Eight AI peptide sequencing models, one shared blind spot: missing fragment ions; FDA reviewers said no to all six peptides. HHS cites lab certificates that are not public yet. Updated daily.
A benchmark published in Nature Methods on 3 November 2026 compared eight deep-learning models that read peptide sequences straight from mass spectra, without a sequence database, on three public proteomics datasets. Performance varied between models, but many correct identifications overlapped. Post-processing steps such as iterative refinement, rescoring and reranking gave no or only modest gains. Most errors were the same across models and traced to limited fragment-ion coverage, the gaps in a spectrum where no fragment shows which residue comes next; the authors saw the same limit in database searches with large search spaces. Look-alike residue pairs of equal mass, such as leucine and isoleucine, remain hard to tell apart. These are analytical method results only.
Appendix B of the HHS 503A peptide policy, published in the Federal Register on 30 October 2026 (FR Doc. 2026-22192), says the FDA's drug center, CDER, recommended against listing each of the six peptides. HHS gives three reasons for going ahead: historical use it calls documented and quantified, lot-specific certificates of analysis from FDA-registered facilities that it says were not before CDER, and a view that CDER's safety concerns were inferential or mechanistic rather than observed harm. BioXconomy reported on 4 November 2026 that none of the evidence the HHS document refers to had been provided as of publication. Comments on docket HHS-OASH-2026-0496 close at 11:59 PM Eastern on 13 November 2026. The policy is not an FDA approval.
For research-community awareness only. Not legal advice.
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A simple splice in water joined short peptoid chains, a step toward much longer peptoids
Photo: Image: BioLabs Research
Berkeley Lab's Molecular Foundry reported on 2 November 2026 that a team working with New York University joined two short peptoid chains head to tail using native chemical ligation, a splicing reaction that runs in water and leaves no change in the backbone at the seam. Peptoids are peptide-like chains whose side chains sit on the nitrogen instead of the carbon. The building blocks, 14 to 20 building blocks (residues) long, were made on the Foundry's automated synthesizers. When an unexpected extra mass appeared, the team traced it to a side reaction at the first residue of the chain, seen only when a particular side chain sits in that position. The joined chains still assembled into nanosheets, as the shorter versions do. The work was published in Biochemistry, and a team member says peptoids 100 residues long now look within reach. These are lab chemistry results only.
How long does the HHS peptide policy last? Its own text says it can change, or end
Photo: Image: BioLabs Research
The Department of Health and Human Services published its draft 503A peptide enforcement discretion policy in the Federal Register on 30 October 2026 (FR Doc. 2026-22192). The policy text says it applies only until each of the six peptide substances in its Appendix A is addressed in a final rule, as included or not included on the 503A bulks list. HHS says it may revisit the policy, in whole or in part, if a safety signal or product quality issue arises, and the notice says the policy is not binding on HHS or the public and creates no rights. The notice also tells readers to check the HHS website for the most current version. Comments on docket HHS-OASH-2026-0496 close at 11:59 PM Eastern on 13 November 2026; regulations.gov still showed 0 posted comments on 3 November. The policy is not an FDA approval.
For research-community awareness only. Not legal advice.
