{"id":"7e4c19b0-a247-5f6a-b3a2-01d59e8dfdc0","stable_key":"88eb7407-f147-558b-889b-0c89c4e0aa4a:spermidine-dohh-high-polyamine","predicate":"inhibits","statement":"Spermidine inhibited rat-testis deoxyhypusine hydroxylase in vitro, less potently than spermine.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"2b7ceaa6-2ffc-572a-b983-a005d9e5ac6d","mechanism_event_label":"More substrate upstream does not guarantee more activity downstream.","subject":{"id":"7014993c-468f-5c6b-ab04-80c87f9dfd9f","slug":"spermidine","display_name":"Spermidine","entity_type_key":"small_molecule"},"object":{"id":"194d6251-f771-57d6-a43c-f3342a13150f","slug":"rat-dohh","display_name":"Rat deoxyhypusine hydroxylase / Dohh","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"2b7ceaa6-2ffc-572a-b983-a005d9e5ac6d","stable_key":"88eb7407-f147-558b-889b-0c89c4e0aa4a:spermidine-dohh-high-polyamine-event","event_type":"observed_relationship","label":"More substrate upstream does not guarantee more activity downstream.","description":"Spermidine inhibited rat-testis deoxyhypusine hydroxylase in vitro, less potently than spermine.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"7014993c-468f-5c6b-ab04-80c87f9dfd9f","slug":"spermidine","display_name":"Spermidine","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"194d6251-f771-57d6-a43c-f3342a13150f","slug":"rat-dohh","display_name":"Rat deoxyhypusine hydroxylase / Dohh","entity_type_key":"protein"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"ded80d0b-9076-5034-9e87-cd38f7dafae5","slug":"spermine","display_name":"Spermine","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"evidence_access","value_text":"Primary abstract","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Rat testis enzyme; comparative polyamine inhibition kinetics.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"High-concentration enzyme inhibition is not a contradiction of cellular hypusination rescue; no human inhibitory threshold established.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Spermidine collection; molecular form, preparation, species, exposure and manipulation remain explicit.","comparator":null,"unit":null,"notes":"","entity":{"slug":"spermidine","display_name":"Spermidine","entity_type_key":"small_molecule"}},{"dimension":"plain_language","value_text":"More substrate upstream does not guarantee more activity downstream.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"Inhibition of deoxyhypusine hydroxylase by polyamines and by a deoxyhypusine peptide. · 1989 · https://pubmed.ncbi.nlm.nih.gov/2765563/ · DOI 10.1016/0167-4838(89)90195-7","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"77be67f5-fd1a-5443-9883-4f156e061549","evidence_kind":"source_excerpt","locator":"Lines 70-76","start_line":70,"end_line":76,"excerpt":"## spermidine-dohh-high-polyamine\nMore substrate upstream does not guarantee more activity downstream.\nSpermidine inhibited rat-testis deoxyhypusine hydroxylase in vitro, less potently than spermine.\nModel: Rat testis enzyme; comparative polyamine inhibition kinetics.\nLimitations: High-concentration enzyme inhibition is not a contradiction of cellular hypusination rescue; no human inhibitory threshold established.\nEvidence access: Primary abstract\nInhibition of deoxyhypusine hydroxylase by polyamines and by a deoxyhypusine peptide. · 1989 · https://pubmed.ncbi.nlm.nih.gov/2765563/ · DOI 10.1016/0167-4838(89)90195-7","model_system":"Rat testis enzyme; comparative polyamine inhibition kinetics.","directness":"reported_statement","verification_status":"source_derived_draft","notes":"Original curation paraphrase; evidence access and experimental limitations specified.","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"4348f3f8-0180-58a3-b61c-55d03bb322d2","stable_key":"import-88eb7407-f147-558b-889b-0c89c4e0aa4a","title":"Spermidine: biosynthesis, hypusination, transport and cross-nutrient mechanisms (2026-09-19)","document_type":"imported_text","citation_label":"AI-assisted research curation; primary references, access levels and experimental limitations individually identified. 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