface (Natan, M. J.; Baxter, W. W.; Kuila, D.; Gingrich, D. J.; Martin, G. S.; Hoffman, B. M. Adv. Chem. Ser. 1991, 228 (Electron-Transfer Inorg., Org., Biol. Syst.), 201-213), (ii) the Zn-cytochrome c peroxidase complex with cytochrome c, [ZnCcP, Fe3+Cc], having an intermediate affinity between its partners (Nocek, J. M.; Zhou, J. S.; De Forest, S.; Priyadarshy, S.; Beratan, D. N.; Onuchic, J. N.; Hoffman, B. M. Chem. Rev. 1996, 96, 2459-2489), and (iii) the [Zn-deuteromyoglobin, ferricytochrome b5] complex, [ZnDMb, Fe3+b5], which is loosely bound and highly dynamic (Liang, Z.-X.; Nocek, J.; Huang, K.; Hayes, R. T.; Kurnikov, I. V.; Beratan, D. N.; Hoffman, B. M. J. Am. Chem. Soc. 2002, 124, 6849-6859. Intersubunit ET within the hybrid does not involve second-order processes or subunit rearrangements, and thus is influenced only by perturbations of high-frequency motions coupled to ET. For the latter two complexes, sol-gel encapsulation eliminates second-order processes: protein partners encapsulated as a complex must stay together throughout a photoinitiated ET cycle, while proteins encapsulated alone cannot acquire a partner. It further modulates intracomplex motions of the two partners.

Original languageEnglish (US)
Pages (from-to)9404-9411
Number of pages8
JournalJournal of the American Chemical Society
Volume124
Issue number32
DOIs
StatePublished - Aug 14 2002

ASJC Scopus subject areas

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

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