Relative Quantification of Palmitoyl Peptides using Hydrophobic Alkyl Tags

摘要

S-palmitoylation is the post-translational covalent attachment of a palmitate to cysteine residues. Relative quantification of palmitoyl peptides to their unmodified counterparts by LC-MS is challenging because the thioester linkage is labile and palmitoyl group losses could occur during sample preparation if care is not taken. In addition, palmitoylation dramatically increases the hydrophobicity of peptides, which makes it difficult to analyze palmitoylated and unmodified peptides in a single HPLC run. Here, we present an optimized sample preparation procedure that preserves palmitoyl groups for direct MS analysis, and a derivatization strategy that enables relative LC-MS quantification of palmitoyl and unmodified peptides using hydrophobic alkyl tags.