Oxidative Folding of Peptides with Cystine-Knot Architectures: Kinetic Studies and Optimization of Folding Conditions

Authors

  • Michael Reinwarth,

    1. Institute for Organic Chemistry and Biochemistry, Technische Universität Darmstadt, Petersenstr. 22, 64287 Darmstadt (Germany)
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  • Bernhard Glotzbach,

    1. Institute for Organic Chemistry and Biochemistry, Technische Universität Darmstadt, Petersenstr. 22, 64287 Darmstadt (Germany)
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  • Michael Tomaszowski,

    1. Institute for Organic Chemistry and Biochemistry, Technische Universität Darmstadt, Petersenstr. 22, 64287 Darmstadt (Germany)
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  • Sebastian Fabritz,

    1. Institute for Organic Chemistry and Biochemistry, Technische Universität Darmstadt, Petersenstr. 22, 64287 Darmstadt (Germany)
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  • Dr. Olga Avrutina,

    Corresponding author
    1. Institute for Organic Chemistry and Biochemistry, Technische Universität Darmstadt, Petersenstr. 22, 64287 Darmstadt (Germany)
    • Institute for Organic Chemistry and Biochemistry, Technische Universität Darmstadt, Petersenstr. 22, 64287 Darmstadt (Germany)
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  • Prof. Dr. Harald Kolmar

    Corresponding author
    1. Institute for Organic Chemistry and Biochemistry, Technische Universität Darmstadt, Petersenstr. 22, 64287 Darmstadt (Germany)
    • Institute for Organic Chemistry and Biochemistry, Technische Universität Darmstadt, Petersenstr. 22, 64287 Darmstadt (Germany)
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Abstract

Bioactive peptides often contain several disulfide bonds that provide the main contribution to conformational rigidity and structural, thermal, or biological stability. Among them, cystine-knot peptides—commonly named “knottins”—make up a subclass with several thousand natural members. Hence, they are considered promising frameworks for peptide-based pharmaceuticals. Although cystine-knot peptides are available through chemical and recombinant synthetic routes, oxidative folding to afford the bioactive isomers still remains a crucial step. We therefore investigated the oxidative folding of ten protease-inhibiting peptides from two knottin families, as well as that of an HIV entry inhibitor and of aprotinin, under two conventional sets of folding conditions and by a newly developed procedure. Kinetic studies identified folding conditions that resulted in correctly folded miniproteins with high rates of conversion even for highly hydrophobic and aggregation-prone peptides in concentrated solutions.

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