Protein sequencing buzz

Proteins are the cell’s working parts, and a March 18 paper in *Nature Biotechnology* described a way to read single peptide molecules by first converting their sequence into DNA. (nature.com) The method came from a Stanford-led team and uses a modified Edman degradation, a stepwise chemistry that removes one amino acid at a time from a peptide’s front end. Each released amino acid is tagged with a peptide-specific DNA barcode and then turned into a DNA readout that standard high-throughput sequencers can process. (nature.com; news.stanford.edu) The paper reported single-amino-acid resolution, full sequence coverage in millions of reads, and discrimination between native peptides and peptides carrying post-translational modifications, the chemical edits cells add after a protein is made. The authors deposited sequencing data in the National Center for Biotechnology Information Sequence Read Archive under BioProjects PRJNA1420480 and PRJNA1423337. (nature.com) Protein sequencing is harder than DNA sequencing because proteins are built from 20 amino acids, not four DNA bases, and proteins cannot be copied the way DNA can. Stanford’s H. Tom Soh said the point of the new chemistry was to run biology “in reverse” so existing DNA machines could do the reading. (news.stanford.edu) Most proteomics still relies on mass spectrometry, which has become the primary method for identifying proteins in complex biological samples. Reviews in *Nature* and *Molecular & Cellular Proteomics* say that approach is powerful, but direct single-molecule protein sequencing remains a central unsolved problem. (nature.com; mcponline.org) That gap matters because cells with the same DNA can carry different protein forms, called proteoforms, after splicing, truncation, or chemical modification. A 2024 *Nature* paper on nanopore reading said single-molecule access to full-length proteins could expose that hidden diversity and map modifications such as phosphorylation on individual molecules. (nature.com) The Stanford paper does not sequence full-length intact proteins yet; it sequences peptides, which are shorter protein fragments. The authors described the work as a framework for high-throughput, de novo single-molecule protein sequencing rather than a finished replacement for mass spectrometry. (nature.com) Other groups are pushing a different route with nanopores, tiny holes that sense molecules as motors pull them through. A 2025 *Nature Biotechnology* review and a 2024 *Nature* News & Views article described nanopore protein sequencing as promising, but still in development. (nature.com; nature.com) The immediate appeal of the reverse-translation approach is that it plugs protein reading into the DNA-sequencing infrastructure laboratories already use at scale. Stanford said that could help researchers find rare proteins and potential immunotherapy targets in samples too small or too complex for current workflows. (news.stanford.edu) The buzz around the paper reflects a simple idea with big practical stakes: if protein sequences can be turned into DNA-style data, biologists may be able to count and compare the cell’s actual machinery with much finer detail than before. For now, the result is a new entrant in a race that still includes mass spectrometry and nanopores. (nature.com; nature.com)