Nonionic, Cleavable Surfactant for Top-Down Proteomics

Nonionic surfactants are often used as general reagents
for cell
lysis enabling protein extraction, stabilization, and purification
under nondenaturing conditions for downstream analysis in structural
biology. However, the presence of surfactants in the sample matrix
often has a deleterious effect on electrospray ionization (ESI)-mass
spectrometry (MS) analysis of proteins and complexes. Here, we report
a nonionic, cleavable surfactant, n-decyl-disulfide-β-D-maltoside
(DSSM), for top-down proteomics. DSSM was designed to mimic the properties
of one of the most common surfactants used in structural biology,
n-dodecyl-β-D-maltoside (DDM), but contains a disulfide bond
that allows for facile cleavage and surfactant removal before or during
MS analysis. We have shown that DSSM is compatible with direct electrospray
ionization (ESI)-MS analysis and reversed-phase liquid chromatography
(RPLC)-MS analysis of proteins and protein complexes. We have demonstrated
that DSSM can facilitate top-down proteomic characterization of membrane
proteins such as a model ion channel protein and a G protein-coupled
receptor as well as endogenous proteins from cell lysates for the
determination of sequence variations and posttranslational modifications
(PTMs). Conceivably, DSSM could serve as a general replacement for
DDM in proteomic experiments and structural biology studies.