{"id":"d078b82a-3b5f-5d02-9a07-a316351c763b","stable_key":"aaa7baba-8689-56ab-ba1e-b71542bcb8e9:iodine-syn-human-tpo-t4-synthesis","predicate":"catalyzes","statement":"Recombinant human TPO catalyzed T4 formation from recombinant human TG in the direct TPO-versus-lactoperoxidase comparison.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"5bf1a886-33a8-5b3b-845c-ddd17ad5f042","mechanism_event_label":"Human TPO can drive hormone formation on human thyroglobulin.","subject":{"id":"b196ae88-ffbd-5930-b693-3ded1d143544","slug":"human-tpo-ectodomain-1-838","display_name":"Human TPO ectodomain residues 1–838","entity_type_key":"protein_state"},"object":{"id":"4f349271-a12f-54a0-be84-2115499c7348","slug":"human-thyroglobulin-t4-bearing","display_name":"Human thyroglobulin containing covalent T4 residues","entity_type_key":"protein_state"},"evidence_count":1,"mechanism_event":{"id":"5bf1a886-33a8-5b3b-845c-ddd17ad5f042","stable_key":"aaa7baba-8689-56ab-ba1e-b71542bcb8e9:iodine-syn-human-tpo-t4-synthesis-event","event_type":"biochemical_relationship","label":"Human TPO can drive hormone formation on human thyroglobulin.","description":"Recombinant human TPO catalyzed T4 formation from recombinant human TG in the direct TPO-versus-lactoperoxidase comparison.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"d5e001d7-78aa-5636-8891-07672ef87e0f","slug":"tpo","display_name":"Human thyroid peroxidase","entity_type_key":"protein"},"role":"full_length_parent","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"ab42f761-f2c0-52e6-876b-12df0d1d03d7","slug":"thyroglobulin","display_name":"Human thyroglobulin","entity_type_key":"protein"},"role":"protein_substrate","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"ca877817-8e7f-5da4-b3c5-2a6345ddfae0","slug":"tg-bound-diiodotyrosyl-residues","display_name":"Thyroglobulin-bound diiodotyrosyl residues","entity_type_key":"chemical_species"},"role":"coupling_residues","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"83b11ca6-52c7-5a1b-8c39-d9cdf89244e3","slug":"iodide","display_name":"Iodide ion","entity_type_key":"ion"},"role":"iodination_substrate","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"da9d64bc-69d4-5d97-90a4-8f0ed03e0ac8","slug":"hydrogen-peroxide","display_name":"Hydrogen peroxide","entity_type_key":"small_molecule"},"role":"oxidant","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""},{"entity":{"id":"2e1f7e0a-8b54-5ea3-9d34-01e7167f9097","slug":"heme","display_name":"Heme","entity_type_key":"small_molecule"},"role":"TPO_prosthetic_group","stoichiometry":null,"state_label":"","sequence_order":5,"notes":""},{"entity":{"id":"f2b25f38-ec94-57d0-a46d-dd0fee45f01e","slug":"thyroxine","display_name":"T4","entity_type_key":"small_molecule"},"role":"product_after_proteolysis","stoichiometry":null,"state_label":"","sequence_order":6,"notes":""},{"entity":{"id":"b196ae88-ffbd-5930-b693-3ded1d143544","slug":"human-tpo-ectodomain-1-838","display_name":"Human TPO ectodomain residues 1–838","entity_type_key":"protein_state"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":7,"notes":""},{"entity":{"id":"4f349271-a12f-54a0-be84-2115499c7348","slug":"human-thyroglobulin-t4-bearing","display_name":"Human thyroglobulin containing covalent T4 residues","entity_type_key":"protein_state"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":8,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"true","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/iodine-synthesis-sources/32025030.txt\", \"start_char\": 37661, \"end_char\": 38631, \"text_sha256\": \"edbab2cbd62ebd263ef59f543f10aad3692d3a3983ef5abad904e697ea34ca04\", \"text_characters\": 970, \"note\": \"Exact publisher passage retained in the cited local source cache; locator and digest supplied here.\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Human TG cryo-EM, recombinant HEK293T-expressed TG and site-directed mutants","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Extended Data Fig.6c: 0.1 micromolar TG, 1 mM KI, glucose/glucose oxidase peroxide supply, 10 minutes at 37 C; TPO added at fivefold the LPO concentration to compensate for approximately 20% heme occupancy; T4 measured after Pronase digestion.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"This identifies the TPO-containing assay arm; most TG mutagenesis experiments used LPO. The measured T4 was liberated by assay proteolysis after formation on TG.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Iodine research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"iodine","display_name":"Iodine","entity_type_key":"nutrient_element"}},{"dimension":"organism","value_text":"Homo sapiens TG and TPO; HEK293T TG expression and insect-cell TPO expression","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Human TPO can drive hormone formation on human thyroglobulin.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[iodine-syn-tg2020] The structure of human thyroglobulin. (2020). https://pubmed.ncbi.nlm.nih.gov/32025030/ DOI: 10.1038/s41586-020-1995-4","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Purified-protein reconstitution","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"d8079ea4-86f9-5733-93e7-87002d3b1d3a","evidence_kind":"source_excerpt","locator":"Lines 842-854","start_line":842,"end_line":854,"excerpt":"### iodine-syn-human-tpo-t4-synthesis\nRecombinant human TPO catalyzed T4 formation from recombinant human TG in the direct TPO-versus-lactoperoxidase comparison.\nCondition category: normal\nnutrient_topic: Iodine research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Human TPO can drive hormone formation on human thyroglobulin.\norganism: Homo sapiens TG and TPO; HEK293T TG expression and insect-cell TPO expression\ntissue_or_cell_type: Purified-protein reconstitution\nexperimental_model: Human TG cryo-EM, recombinant HEK293T-expressed TG and site-directed mutants\nlimitations: This identifies the TPO-containing assay arm; most TG mutagenesis experiments used LPO. The measured T4 was liberated by assay proteolysis after formation on TG.\nexposure: Extended Data Fig.6c: 0.1 micromolar TG, 1 mM KI, glucose/glucose oxidase peroxide supply, 10 minutes at 37 C; TPO added at fivefold the LPO concentration to compensate for approximately 20% heme occupancy; T4 measured after Pronase digestion.\ncross_nutrient: true\nevidence_span: {\"source_cache\": \"artifacts/iodine-synthesis-sources/32025030.txt\", \"start_char\": 37661, \"end_char\": 38631, \"text_sha256\": \"edbab2cbd62ebd263ef59f543f10aad3692d3a3983ef5abad904e697ea34ca04\", \"text_characters\": 970, \"note\": \"Exact publisher passage retained in the cited local source cache; locator and digest supplied here.\"}\n[iodine-syn-tg2020] The structure of human thyroglobulin. (2020). https://pubmed.ncbi.nlm.nih.gov/32025030/ DOI: 10.1038/s41586-020-1995-4","model_system":"Human TG cryo-EM, recombinant HEK293T-expressed TG and site-directed mutants","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [iodine-syn-tg2020] The structure of human thyroglobulin. (2020). https://pubmed.ncbi.nlm.nih.gov/32025030/ DOI: 10.1038/s41586-020-1995-4","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"76da623d-a34a-5a5c-a942-d7571a85c486","stable_key":"import-aaa7baba-8689-56ab-ba1e-b71542bcb8e9","title":"Iodine: thyroid hormone production, deficiency, excess and nutrient interactions (2026-09-17)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. 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