{
  "abstract": "Macrocyclic peptides are an attractive therapeutic modality capable of engaging challenging protein targets while retaining many favourable drug-like properties. Their high-affinity binding also provides an ideal framework for proximity-driven covalent inhibition through incorporation of latent electrophiles. Phage display enables the high-throughput screening of billion-member macrocyclic peptide libraries; however, existing libraries rely predominantly on cysteine-mediated cyclisation, restricting the range of macrocyclic topologies available for ligand discovery. Here, we report a mild and efficient cyclisation strategy based on a bromomethyl picolinaldehyde (BMP) linker that reacts with a cysteine side chain and the peptide N-terminus to generate a previously unexplored macrocyclic topology incorporating neighbouring pyridine and imidazolidinone rings. The chemistry is compatible with phage display and enabled screening of BMP-cyclised peptide libraries against plasma kallikrein, yielding a potent macrocyclic inhibitor. The BMP-cyclised peptide displayed substantially greater potency than analogous peptides cyclised through either a disulfide bond or the widely used linker 1,4-bis(bromomethyl)benzene (DBMB). Furthermore, comparison with an equivalent DBMB-cyclised library demonstrated that BMP-mediated cyclisation enabled access to binding motifs not identified by conventional cysteine-to-cysteine cyclisation. Finally, positional sulfur(VI) fluoride exchange (SuFEx) electrophile scanning converted the BMP-derived hit into a selective covalent macrocyclic activity-based probe capable of labelling plasma kallikrein in human plasma. Together, these findings establish BMP-mediated cyclisation as a versatile strategy for expanding the topological diversity of phage-displayed macrocycles and accelerating the discovery of both reversible and covalent macrocyclic peptide ligands.",
  "abstract_shown": true,
  "affiliations": [
    "University of Bath"
  ],
  "article_type": "New results",
  "arxiv": null,
  "author_total": 6,
  "authors": [
    {
      "name": "E. Sawtell"
    },
    {
      "name": "M. Barrueco"
    },
    {
      "name": "J. R. Whiteside"
    },
    {
      "name": "C. Williams"
    },
    {
      "name": "M. Laabei"
    },
    {
      "affs": [
        0
      ],
      "name": "S. Lovell"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/3wxaqzte5k1hw.bib",
  "cited_by": 0,
  "doi": "10.64898/2026.09.04.749435",
  "fulltext_url": "https://www.biorxiv.org/content/10.64898/2026.09.04.749435v1.full",
  "id": "3wxaqzte5k1hw",
  "issns": [],
  "landing_url": "https://www.biorxiv.org/content/10.64898/2026.09.04.749435v1",
  "language": null,
  "licence": "CC-BY-NC",
  "licence_label": "CC BY-NC",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by-nc/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "biorxiv",
      "biochemistry"
    ],
    [
      "openalex",
      "1312|Chemical Synthesis and Analysis"
    ]
  ],
  "openalex": "W7211969146",
  "pdf_url": "https://www.biorxiv.org/content/10.64898/2026.09.04.749435v1.full.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-04",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/3wxaqzte5k1hw.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:09Z",
      "native_id": "10.64898/2026.09.04.749435",
      "source": "biorxiv",
      "url": "https://www.biorxiv.org/content/10.64898/2026.09.04.749435v1"
    }
  ],
  "subjects": [
    {
      "field": "biochemistry",
      "origin": "openalex:1312|Chemical Synthesis and Analysis",
      "subfield": "molecular-biology"
    }
  ],
  "title": "Expanding Macrocyclic Topology through Cysteine-to-N-Terminal Cyclisation Enables Covalent Peptide Inhibitor Discovery",
  "title_text": "Expanding Macrocyclic Topology through Cysteine-to-N-Terminal Cyclisation Enables Covalent Peptide Inhibitor Discovery",
  "type": "preprint",
  "updated_at": "2026-10-30T12:20:09Z",
  "url": "https://research.draconitic.com/paper/3wxaqzte5k1hw",
  "venue": "bioRxiv",
  "versions": []
}