add SDS-PAGEgel assays

assays/SDS-PAGEgel/README.md

+<img src=dataset\FigS1C.jpg width=60%>
+
+### Supplementary Figure 1 C) caption
+
+**Supplementary Figure 1 C).**  Separation
+of pull-down samples on SDS-PAGE gel prior to submission for mass spectroscopy. Pull-down was performed with untreated laminarin, biotinylated laminarin and
+biotinylated elf18 at two different pH values. Areas indicated by dotted lines were excised from the gel and further processed for mass spectrometric analyses. Elf18,
+peptide from bacterial elongation factor Tu; ROS, reactive oxygen species; RLU, relative luminescence units.
+
+### Supplementary Figure 1 C) source
+https://www.cell.com/current-biology/pdfExtended/S0960-9822(23)01449-5
\ No newline at end of file