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Published February 29, 1996 | public
Journal Article

Site-specific modification of α-helical peptides with electron donors and acceptors


We have prepared a histidine containing monomeric α-helical peptide, ETH6 (A_2KA_4KA_2HA_6HA_4KA_4K) in order to study long-range electron transfer (ET). This peptide was site-specifically labelled with a ruthenium (donor) at one histidine and a second ruthenium (acceptor) at a second histidine located on the same peptide. Both the unlabeled peptide and the singly labeled peptide-metal complex, Ru(bpy)_2(im)(His)-ETH6, were shown to form stable monomeric α-helical structures as determined by circular dichroism. Ru(NH_3)_4(py) was coupled to Ru(bpy_2)(im)(His)-ETH6, forming a Ru(bpy)_2(im)(His)-ETH6-(His)Ru(NH_3)_4(py) donor-acceptor complex. The synthesis and characterization of these peptides provide an entry into a series of molecules that are ideally suited to evaluate pathway differences such as H-bond mediated versus backbone-coupled long-range ET in protein α-helices.

Additional Information

© 1996 Elsevier Science S.A. Available online 15 January 1999. We thank H. Qian for the computer program implementing Lifson-Roig theory, O. Hathaway for mass spectral analysis and J.P. Kayyem for helpful discussions. SLM. acknowledges support from the Rita Allen Foundation, the David and Lucile Packard Foundation and the Searle Scholars Program. B.I.D. is partially supported by NIH Training Grant GM 08346. T.J.M. acknowledges support from the Petroleum Research Fund, American Chemical Society and the Research Corporation.

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