Protein prosthesis: β‐peptides as reverse‐turn surrogates |
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Authors: | Ulrich Arnold Bayard R Huck Samuel H Gellman Ronald T Raines |
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Institution: | 1. Institute of Biochemistry and Biotechnology, Martin‐Luther University Halle‐Wittenberg, 06120 Halle, Germany;2. Department of Biochemistry, University of Wisconsin‐Madison, Madison, Wisconsin 53706;3. Department of Chemistry, University of Wisconsin‐Madison, Madison, Wisconsin 53706 |
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Abstract: | The introduction of non‐natural modules could provide unprecedented control over folding/unfolding behavior, conformational stability, and biological function of proteins. Success requires the interrogation of candidate modules in natural contexts. Here, expressed protein ligation is used to replace a reverse turn in bovine pancreatic ribonuclease (RNase A) with a synthetic β‐dipeptide: β2‐homoalanine–β3‐homoalanine. This segment is known to adopt an unnatural reverse‐turn conformation that contains a 10‐membered ring hydrogen bond, but one with a donor–acceptor pattern opposite to that in the 10‐membered rings of natural reverse turns. The RNase A variant has intact enzymatic activity, but unfolds more quickly and has diminished conformational stability relative to native RNase A. These data indicate that hydrogen‐bonding pattern merits careful consideration in the selection of beneficial reverse‐turn surrogates. |
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Keywords: | conformational stability expressed protein ligation foldamer β ‐peptide reverse turn ribonuclease A |
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