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. 2019 Feb 5;8:e43230. doi: 10.7554/eLife.43230

Figure 1. Design and synthesis of clickable and photoswitchable ceramides.

(a) Chemical structure of C16:0-Cer, with color-coded sphingoid base (black) and N-acyl chain (red). (b) Chemical structures of clickable and photoswitchable ceramides caCer-1–4. (c) Chemical structures of clickable ceramide cCer and photoswitchable ceramide ACe-1. (d) caCer-1 undergoes reversible isomerization between its cis- and trans-configuration with UV-A (365 nm) and blue (470 nm) light, respectively. (e) Chemical synthesis of the photoswitchable sphingoid base aSph-1, which was N-acylated with a terminal alkyne-functionalized C15 fatty acid to afford caCer-3. (f) UV-Vis spectra of the red-shifted variant caCer-3 (50 μM in DMSO) in its dark-adapted (trans, black), UV-A-irradiated (cis, violet) and blue-irradiated (trans, blue) states. (g) caCer-3 (50 μM in DMSO) undergoes isomerization to its cis-configuration with UV-A light (350–390 nm), and this effect is completely reversed with blue light (465 nm). Photoswitching was monitored by measuring the absorbance at 365 nm.

Figure 1.

Figure 1—figure supplement 1. Chemical synthesis of caCer-1.

Figure 1—figure supplement 1.

The photoswitchable and clickable fatty acid cFAAzo-4 was synthesized and then coupled to d-erythro-sphingosine to afford caCer-1 in good yield.
Figure 1—figure supplement 2. Chemical synthesis of caCer-2.

Figure 1—figure supplement 2.

The photoswitchable and clickable fatty acid cFAAzo-1 was synthesized from known alkyne 3. cFAAzo-1 was then coupled to d-erythro-sphingosine to afford caCer-2 in good yield.
Figure 1—figure supplement 3. UV-Vis spectra of caCer-1, caCer-2 and Cer-4.

Figure 1—figure supplement 3.

UV-Vis spectra of (a) caCer-1, (b) caCer-2 and (c) caCer-4 (50 μM in DMSO) in their dark-adapted (trans, black), UV-A-irradiated (cis, violet) and blue-irradiated (trans, blue) states.
Figure 1—figure supplement 4. Chemical synthesis of caCer-4.

Figure 1—figure supplement 4.

(a) Chemical synthesis of a terminal alkyne-functionalized C15 fatty acid. (b) Chemical synthesis of the photoswitchable sphingoid base aSph-2, which was N-acylated with a terminal alkyne-functionalized C15 fatty acid to afford caCer-4.