Biology subjects

von Stetten, F.

Publications and source records attributed to von Stetten, F..

3 recordsLinked to original sources

bioRxiv2026

Sample preparation for direct nanopore based protein identification via tryptic peptide recognition

Rapid, cost-efficient and miniaturized protein analysis is essential for point-of-care clinical diagnostics. Nanopores offer a promising alternative to mass spectrometry, offering high-resolution, single-molecule sensing with a minimal footprint. However, peptide-level protein identification remains challenging due to difficulties in assigning nanopore signals to peptide sequences and the incompatibility of conventional proteolysis workflows with nanopore sensing. Here we integrate a single-pot, solid-phase-enhanced sample preparation (SP3) workflow with nanopore sensing. The SP3 protocol decouples proteolysis from interfering components via magnetic bead cleanup, yielding a digest compatible with nanopore sensing. As a proof of concept, tryptic digests of myelin basic protein measured with an engineered aerolysin variant (AeL-R220S) generated a reproducible five-peak peptide fingerprint. Cross-validation against a synthetic peptide library and LC-MS/MS enabled reference-based assignment of blockade signatures to four MBP-derived peptides. This approach establishes SP3 as a sample-preparation workflow for nanopore sensing, paving the way for label-free identification and characterization of protein targets.

biochemistry↗

bioRxiv2024

Lossless Single-Molecule Counting To Absolute QuantifyProteoforms

A novel immunoassay, termed Protein Interaction Coupling (PICO), is introduced to deliver unequivocal, reference-free quantification of proteoforms - absolute quantification. PICO employs a compartmentalized, homogeneous single-molecule assay with a lossless and highly sensitive signal generation, capable of detecting down to a few molecules per reaction. Additionally, it utilises a background-free, digital enumeration principle, known as the decouplexing. PICO is presented as exact mathematical theories, providing a theoretical comprehension of its chemistry. Consequently, PICO demonstrates absolute quantification, as exemplified with recombinant and non-recombinant ErbB2 and multi-tagged peptide rTRX targets, validating absolute quantification against internal and external references in both analytical and cellular matrices. Furthermore, PICO enables combinatorial multiplexing (cplex), a readout between any two antibodies, demonstrated by an 8-plex antibody, 12-cplex PICO, measuring functional changes of ErbB pathway upon mock and dactolisib treatment delivering absolute quantitative cellular stoichiometry. PICO possesses immense potential for versatile, standardized, and accurate protein measurements, offering insights into physiological and perturbed cellular processes.

molecular biology↗

bioRxiv2022

Integrated workflow of down-scaled Smart-seq2 and absolute quantitative, single-cell digital PCR validates lack of representability of low-abundant transcripts

Single-cell RNA sequencing (scRNA-seq) can unmask transcriptional heterogeneity facilitating the detection of rare subpopulations at unprecedented resolution. In response to challenges related to coverage and quantity of transcriptome analysis, the lack of unbiased and absolutely quantitative validation methods hampers further improvements. Digital PCR (dPCR) represents such a method as we could show that the inherent partitioning enhances molecular detections by increasing effective mRNA concentrations. We developed a scRT-ddPCR method and validated it using two breast cancer cell lines, MCF7 and BT-474, and bulk methods. ErbB2, a low-abundant transcript in MCF7 cells, suffers from dropouts in scRNA-seq and thus calculated fold changes are biased. Using our scRT-ddPCR, we could improve the detection of ErbB2 and based on the absolute counts obtained we could validate the scRNA-seq fold change. We think this workflow is a valuable addition to the single-cell transcriptomic research toolbox and could even become a new standard in fold change validation because of its reliability, ease of use and increased sensitivity.

molecular biology↗