{"id":"8951c4fc-3723-52c9-8992-e0965a7228c0","stable_key":"f8641d02-8413-5bd8-92e9-62ad49286e81:asa-acetyl-blocks-the-groove","predicate":"inhibits","statement":"The crystal structures reveal that the acetylated Ser-530 completely blocks access to the hydrophobic groove, that the observed binding pose of salicylate is reflective of the enzyme-inhibitor complex prior to acetylation, and that the observed Thr-530 rotamer in the S530T mutant does not impede access to the groove; differential acetylation of COX-2 purified in various detergent systems and nanodiscs indicates that detergent and lipid binding within the membrane-binding domain alters the rate of the acetylation reaction in vitro.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"e444b660-5c56-5534-a665-2589195a1278","mechanism_event_label":"At high resolution the acetyl group seals the groove completely, and salicylate is caught sitting where aspirin sits before it reacts.","subject":{"id":"cda05399-1c07-5459-b8e2-0edcf5066e94","slug":"acetylated-cox2","display_name":"Aspirin-acetylated cyclooxygenase-2","entity_type_key":"protein_state"},"object":{"id":"b677bbcf-dff6-53ad-b217-1274bea2e43f","slug":"cox-active-site-channel","display_name":"The hydrophobic substrate channel of the cyclooxygenase active site","entity_type_key":"protein_state"},"evidence_count":1,"mechanism_event":{"id":"e444b660-5c56-5534-a665-2589195a1278","stable_key":"f8641d02-8413-5bd8-92e9-62ad49286e81:asa-acetyl-blocks-the-groove-event","event_type":"biochemical_relationship","label":"At high resolution the acetyl group seals the groove completely, and salicylate is caught sitting where aspirin sits before it reacts.","description":"The crystal structures reveal that the acetylated Ser-530 completely blocks access to the hydrophobic groove, that the observed binding pose of salicylate is reflective of the enzyme-inhibitor complex prior to acetylation, and that the observed Thr-530 rotamer in the S530T mutant does not impede access to the groove; differential acetylation of COX-2 purified in various detergent systems and nanodiscs indicates that detergent and lipid binding within the membrane-binding domain alters the rate of the acetylation reaction in vitro.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"5739797a-3699-591b-95fd-f8b80e612713","slug":"salicylate","display_name":"Salicylate / salicylic acid","entity_type_key":"small_molecule"},"role":"pre_acetylation_binder","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"48cd6cab-de3d-53bd-a690-a1f9e5b78a7d","slug":"cox2-ser516","display_name":"Serine 516 of cyclooxygenase-2","entity_type_key":"protein_state"},"role":"homologous_residue","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"7afd60f8-544f-59a5-809f-c985bb5637eb","slug":"steric-blockade","display_name":"Steric blockade of a substrate channel by an introduced side chain","entity_type_key":"cellular_process"},"role":"mechanism","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"cda05399-1c07-5459-b8e2-0edcf5066e94","slug":"acetylated-cox2","display_name":"Aspirin-acetylated cyclooxygenase-2","entity_type_key":"protein_state"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"b677bbcf-dff6-53ad-b217-1274bea2e43f","slug":"cox-active-site-channel","display_name":"The hydrophobic substrate channel of the cyclooxygenase active site","entity_type_key":"protein_state"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/aspirin-research/26859324.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"2d5dab1d6b7576a909c9cef6b5c247e6a399946afbf7ef6d428d67475a363c34\", \"start_char\": 0, \"end_char\": 1553, \"text_sha256\": \"2d5dab1d6b7576a909c9cef6b5c247e6a399946afbf7ef6d428d67475a363c34\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Crystal structures of an S530T murine COX-2 mutant, aspirin-acetylated human COX-2 and human COX-2 with salicylate, at 1.9 to 2.4 angstrom","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Aspirin acetylation and salicylate binding, with an S530T/G533V double mutant and purification in several detergent systems","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Much higher resolution than the 1995 structure and it captures salicylate separately. The authors note that detergent and lipid in the membrane-binding domain change the acetylation rate in vitro, which is a caution about all such measurements.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Aspirin research collection; topical membership is not evidence of a direct clinical effect, and aspirin is recorded separately from salicylate, the metabolite it becomes.","comparator":null,"unit":null,"notes":"","entity":{"slug":"aspirin","display_name":"Aspirin / acetylsalicylic acid","entity_type_key":"drug"}},{"dimension":"organism","value_text":"Mouse and human enzyme","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"At high resolution the acetyl group seals the groove completely, and salicylate is caught sitting where aspirin sits before it reacts.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[asa-p26859324] Crystal Structure of Aspirin-Acetylated Human Cyclooxygenase-2: Insight into the Formation of Products with Reversed Stereochemistry. (2016). https://pubmed.ncbi.nlm.nih.gov/26859324/ DOI: 10.1021/acs.biochem.5b01378","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Crystallised cyclooxygenase-2","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"011abc7d-a58d-56f8-ad41-097e831b2c40","evidence_kind":"source_excerpt","locator":"Lines 156-167","start_line":156,"end_line":167,"excerpt":"### asa-acetyl-blocks-the-groove\nThe crystal structures reveal that the acetylated Ser-530 completely blocks access to the hydrophobic groove, that the observed binding pose of salicylate is reflective of the enzyme-inhibitor complex prior to acetylation, and that the observed Thr-530 rotamer in the S530T mutant does not impede access to the groove; differential acetylation of COX-2 purified in various detergent systems and nanodiscs indicates that detergent and lipid binding within the membrane-binding domain alters the rate of the acetylation reaction in vitro.\nCondition category: normal\nnutrient_topic: Aspirin research collection; topical membership is not evidence of a direct clinical effect, and aspirin is recorded separately from salicylate, the metabolite it becomes.\nplain_language: At high resolution the acetyl group seals the groove completely, and salicylate is caught sitting where aspirin sits before it reacts.\norganism: Mouse and human enzyme\ntissue_or_cell_type: Crystallised cyclooxygenase-2\nexperimental_model: Crystal structures of an S530T murine COX-2 mutant, aspirin-acetylated human COX-2 and human COX-2 with salicylate, at 1.9 to 2.4 angstrom\nlimitations: Much higher resolution than the 1995 structure and it captures salicylate separately. The authors note that detergent and lipid in the membrane-binding domain change the acetylation rate in vitro, which is a caution about all such measurements.\nexposure: Aspirin acetylation and salicylate binding, with an S530T/G533V double mutant and purification in several detergent systems\nevidence_span: {\"source_cache\": \"artifacts/aspirin-research/26859324.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"2d5dab1d6b7576a909c9cef6b5c247e6a399946afbf7ef6d428d67475a363c34\", \"start_char\": 0, \"end_char\": 1553, \"text_sha256\": \"2d5dab1d6b7576a909c9cef6b5c247e6a399946afbf7ef6d428d67475a363c34\"}\n[asa-p26859324] Crystal Structure of Aspirin-Acetylated Human Cyclooxygenase-2: Insight into the Formation of Products with Reversed Stereochemistry. (2016). https://pubmed.ncbi.nlm.nih.gov/26859324/ DOI: 10.1021/acs.biochem.5b01378","model_system":"Crystal structures of an S530T murine COX-2 mutant, aspirin-acetylated human COX-2 and human COX-2 with salicylate, at 1.9 to 2.4 angstrom","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [asa-p26859324] Crystal Structure of Aspirin-Acetylated Human Cyclooxygenase-2: Insight into the Formation of Products with Reversed Stereochemistry. (2016). https://pubmed.ncbi.nlm.nih.gov/26859324/ DOI: 10.1021/acs.biochem.5b01378","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"712cf519-cd27-5a8b-9e2f-961a98d7a27e","stable_key":"import-f8641d02-8413-5bd8-92e9-62ad49286e81","title":"Aspirin: the serine it acetylates, the enzyme that acetylation creates, the dose that separates platelet from vessel wall, and the metabolite that is a different drug (2026-09-22)","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":"93dd4343051c131e40d4fc3c95a978cd65478c13dcdb3f2d42507c49b09cb647","revision_id":"694e8ee7-49ca-5e6c-b58b-8ba8f82c2ad8","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}