Application of Mass-Spectrometry Compatible Photocleavable Surfactant for Next-Generation Proteomics Using Rice Leaves

The solubilization of isolated proteins into the adequate buffer containing of surfactants is primary step for proteomic analysis. Particularly, sodium dodecyl sulfate (SDS) is the most widely used surfactant, however, it is not compatible with mass spectrometry (MS). Therefore, it must be removed prior to MS analysis through rigorous washing, which eventually results in inevitable protein loss. Recently, photocleavable surfactant, 4-hexylphenylazosulfonate (Azo), was reported which can be easily degraded by UV irradiation and is compatible with MS during proteomic approach using animal tissues. In this study, we employed comparative label-free proteomic analysis for evaluating the solubilization efficacies of the Azo and SDS surfactants using rice leave proteins. This approach led to identification of 3,365 proteins of which 682 proteins were determined as significantly modulated. Further, according to the subcellular localization prediction in SDS and Azo, proteins localized in the chloroplast were the major organelle accounting for 64% of the total organelle in the SDS sample, while only 37.5% of organelle proteins solubilized in the Azo were predicted to be localized in chloroplast. Taken together, this study validates the efficient solubilization of total protein isolated from plant material for bottom-up proteomics. Azo surfactant is suitable as substitute of SDS and promising for bottom-up proteomics as it facilitates robust protein extraction, rapid washing step during enzymatic digestion, and MS analysis.