The tape-stripping procedure for the identification of protein N-termini within skin specimens

Minimal invasive sampling techniques are an essential tool for all types of biological analyses. For the biopsy of the skin, the tape-stripping procedure has been established as a reasonable technique to sample the stratum corneum, the outermost section of the epidermis. Tape strips are polymer-based adhesive sheets, which are iteratively applied to the volunteer"s skin in order to remove layers of extracellular matrix and embedded cells.

While the technique has many benefits, it provides certain analytical challenges, especially for protein-centered approaches. Extraction of the proteins requires to overcome non-covalent interactions with the adhesive, and highly cornified cells need to be lysed. We previously established a protocol, which utilized detergent‑based buffers in combination with the SP3 protocol [1] to tackle this task and enabled the identification of hundreds of proteins from single strips [2].

We now expanded the analytics of tape-stripped specimens with the application of an N-terminomics strategy. For this, we combined our established procedure with the high-efficiency undecanal-based N-termini enrichment (HUNTER) protocol [3], and analyzed isolated protein N-termini by LC-MS methods. The technique enables the characterization of hundreds of termini from limited sample material and indicates a comprehensive processing of proteins within the stratum corneum.

[1] Hughes, C.S., Moggridge, S., Müller, T., Sorensen, P.H., et al., Nat Protoc 2019, 14, 68.

[2] Kaleja, P., Emmert, H., Gerstel, U., Weidinger, S., Tholey, A., Journal of Proteomics 2020, 217, 103678.

[3] Weng, S.S.H., Demir, F., Ergin, E.K., Dirnberger, S., et al., Molecular & Cellular Proteomics 2019, 18, 2335.