Prostaglandin H2: molecular mechanisms & dependencies

How nutrients influence it

Every nutrient with a recorded effect on this component, credited to the nutrient that acted rather than the chapter that recorded it. Open a nutrient to see the findings and the conditions they were measured under.

Human evidence only

How nutrients reach it in more than one step

Chains of two or more recorded steps that end here, grouped by the nutrient they start from. Each step is a separate finding, so a chain is a route a mechanism could take, not proof that it does.

Tracing routes…

What it does

Every recorded relationship this component is part of, grouped by its role. Plain wording comes first; the technical statement follows.

Recorded relationships

Where it participates (unsigned role)

Aspirin treatment of human cyclooxygenase-1 caused time-dependent inactivation of oxygenase activity, whereas aspirin treatment of cyclooxygenase-2 produced an enzyme which retained oxygenase activity but formed exclusively 15-hydroxyeicosatetraenoic acid instead of prostaglandin H2, exclusively of the 15R configuration, with Km values for arachidonate of native and aspirin-treated cyclooxygenase-2 about the same, suggesting arachidonate binds to both in a similar manner.
Aspirin-acetylated cyclooxygenase-2 → 15(R)-hydroxyeicosatetraenoic acid source_derived_draftungraded
Experimental context and source evidence
evidence_span
{"source_cache": "artifacts/aspirin-research/8175750.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "9ba85af90c62b157cf53032375ca703e8b78eff6ddd22ad627bbd7e65965d8e9", "start_char": 0, "end_char": 1786, "text_sha256": "9ba85af90c62b157cf53032375ca703e8b78eff6ddd22ad627bbd7e65965d8e9"}
experimental_model
Human cyclooxygenase-1 and -2 expressed in cos-1 cells treated with aspirin and with carbon-14 labelled aspirin, with a mutant series at Ser-516
exposure
Aspirin acetylation, with S516A, S516N, S516Q and S516M substitutions
limitations
Identifies the site by direct labelling and explains the isoform difference by active site volume. Recombinant enzyme in a heterologous cell line.
nutrient_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. · Aspirin / acetylsalicylic acid
organism
Human enzyme
plain_language
Acetylating the second enzyme does not switch it off; it turns it into a machine that makes something else.
primary_references
[asa-p8175750] Acetylation of human prostaglandin endoperoxide synthase-2 (cyclooxygenase-2) by aspirin. (1994). https://pubmed.ncbi.nlm.nih.gov/8175750/ DOI: 10.1016/s0021-9258(17)36820-5
tissue_or_cell_type
Recombinant cyclooxygenase
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) · lines 208–219
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human cyclooxygenase-1 and -2 expressed in cos-1 cells treated with aspirin and with carbon-14 labelled aspirin, with a mutant series at Ser-516 · source_derived_draft · unverified_draft
### asa-cox2-becomes-a-lipoxygenase Aspirin treatment of human cyclooxygenase-1 caused time-dependent inactivation of oxygenase activity, whereas aspirin treatment of cyclooxygenase-2 produced an enzyme which retained oxygenase activity but formed exclusively 15-hydroxyeicosatetraenoic acid instead of prostaglandin H2, exclusively of the 15R configuration, with Km values for arachidonate of native and aspirin-treated cyclooxygenase-2 about the same, suggesting arachidonate binds to both in a similar manner. Condition category: normal nutrient_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. plain_language: Acetylating the second enzyme does not switch it off; it turns it into a machine that makes something else. organism: Human enzyme tissue_or_cell_type: Recombinant cyclooxygenase experimental_model: Human cyclooxygenase-1 and -2 expressed in cos-1 cells treated with aspirin and with carbon-14 labelled aspirin, with a mutant series at Ser-516 limitations: Identifies the site by direct labelling and explains the isoform difference by active site volume. Recombinant enzyme in a heterologous cell line. exposure: Aspirin acetylation, with S516A, S516N, S516Q and S516M substitutions evidence_span: {"source_cache": "artifacts/aspirin-research/8175750.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "9ba85af90c62b157cf53032375ca703e8b78eff6ddd22ad627bbd7e65965d8e9", "start_char": 0, "end_char": 1786, "text_sha256": "9ba85af90c62b157cf53032375ca703e8b78eff6ddd22ad627bbd7e65965d8e9"} [asa-p8175750] Acetylation of human prostaglandin endoperoxide synthase-2 (cyclooxygenase-2) by aspirin. (1994). https://pubmed.ncbi.nlm.nih.gov/8175750/ DOI: 10.1016/s0021-9258(17)36820-5
Complete structured claim and evidence
Acetylated cyclooxygenase-2 also retains cyclooxygenase activity forming predominantly 15R-configuration prostaglandins, 70% or 62% 15R by radiolabelled substrate or LC-MS respectively, and although the Km of arachidonic acid for the acetylated enzyme was about threefold lower than for uninhibited enzyme the catalytic efficiency for prostaglandin formation was reduced tenfold through a decrease in Vmax.
Aspirin-acetylated cyclooxygenase-2 → 15R-configuration prostaglandins source_derived_draftungraded
Experimental context and source evidence
evidence_span
{"source_cache": "artifacts/aspirin-research/30096040.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "2bd9c817ec4fe31752028634955f604eb00829efc93a72d5fc7e22be7f5739b8", "start_char": 0, "end_char": 1666, "text_sha256": "2bd9c817ec4fe31752028634955f604eb00829efc93a72d5fc7e22be7f5739b8"}
experimental_model
Radiolabelled substrate and LC-MS analysis of aspirin-acetylated COX-2 products, with human leukocytes and platelet aggregation assays
exposure
Aspirin acetylation, with lipopolysaccharide-induced cyclooxygenase-2 in leukocytes and a thromboxane receptor agonist on platelets
limitations
Shows the acetylated enzyme keeps more of its original chemistry than the HETE story implies, and links the product to a measured platelet effect. Isolated cells rather than treated people.
nutrient_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. · Aspirin / acetylsalicylic acid
organism
Human
plain_language
The rerouted enzyme has not stopped making prostaglandins; it makes mirror-image ones, more slowly.
primary_references
[asa-p30096040] Residual cyclooxygenase activity of aspirin-acetylated COX-2 forms 15 R-prostaglandins that inhibit platelet aggregation. (2019). https://pubmed.ncbi.nlm.nih.gov/30096040/ DOI: 10.1096/fj.201801018r
tissue_or_cell_type
Recombinant enzyme and isolated leukocytes and platelets
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) · lines 286–297
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Radiolabelled substrate and LC-MS analysis of aspirin-acetylated COX-2 products, with human leukocytes and platelet aggregation assays · source_derived_draft · unverified_draft
### asa-it-still-makes-prostaglandins Acetylated cyclooxygenase-2 also retains cyclooxygenase activity forming predominantly 15R-configuration prostaglandins, 70% or 62% 15R by radiolabelled substrate or LC-MS respectively, and although the Km of arachidonic acid for the acetylated enzyme was about threefold lower than for uninhibited enzyme the catalytic efficiency for prostaglandin formation was reduced tenfold through a decrease in Vmax. Condition category: normal nutrient_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. plain_language: The rerouted enzyme has not stopped making prostaglandins; it makes mirror-image ones, more slowly. organism: Human tissue_or_cell_type: Recombinant enzyme and isolated leukocytes and platelets experimental_model: Radiolabelled substrate and LC-MS analysis of aspirin-acetylated COX-2 products, with human leukocytes and platelet aggregation assays limitations: Shows the acetylated enzyme keeps more of its original chemistry than the HETE story implies, and links the product to a measured platelet effect. Isolated cells rather than treated people. exposure: Aspirin acetylation, with lipopolysaccharide-induced cyclooxygenase-2 in leukocytes and a thromboxane receptor agonist on platelets evidence_span: {"source_cache": "artifacts/aspirin-research/30096040.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "2bd9c817ec4fe31752028634955f604eb00829efc93a72d5fc7e22be7f5739b8", "start_char": 0, "end_char": 1666, "text_sha256": "2bd9c817ec4fe31752028634955f604eb00829efc93a72d5fc7e22be7f5739b8"} [asa-p30096040] Residual cyclooxygenase activity of aspirin-acetylated COX-2 forms 15 R-prostaglandins that inhibit platelet aggregation. (2019). https://pubmed.ncbi.nlm.nih.gov/30096040/ DOI: 10.1096/fj.201801018r
Complete structured claim and evidence

The events it takes part in

A mechanism often involves more than two components. These are the full events, with every participant and its role.

Situations it appears in

Low-supply and faulty-machinery situations recorded in the chapters where this component plays a part.

In the sources

Preserved passages that mention this component, quoted exactly. Open one to read it in context.

Open hypotheses

Proposed ideas that involve this component. They are labeled as hypotheses and do not change any recorded statement.

This is a research prototype built from draft material. It is not medical advice, and its statements still await verification against the original studies.

Prostaglandin H2