Severability (contract law) — what survives when a clause is struck, and what survives a KMT2A break

[
  {
    "bio": "KMT2A, a 3,969-residue protein built from separable modules (AT-hooks, CXXC, PHD1-3, bromodomain, FYRN/FYRC, TAD, SET)",
    "analog": "a long contract composed of separately identifiable clauses"
  },
  {
    "bio": "the translocation breakpoint",
    "analog": "a court striking a clause from the agreement"
  },
  {
    "bio": "MBM1 (aa 4-15, RWRFP), retained in every recurrent KMT2A fusion",
    "analog": "the consideration — strike it and there is no contract at all"
  },
  {
    "bio": "the CXXC domain, retained in all leukemogenic fusions, which fixes where the protein acts on the genome",
    "analog": "the clause identifying the subject matter of the bargain"
  },
  {
    "bio": "PHD1-3, the bromodomain and SET, lost in the fusion",
    "analog": "collateral covenants severable without defeating the main purpose"
  },
  {
    "bio": "the requirement that the junction be in frame and that the product fold",
    "analog": "the blue-pencil rule — strike words, never rewrite them"
  },
  {
    "bio": "the major breakpoint cluster region lying in the CXXC-to-PHD1 inter-domain linker",
    "analog": "severance permitted only between clauses, not through the middle of one"
  },
  {
    "bio": "the reciprocal AFF1::KMT2A product, expressed in only about 45% of t(4;11) cases",
    "analog": "the severed remainder, which may or may not itself be an enforceable agreement"
  },
  {
    "bio": "non-recurrent breaks outside the cluster regions",
    "analog": "severance that defeats the main purpose and voids the whole contract"
  }
]

[
  "hyp-severability-linker-constrained-breakpoints",
  "hyp-reciprocal-product-as-enforceable-remainder"
]

{
  "_why": "Added by king sweep 2026-09-21 (Q82 corrections-owed #3). This entry quotes the menin-MBM1 53 nM figure. That number is NOT comparable to the KMT2A CXXC-DNA affinities without stating its buffer, and the omission is how a 1,300-fold 'discrepancy' was manufactured.",
  "value": "53 nM",
  "motif": "KMT2A MBM1, residues 4-15, FITC-labelled peptide at 15 nM",
  "method": "fluorescence polarisation",
  "buffer": "50 mM Tris, pH 7.5, 50 mM NaCl, 1 mM DTT",
  "nacl_mM": 50,
  "companion_itc": "72 nM by ITC, 50 mM phosphate pH 7.5, 50 mM NaCl, 1 mM beta-mercaptoethanol, 27 C",
  "source_pmid": "20961854",
  "source_quote": "\"in the FP buffer (50 mM Tris, pH 7.5, 50 mM NaCl, 1 mM DTT) used for binding experiments (Kd measurements)\" -- Grembecka 2010 JBC, Methods, fetched and read from PMC3003368 on 2026-09-21",
  "do_not_compare_naively": {
    "against": "KMT2A CXXC-DNA Kd 44 uM (PMID 20010842, Cierpicki 2010)",
    "because": "that measurement was made at 300 mM NaCl -- verbatim from its Methods, \"50 mM phosphate buffer (pH 7.1), 300 mM NaCl, 2 mM DTT at 25 C\" (PMC2908503, read 2026-09-21) -- SIX-FOLD more salt, on a salt-sensitive protein-DNA contact, against a hydrophobic peptide pocket that is not.",
    "best_matched_pair": "44 uM at 300 mM NaCl vs the 5.7 uM tagless CXXC measurement at 150 mM NaCl gives 108-fold against menin, not ~1,000-fold",
    "see": "ana-the-menin-affinity-comparison-was-made-at-one-sixth-the-salt"
  },
  "added": "2026-09-21"
}

{
  "_why": "Added by king sweep 2026-09-21 (cycle 46). This entry quotes the KMT2A CXXC-DNA 44 uM. That number is a property of five choices, not of the molecule, and quoting it bare is how this graph manufactured a 1,300-fold 'discrepancy' with the menin contact.",
  "value": "44 uM",
  "construct": "isolated CXXC domain, KMT2A 1147-1203, untagged, 15N-labelled",
  "ligand": "DNA pal oligonucleotide, one CpG element",
  "method": "NMR titration",
  "buffer": "50 mM phosphate, pH 7.1, 300 mM NaCl, 2 mM DTT, 25 C",
  "nacl_mM": 300,
  "source_pmid": "20010842",
  "source_quote": "\"Determination of the dissociation constants by NMR for the CXXC domain (MLL 1147-1203) and mutants was performed by titration of 15N-labeled protein with concentrated solutions of DNA pal oligonucleotide. Experiments were carried out in 50 mM phosphate buffer (pH 7.1), 300 mM NaCl, 2 mM DTT at 25 C.\" -- Cierpicki 2010 NSMB, Methods, fetched and read from PMC2908503 on 2026-09-21. The result sentence reads \"The wild type protein yielded a Kd of 44 uM\".",
  "this_is_the_high_salt_end": "300 mM NaCl is roughly twice physiological ionic strength and SIX TIMES the 50 mM the menin-MBM1 53 nM was measured in. The same domain measured tagless at 150 mM NaCl gives 5.7 uM -- 7.7-fold tighter from salt alone.",
  "do_not_compare_naively": {
    "against": "menin-MBM1 53 nM (PMID 20961854), measured at 50 mM NaCl by FP",
    "best_matched_pair": "108-fold, not ~1,000-fold",
    "see": "ana-the-menin-affinity-comparison-was-made-at-one-sixth-the-salt"
  },
  "added": "2026-09-21"
}