De novo design, synthesis, and characterization of quinoproteins

Li, Wen-Wu; Hellwig, Petra; Ritter, Michaela; Haehnel, Wolfgang

Abstract

Quinones and quinoproteins are essential redox components and enzymes in biological systems. Here, we report the de novo design, synthesis, and properties of model four-α-helix bundle quinoproteins. The proteins were designed and constructed from three different helices with 21 or 22 amino acid residues by chemoselective ligation to a cyclic decapeptide template. A free cysteine unit is placed at the hydrophobic core of the protein for binding of ubiquinone-0 and menaquinone-0 through a thioether bond. The quinoproteins with molecular weights of 11–12 kDa were characterized by electrospray ionization mass spectrometry, UV/Vis spectroscopy, size-exclusion chromatography, circular dichroism measurements, 1H NMR spectroscopy, cyclic voltammetry, and redox-induced FTIR difference spectroscopy. The midpoint redox potentials at pH 8 in aqueous solution Em,8 of thioether conjugates with N-acetyl cysteine methyl ester were 89 mV and −63 mV and with a synthetic protein 229 mV and 249 mV versus standard hydrogen electrode (SHE) for ubiquinone-0 and menaquinone-0, respectively. Detailed redox-induced FTIR difference spectroscopic studies of the model compounds and quinoproteins show the special resonance features for CO bands at 1656–1660 and 1655–1665 cm−1 due to the sulfur substitution to ubiquinone-0 and menaquinone-0, respectively. The construction of model quinoproteins represents a significant step toward more complex artificial redox systems.

Citation

Li, W., Hellwig, P., Ritter, M., & Haehnel, W. (2006). De novo design, synthesis, and characterization of quinoproteins. Chemistry - A European Journal, 12(27), 7236-7245. https://doi.org/10.1002/chem.200501212

• Journal Article Type: Article
• Publication Date: Sep 18, 2006
• Deposit Date: Oct 5, 2023
• Journal: CHEMISTRY-A EUROPEAN JOURNAL
• Print ISSN: 0947-6539
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 12
• Issue: 27
• Pages: 7236-7245
• DOI: https://doi.org/10.1002/chem.200501212