Figure 2.
Peptide specific for claudin-1. (A) The extracellular loop of CLDN1, consisting of amino acids 53–80 (red), was used to select the (B) peptide with sequence RTSPSSR. The chemical structure of the peptide (black) with a GGGSK linker (blue) and Cy5.5 label (red) is shown. (C) Scrambled peptide with sequence SPTSSRR labeled with Cy5.5 is used as control. (D) Fluorescence spectra with λex = 671-nm excitation shows peak emission in near-infrared at 710 nm for both peptides. (E) For RTS*-Cy5.5, the mass-to-charge (m/z) ratio of 1740.9 was measured on mass spectrometry, which agrees with the expected value.