{"id":"5e9ed0d2-2368-55a3-8189-5aa6468dba9c","stable_key":"f992b796-377d-53bf-a39b-7e5d41dbe194:b5-bio-ppcs-ligation","predicate":"ligates_cysteine_to","statement":"Recombinant human PPCS ligated L-cysteine to 4′-phosphopantothenate in a nucleotide-dependent reaction forming 4′-phosphopantothenoylcysteine.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"f04ebac7-409f-50eb-b06f-e7eb6e93703a","mechanism_event_label":"Cysteine supplies the sulfur-containing portion of the developing CoA molecule.","subject":{"id":"0a912ac0-8179-5884-9cf7-e8a0053e4d21","slug":"ppcs","display_name":"Phosphopantothenoylcysteine synthetase / PPCS","entity_type_key":"protein"},"object":{"id":"7b039e4f-7fa6-5d8e-ac1d-2c115f49fc13","slug":"phosphopantothenate","display_name":"4-Phosphopantothenate","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"f04ebac7-409f-50eb-b06f-e7eb6e93703a","stable_key":"f992b796-377d-53bf-a39b-7e5d41dbe194:b5-bio-ppcs-ligation-event","event_type":"biochemical_relationship","label":"Cysteine supplies the sulfur-containing portion of the developing CoA molecule.","description":"Recombinant human PPCS ligated L-cysteine to 4′-phosphopantothenate in a nucleotide-dependent reaction forming 4′-phosphopantothenoylcysteine.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"ca899f13-50ad-55e5-ab99-329ae0038c74","slug":"l-cysteine","display_name":"L-Cysteine","entity_type_key":"small_molecule"},"role":"cosubstrate","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"58b974f1-d389-5bf6-81cd-889c44442c42","slug":"atp","display_name":"ATP","entity_type_key":"small_molecule"},"role":"activating_cosubstrate","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"c6cf659d-23a5-5c8c-8ef8-79f9d5c19599","slug":"phosphopantothenoylcysteine","display_name":"4′-Phosphopantothenoyl-L-cysteine","entity_type_key":"small_molecule"},"role":"product","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"d47321ac-44bb-5a88-afdb-6435b57a91b9","slug":"amp","display_name":"AMP","entity_type_key":"small_molecule"},"role":"product","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"cd026fef-529f-5e03-b6b5-37ede8ce9127","slug":"pyrophosphate","display_name":"Inorganic pyrophosphate","entity_type_key":"small_molecule"},"role":"product","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""},{"entity":{"id":"0a912ac0-8179-5884-9cf7-e8a0053e4d21","slug":"ppcs","display_name":"Phosphopantothenoylcysteine synthetase / PPCS","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":5,"notes":""},{"entity":{"id":"7b039e4f-7fa6-5d8e-ac1d-2c115f49fc13","slug":"phosphopantothenate","display_name":"4-Phosphopantothenate","entity_type_key":"small_molecule"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":6,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"true","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Recombinant human PPCS, PPCDC and COASY expressed in Escherichia coli; coupled enzyme assays and HPLC reconstitution","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Coupled PPCS assay: 1.5 mM phosphopantothenate, 5 mM cysteine and 1 mM ATP or CTP; 2 mM MgCl2, pH 8.0, 37°C.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Human enzyme expressed in E. coli; assay substrate supply is not evidence that oral cysteine raises human CoA or that low blood cysteine gates B5 repletion.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Pantothenic acid (vitamin B5) research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"pantothenate","display_name":"Pantothenate (vitamin B5)","entity_type_key":"small_molecule"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Cysteine supplies the sulfur-containing portion of the developing CoA molecule.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[b5-bio-daugherty2002] Complete reconstitution of the human coenzyme A biosynthetic pathway via comparative genomics. (2002). https://pubmed.ncbi.nlm.nih.gov/11923312/ DOI: 10.1074/jbc.m201708200","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Purified recombinant protein; no intact tissue","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"6bc1fefd-ff77-5786-ad95-76ebba19c120","evidence_kind":"source_excerpt","locator":"Lines 522-533","start_line":522,"end_line":533,"excerpt":"### b5-bio-ppcs-ligation\nRecombinant human PPCS ligated L-cysteine to 4′-phosphopantothenate in a nucleotide-dependent reaction forming 4′-phosphopantothenoylcysteine.\nCondition category: normal\nnutrient_topic: Pantothenic acid (vitamin B5) research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Cysteine supplies the sulfur-containing portion of the developing CoA molecule.\norganism: Homo sapiens\ntissue_or_cell_type: Purified recombinant protein; no intact tissue\nexperimental_model: Recombinant human PPCS, PPCDC and COASY expressed in Escherichia coli; coupled enzyme assays and HPLC reconstitution\nlimitations: Human enzyme expressed in E. coli; assay substrate supply is not evidence that oral cysteine raises human CoA or that low blood cysteine gates B5 repletion.\nexposure: Coupled PPCS assay: 1.5 mM phosphopantothenate, 5 mM cysteine and 1 mM ATP or CTP; 2 mM MgCl2, pH 8.0, 37°C.\ncross_nutrient: true\n[b5-bio-daugherty2002] Complete reconstitution of the human coenzyme A biosynthetic pathway via comparative genomics. (2002). https://pubmed.ncbi.nlm.nih.gov/11923312/ DOI: 10.1074/jbc.m201708200","model_system":"Recombinant human PPCS, PPCDC and COASY expressed in Escherichia coli; coupled enzyme assays and HPLC reconstitution","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [b5-bio-daugherty2002] Complete reconstitution of the human coenzyme A biosynthetic pathway via comparative genomics. (2002). https://pubmed.ncbi.nlm.nih.gov/11923312/ DOI: 10.1074/jbc.m201708200","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"0716b500-dd0b-5425-b9d0-d88bc9c09e86","stable_key":"import-f992b796-377d-53bf-a39b-7e5d41dbe194","title":"Pantothenic acid (vitamin B5): coenzyme A, 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":"b5a49f5a2373ca6064c9a4e014e052dad2f6f199a82bb09b26b82b831c36110b","revision_id":"78f3e793-f084-5ee2-8703-b661c4b650bf","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}