Fig. 8: Analysis of rBPSL1038 conformation in various salt concentration.

a Size exclusion chromatography (SEC) analysis of rBPSL1038 in buffer containing 0, 25, 50, 100 and 250 mM of NaCl using HiLoad 16/600 Superdex 75 pg column (Cytiva, USA). X-axis represents the retention volume of the SEC. Represented by the estimated molecular weight, the profile shows that rBPSL1038 protein undergoes conformational changes as the NaCl concentration increases. The rBPSL1038 appears as a monomeric protein (11 kDa) in 250 mM of NaCl but forms a dimer (~28 kDa) and oligomeric proteins (32, 35 and 52 kDa) with the reduction of salt concentrations. b Dynamic scattering analysis of rBPSL1038 size distribution in SEC buffer (25 mM Tris pH 7.5 containing 0, 25, 50, 100 and 250 mM NaCl). The diameter of all the BPSL1038 samples was measured by Zetasizer Nano Series (Malvern Panalytical, UK) with an average diameter of 5.6 nm (range of 4.8–6.5 nm), indicating that the size of the rBPSL1038 (~27–37 kD) remains similar in various salt concentrations, suggesting that the observation of NaCl concentration-related SEC profiles could be an artefact.