{"id":"9ec24f38-4c58-5d04-8b2c-3042d9a1467b","stable_key":"a9dd23c6-978a-5755-8bd8-f29bd1fe0cda:b3-redox-nadk2-nadh-preference","predicate":"phosphorylates_less_efficiently","statement":"The tested NADH kinase activity of purified human NADK2 Δ62 was about 10% of its NAD+ kinase activity.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"3bc9d7bd-aa8d-551b-a35d-f50429f329e4","mechanism_event_label":"NADK2 could phosphorylate NADH in this assay, but favored NAD+.","subject":{"id":"a3c20ef7-7624-5666-a9c4-a7e678bad211","slug":"nadk2-delta62","display_name":"NADK2 Δ62 recombinant construct","entity_type_key":"protein_state"},"object":{"id":"9fbf2e03-16a9-5ca7-965c-0bfc07ca24da","slug":"nadh","display_name":"NADH","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"3bc9d7bd-aa8d-551b-a35d-f50429f329e4","stable_key":"a9dd23c6-978a-5755-8bd8-f29bd1fe0cda:b3-redox-nadk2-nadh-preference-event","event_type":"biochemical_relationship","label":"NADK2 could phosphorylate NADH in this assay, but favored NAD+.","description":"The tested NADH kinase activity of purified human NADK2 Δ62 was about 10% of its NAD+ kinase activity.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"283ed24b-06a1-50aa-9281-df3bac6ce37e","slug":"nad-plus","display_name":"NAD+","entity_type_key":"small_molecule"},"role":"preferred comparator","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"4aba2a5e-8d06-5304-bb01-c0402b225a94","slug":"nadph","display_name":"NADPH","entity_type_key":"small_molecule"},"role":"NADH phosphorylation product","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"58b974f1-d389-5bf6-81cd-889c44442c42","slug":"atp","display_name":"ATP","entity_type_key":"small_molecule"},"role":"donor","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":"9fbf2e03-16a9-5ca7-965c-0bfc07ca24da","slug":"nadh","display_name":"NADH","entity_type_key":"small_molecule"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/niacin-redox-sources/nadk2-2012.fulltext.txt\", \"locator\": \"Results\", \"start_char\": 9582, \"end_char\": 11594, \"file_sha256\": \"65209c0b4ea7220bc95afdd182e40910f2445345172956e85552d5c6db649648\", \"text_sha256\": \"ffd25dd072f6f8f486b11ca632f28acf37e3ef2b0dbd2b20eecf32fce649eaf1\"}","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":"ATP-dependent NADH versus NAD+ assays","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Relative activity under the reported substrate conditions; not a universal cellular flux ratio.","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":"NADK2 could phosphorylate NADH in this assay, but favored NAD+.","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":"293b5748-d162-5949-8afb-507051b9b883","evidence_kind":"source_excerpt","locator":"Lines 899-910","start_line":899,"end_line":910,"excerpt":"### b3-redox-nadk2-nadh-preference\nThe tested NADH kinase activity of purified human NADK2 Δ62 was about 10% of its NAD+ kinase activity.\nCondition category: normal\nnutrient_topic: Niacin research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: NADK2 could phosphorylate NADH in this assay, but favored NAD+.\norganism: Homo sapiens\ntissue_or_cell_type: Purified enzyme\nexperimental_model: Purified NADK2 Δ62\nlimitations: Relative activity under the reported substrate conditions; not a universal cellular flux ratio.\nexposure: ATP-dependent NADH versus NAD+ assays\nevidence_span: {\"source_cache\": \"artifacts/niacin-redox-sources/nadk2-2012.fulltext.txt\", \"locator\": \"Results\", \"start_char\": 9582, \"end_char\": 11594, \"file_sha256\": \"65209c0b4ea7220bc95afdd182e40910f2445345172956e85552d5c6db649648\", \"text_sha256\": \"ffd25dd072f6f8f486b11ca632f28acf37e3ef2b0dbd2b20eecf32fce649eaf1\"}\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}