Interprotein Electron Transfer in a Confined Space: Uncoupling Protein Dynamics from Electron Transfer by Sol-Gel Encapsulation
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- 作者：Judith M. Nocek ; Shelby L. Hatch ; Jennifer L. Seifert ; Gregory W. Hunter ; David D. Thomas ; and Brian M. Hoffman
- 刊名：Journal of the American Chemical Society
- 出版年：2002
- 出版时间：August 14, 2002
- 年：2002
- 卷：124
- 期：32
- 页码：9404 - 9411
- 全文大小：152K
- 年卷期：v.124,no.32(August 14, 2002)
- ISSN：1520-5126
文摘
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 becausethey represent a full range of affinities, are sensitive to different types of dynamic processes, and thus areexpected to respond differently to sol-gel encapsulation. The three systems are (i) the [Zn, Fe3+L] mixed-metal hemoglobin hybrids, where the 
rs/alpha.gif" BORDER=0>1-Zn and rs/beta2.gif" BORDER=0 ALIGN="middle">2-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 anintermediate 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 subunitrearrangements, 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 partnersencapsulated as a complex must stay together throughout a photoinitiated ET cycle, while proteinsencapsulated alone cannot acquire a partner. It further modulates intracomplex motions of the two partners.
rs/alpha.gif" BORDER=0>1-Zn and rs/beta2.gif" BORDER=0 ALIGN="middle">2-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 anintermediate 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 subunitrearrangements, 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 partnersencapsulated as a complex must stay together throughout a photoinitiated ET cycle, while proteinsencapsulated alone cannot acquire a partner. It further modulates intracomplex motions of the two partners.