{"id":"1b731bb9-145d-55a6-9114-a1594c5654ba","stable_key":"a9dd23c6-978a-5755-8bd8-f29bd1fe0cda:b3-redox-nadk2-polyphosphate","predicate":"uses_phosphoryl_donor","statement":"Purified human NADK2 Δ62 also supported NADP+ formation using inorganic polyphosphate preparations as phosphate donors.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"c0748819-747c-59b9-846a-6e437e34b806","mechanism_event_label":"The recombinant mitochondrial enzyme accepted some polyphosphate preparations in vitro.","subject":{"id":"a3c20ef7-7624-5666-a9c4-a7e678bad211","slug":"nadk2-delta62","display_name":"NADK2 Δ62 recombinant construct","entity_type_key":"protein_state"},"object":{"id":"ed43cfaf-76de-5e21-afcb-dc704ebf1ef2","slug":"polyphosphate","display_name":"Inorganic polyphosphate","entity_type_key":"chemical_species"},"evidence_count":1,"mechanism_event":{"id":"c0748819-747c-59b9-846a-6e437e34b806","stable_key":"a9dd23c6-978a-5755-8bd8-f29bd1fe0cda:b3-redox-nadk2-polyphosphate-event","event_type":"biochemical_relationship","label":"The recombinant mitochondrial enzyme accepted some polyphosphate preparations in vitro.","description":"Purified human NADK2 Δ62 also supported NADP+ formation using inorganic polyphosphate preparations as phosphate donors.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"283ed24b-06a1-50aa-9281-df3bac6ce37e","slug":"nad-plus","display_name":"NAD+","entity_type_key":"small_molecule"},"role":"acceptor","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"be6e4670-953f-5a4e-97da-1e536a54e0e4","slug":"nadp-plus","display_name":"NADP+","entity_type_key":"small_molecule"},"role":"product","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"bff427ab-35f9-59c2-bb24-fd5953bbaec2","slug":"magnesium-ion","display_name":"Mg2+","entity_type_key":"ion"},"role":"assay metal","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"a3c20ef7-7624-5666-a9c4-a7e678bad211","slug":"nadk2-delta62","display_name":"NADK2 Δ62 recombinant construct","entity_type_key":"protein_state"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"ed43cfaf-76de-5e21-afcb-dc704ebf1ef2","slug":"polyphosphate","display_name":"Inorganic polyphosphate","entity_type_key":"chemical_species"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"Uses phosphate polymers in a magnesium-containing enzyme assay, not a dietary phosphorus intervention.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/niacin-redox-sources/nadk2-2012.fulltext.txt\", \"locator\": \"Results\", \"start_char\": 11596, \"end_char\": 12294, \"file_sha256\": \"65209c0b4ea7220bc95afdd182e40910f2445345172956e85552d5c6db649648\", \"text_sha256\": \"f371b72f3f7104e6b2b1f4f28ec55e04b18b931383b51a3258872db0809a10d9\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Purified NADK2 Δ62","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Metaphosphate, hexametaphosphate and tetrapolyphosphate tested","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"In vitro substrate capacity; physiological flux from polyphosphate in human mitochondria was not established. Monomeric phosphate is not interchangeable with these polymers.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Niacin research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"niacin","display_name":"Niacin (vitamin B3)","entity_type_key":"nutrient_element"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"The recombinant mitochondrial enzyme accepted some polyphosphate preparations in vitro.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[nadk2-2012] Identification and characterization of a human mitochondrial NAD kinase. (2012). https://pubmed.ncbi.nlm.nih.gov/23212377/ DOI: 10.1038/ncomms2262","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Purified enzyme","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"3bc1b048-1381-5d99-956e-c0cd54edfac5","evidence_kind":"source_excerpt","locator":"Lines 885-897","start_line":885,"end_line":897,"excerpt":"### b3-redox-nadk2-polyphosphate\nPurified human NADK2 Δ62 also supported NADP+ formation using inorganic polyphosphate preparations as phosphate donors.\nCondition category: normal\nnutrient_topic: Niacin research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: The recombinant mitochondrial enzyme accepted some polyphosphate preparations in vitro.\norganism: Homo sapiens\ntissue_or_cell_type: Purified enzyme\nexperimental_model: Purified NADK2 Δ62\nlimitations: In vitro substrate capacity; physiological flux from polyphosphate in human mitochondria was not established. Monomeric phosphate is not interchangeable with these polymers.\nexposure: Metaphosphate, hexametaphosphate and tetrapolyphosphate tested\ncross_nutrient: Uses phosphate polymers in a magnesium-containing enzyme assay, not a dietary phosphorus intervention.\nevidence_span: {\"source_cache\": \"artifacts/niacin-redox-sources/nadk2-2012.fulltext.txt\", \"locator\": \"Results\", \"start_char\": 11596, \"end_char\": 12294, \"file_sha256\": \"65209c0b4ea7220bc95afdd182e40910f2445345172956e85552d5c6db649648\", \"text_sha256\": \"f371b72f3f7104e6b2b1f4f28ec55e04b18b931383b51a3258872db0809a10d9\"}\n[nadk2-2012] Identification and characterization of a human mitochondrial NAD kinase. (2012). https://pubmed.ncbi.nlm.nih.gov/23212377/ DOI: 10.1038/ncomms2262","model_system":"Purified NADK2 Δ62","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [nadk2-2012] Identification and characterization of a human mitochondrial NAD kinase. (2012). https://pubmed.ncbi.nlm.nih.gov/23212377/ DOI: 10.1038/ncomms2262","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"a62b7b5b-786a-57e9-85e9-67c6912a5054","stable_key":"import-a9dd23c6-978a-5755-8bd8-f29bd1fe0cda","title":"Niacin: NAD metabolism, deficiency 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. Not publisher full text.","file_path":"","sha256":"a8cac59639322f74812ce12eef338c2f6c385c04cc4af6ab511fc7c972f0c2e6","revision_id":"bec8fc45-12e7-5f75-a814-5d72ed015d01","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}