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Molecules 2018, 23(11), 2900; https://doi.org/10.3390/molecules23112900

Site-Specific Labeling of Proteins with Near-IR Heptamethine Cyanine Dyes

Department of Chemistry, Texas A & M University, Box 30012, College Station, TX 77842, USA
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Author to whom correspondence should be addressed.
Academic Editor: Maged Henary
Received: 19 October 2018 / Revised: 5 November 2018 / Accepted: 6 November 2018 / Published: 7 November 2018
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Abstract

Convenient labeling of proteins is important for observing its function under physiological conditions. In tissues particularly, heptamethine cyanine dyes (Cy-7) are valuable because they absorb in the near-infrared (NIR) region (750–900 nm) where light penetration is maximal. In this work, we found Cy-7 dyes with a meso-Cl functionality covalently binding to proteins with free Cys residues under physiological conditions (aqueous environments, at near neutral pH, and 37 °C). It transpired that the meso-Cl of the dye was displaced by free thiols in protein, while nucleophilic side-chains from amino acids like Tyr, Lys, and Ser did not react. This finding shows a new possibility for convenient and selective labeling of proteins with NIR fluorescent probes. View Full-Text
Keywords: heptamethine cyanine; protein labeling; thiol labeling; cancer targeting; vimentin heptamethine cyanine; protein labeling; thiol labeling; cancer targeting; vimentin
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Lin, C.-M.; Usama, S.M.; Burgess, K. Site-Specific Labeling of Proteins with Near-IR Heptamethine Cyanine Dyes. Molecules 2018, 23, 2900.

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