Analyzing Post-Translational Modifications: Techniques and Challenges

This lecture discusses the analysis of post-translational modifications (PTMs) using mass spectrometry (MASSPEC). The instructor explains that PTMs are crucial as they affect various aspects of protein function, including activity and localization. The lecture highlights the versatility of MASSPEC in studying over 100 known protein modifications, emphasizing that some modifications can be combinatorial and interdependent. The instructor details how modifications impact the mass of peptides and their fragments in mass spectrometry, allowing for precise localization of modifications. The discussion extends to phosphoproteomics, focusing on the enrichment of phosphorylated peptides from the proteome. The instructor notes the challenges in phosphoproteomics, such as the need for efficient enrichment and the difficulty in pinpointing phosphorylation sites due to the presence of multiple serines, threonines, and tyrosines in peptides. The lecture concludes by addressing the complexities of interpreting the functional implications of identified modifications, underscoring the ongoing challenges in the field of proteomics.