{"id":"d48fca58-c0f5-54b0-8472-631329591c2f","stable_key":"88eb7407-f147-558b-889b-0c89c4e0aa4a:spermidine-spermine-first-step","predicate":"supports_partial_reaction","statement":"Spermine bound human DHPS and generated a smaller NADH fluorescence response than spermidine.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"7a60bb4d-4b42-5968-9bc5-d130efff1c8f","mechanism_event_label":"A related polyamine can participate in part of the chemistry.","subject":{"id":"ded80d0b-9076-5034-9e87-cd38f7dafae5","slug":"spermine","display_name":"Spermine","entity_type_key":"small_molecule"},"object":{"id":"33684e20-5166-55d6-9196-0793156787f1","slug":"dhps","display_name":"DHPS","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"7a60bb4d-4b42-5968-9bc5-d130efff1c8f","stable_key":"88eb7407-f147-558b-889b-0c89c4e0aa4a:spermidine-spermine-first-step-event","event_type":"observed_relationship","label":"A related polyamine can participate in part of the chemistry.","description":"Spermine bound human DHPS and generated a smaller NADH fluorescence response than spermidine.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"ded80d0b-9076-5034-9e87-cd38f7dafae5","slug":"spermine","display_name":"Spermine","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"33684e20-5166-55d6-9196-0793156787f1","slug":"dhps","display_name":"DHPS","entity_type_key":"protein"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"7014993c-468f-5c6b-ab04-80c87f9dfd9f","slug":"spermidine","display_name":"Spermidine","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"evidence_access","value_text":"Primary full text","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Single-turnover fluorescence and structural assays; apparent spermine KD about 81 micromolar.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"The assay probes an initial reaction step, not successful cellular replacement of spermidine for complete eIF5A hypusination.","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":"A related polyamine can participate in part of the chemistry.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"Half Way to Hypusine-Structural Basis for Substrate Recognition by Human Deoxyhypusine Synthase. · 2020 · https://pubmed.ncbi.nlm.nih.gov/32235505/ · DOI 10.3390/biom10040522","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"b7e779ea-55ab-5b5e-b06d-1201cae0085d","evidence_kind":"source_excerpt","locator":"Lines 30-36","start_line":30,"end_line":36,"excerpt":"## spermidine-spermine-first-step\nA related polyamine can participate in part of the chemistry.\nSpermine bound human DHPS and generated a smaller NADH fluorescence response than spermidine.\nModel: Single-turnover fluorescence and structural assays; apparent spermine KD about 81 micromolar.\nLimitations: The assay probes an initial reaction step, not successful cellular replacement of spermidine for complete eIF5A hypusination.\nEvidence access: Primary full text\nHalf Way to Hypusine-Structural Basis for Substrate Recognition by Human Deoxyhypusine Synthase. · 2020 · https://pubmed.ncbi.nlm.nih.gov/32235505/ · DOI 10.3390/biom10040522","model_system":"Single-turnover fluorescence and structural assays; apparent spermine KD about 81 micromolar.","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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