Ulrich Arnold

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Materials. Chemicals were of commercial reagent grade or better, and were used without further purification. Instruments. Peptides were synthesized with an Applied Biosystems Pioneer synthesizer at the University of Wisconsin Biotechnology Center. Mass spectra were obtained with Perkin Elmer Sciex API 365 electrospray ionization (ESI) and Bruker Biflex III(More)
The introduction of non-natural amino acid residues or modules into proteins provides a new means to explore the basis for conformational stability, folding/unfolding behavior, or biological function. We exploited intein-mediated protein ligation to produce a semisynthetic ribonuclease A. Of the 124 residues of RNase A, residues 1-94 were linked to an(More)
Nonnatural residues can endow proteins with desirable properties. Here, replacing a proline residue that has a cis peptide bond in native ribonuclease A with 5,5-dimethyl-l-proline is shown to accelerate protein folding by 6-fold and enhance conformational stability by DeltaTm = 2.8 +/- 0.3 degrees C while having no effect on enzymatic activity. The(More)
A long-term goal of biological chemists is to create new proteins with desirable properties. 1 One potentially fruitful approach is to remodel the frameworks designed by nature. 2 The genetic code limits the components of natural proteins to 20 or so R-amino acids. Methods that overcome this limitation but still rely on the ribosome are similarly limited to(More)
Proline is unique among the natural amino acids in the similar propensity of its peptide bond to be in the cis or trans conformation. 1 This attribute affects many processes, including the rate at which proteins fold, 2 their structures, 3 and their activities. 4 Other aliphatic amino acids can serve as mimics for proline residues with trans-peptide bonds.(More)
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)(More)
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