Nanosensor Detection of an Immunoregulatory Tryptophan Influx/Kynurenine Efflux Cycle
Figure 5
Imaging of Tryptophan-Kynurenine Exchange with FLIPW-CTYT in COS-7 Cells
(A) Molecular structures of l-tryptophan, 3-hydroxy-l-kynurenine, and 3-hydroxy-anthranilic acid. (B) Perfusion of COS-7 cells with 100 μM l-tryptophan (L-Trp), 100 μM l-histidine (L-His), and 200–1,000 μM 3-hydroxy-dl-kynurenine (DL-HK) in Tyrode's buffer. According to the FRET theory, an increase in Venus signal is accompanied by a decrease in eCFP signal. Ratio defined as fluorescence intensity quotient obtained with emission filters 535/40 nm over 480/30 nm.