Component

Serine 516 of cyclooxygenase-2

Serine 516 of cyclooxygenase-2. Species, exposure and limitations are retained in each linked claim.

5 recorded relationships. Experimental role, claim status and evidence remain attached to each record.

Read recorded mechanisms Open recursive mind map

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.

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

What acts on it

  1. When microsomal human cyclooxygenase-2 was incubated with acetyl-carbon-14 labelled aspirin the enzyme was acetylated, while an S516A mutant which retains enzyme activity was not acetylated, indicating that Ser-516 is the site of aspirin acetylation and is homologous to the active site serine of cyclooxygenase-1; an S516N mutant was catalytically active whereas an S516Q mutant lacked cyclooxygenase but retained peroxidase activity, and because in cyclooxygenase-1 the smaller asparagine substitution suffices to eliminate cyclooxygenase activity the active site of cyclooxygenase-2 is slightly larger.

    Aspirin / acetylsalicylic acid → Serine 516 of cyclooxygenase-2 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
    The labelled acetyl group lands on one serine, and the second enzyme’s pocket is roomier, which is why the two behave differently.
    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 221–232

    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-ser516-is-the-site When microsomal human cyclooxygenase-2 was incubated with acetyl-carbon-14 labelled aspirin the enzyme was acetylated, while an S516A mutant which retains enzyme activity was not acetylated, indicating that Ser-516 is the site of aspirin acetylation and is homologous to the active site serine of cyclooxygenase-1; an S516N mutant was catalytically active whereas an S516Q mutant lacked cyclooxygenase but retained peroxidase activity, and because in cyclooxygenase-1 the smaller asparagine substitution suffices to eliminate cyclooxygenase activity the active site of cyclooxygenase-2 is slightly larger. 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 labelled acetyl group lands on one serine, and the second enzyme’s pocket is roomier, which is why the two behave differently. 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

Where it participates (unsigned role)

  1. 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.

    Aspirin-acetylated cyclooxygenase-2 → The hydrophobic substrate channel of the cyclooxygenase active site source_derived_draftungraded
    Experimental context and source evidence
    evidence_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"}
    experimental_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
    exposure
    Aspirin acetylation and salicylate binding, with an S530T/G533V double mutant and purification in several detergent systems
    limitations
    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.
    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
    Mouse and human enzyme
    plain_language
    At high resolution the acetyl group seals the groove completely, and salicylate is caught sitting where aspirin sits before it reacts.
    primary_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
    tissue_or_cell_type
    Crystallised cyclooxygenase-2

    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 156–167

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · 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 · source_derived_draft · unverified_draft

    ### asa-acetyl-blocks-the-groove 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. 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: At high resolution the acetyl group seals the groove completely, and salicylate is caught sitting where aspirin sits before it reacts. organism: Mouse and human enzyme tissue_or_cell_type: Crystallised cyclooxygenase-2 experimental_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 limitations: 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. exposure: Aspirin acetylation and salicylate binding, with an S530T/G533V double mutant and purification in several detergent systems evidence_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"} [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
    Complete structured claim and evidence

  2. 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

  3. The production of 15-HETE by aspirin-modified cyclooxygenase-2 was sensitive to inhibition by most non-steroidal anti-inflammatory drugs including selective cyclooxygenase-2 inhibitors and the inhibition by indomethacin was time-dependent, but two potent structurally related drugs, diclofenac and meclofenamic acid, did not inhibit either the acetylated enzyme or the S516M mutant, so Ser516 plays an important role in the interaction with fenamate inhibitors.

    Diclofenac → 15(R)-hydroxyeicosatetraenoic acid source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/aspirin-research/9016346.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "2cc2efefceabbee7bb4f1052db8fc86ee218409fe56981cf92b707c7b0ef531b", "start_char": 0, "end_char": 1899, "text_sha256": "2cc2efefceabbee7bb4f1052db8fc86ee218409fe56981cf92b707c7b0ef531b"}
    experimental_model
    Kinetic characterisation of aspirin-acetylated cyclooxygenase-2 and the S516M mutant against a panel of non-steroidal anti-inflammatory drugs
    exposure
    Aspirin acetylation and the methionine mutant, tested with indomethacin, diclofenac, meclofenamic acid and selective inhibitors
    limitations
    Quantifies how efficient the new activity is, which most descriptions of the switch do not. Purified and recombinant enzyme rather than intact cells.
    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
    Enzyme
    plain_language
    Two common anti-inflammatories cannot touch the rerouted enzyme, because they needed the serine aspirin has taken.
    primary_references
    [asa-p9016346] Altered sensitivity of aspirin-acetylated prostaglandin G/H synthase-2 to inhibition by nonsteroidal anti-inflammatory drugs. (1997). https://pubmed.ncbi.nlm.nih.gov/9016346/ DOI: 10.1124/mol.51.1.52
    tissue_or_cell_type
    Cyclooxygenase-2

    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 273–284

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Kinetic characterisation of aspirin-acetylated cyclooxygenase-2 and the S516M mutant against a panel of non-steroidal anti-inflammatory drugs · source_derived_draft · unverified_draft

    ### asa-fenamates-do-not-block-it The production of 15-HETE by aspirin-modified cyclooxygenase-2 was sensitive to inhibition by most non-steroidal anti-inflammatory drugs including selective cyclooxygenase-2 inhibitors and the inhibition by indomethacin was time-dependent, but two potent structurally related drugs, diclofenac and meclofenamic acid, did not inhibit either the acetylated enzyme or the S516M mutant, so Ser516 plays an important role in the interaction with fenamate inhibitors. 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: Two common anti-inflammatories cannot touch the rerouted enzyme, because they needed the serine aspirin has taken. organism: Enzyme tissue_or_cell_type: Cyclooxygenase-2 experimental_model: Kinetic characterisation of aspirin-acetylated cyclooxygenase-2 and the S516M mutant against a panel of non-steroidal anti-inflammatory drugs limitations: Quantifies how efficient the new activity is, which most descriptions of the switch do not. Purified and recombinant enzyme rather than intact cells. exposure: Aspirin acetylation and the methionine mutant, tested with indomethacin, diclofenac, meclofenamic acid and selective inhibitors evidence_span: {"source_cache": "artifacts/aspirin-research/9016346.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "2cc2efefceabbee7bb4f1052db8fc86ee218409fe56981cf92b707c7b0ef531b", "start_char": 0, "end_char": 1899, "text_sha256": "2cc2efefceabbee7bb4f1052db8fc86ee218409fe56981cf92b707c7b0ef531b"} [asa-p9016346] Altered sensitivity of aspirin-acetylated prostaglandin G/H synthase-2 to inhibition by nonsteroidal anti-inflammatory drugs. (1997). https://pubmed.ncbi.nlm.nih.gov/9016346/ DOI: 10.1124/mol.51.1.52
    Complete structured claim and evidence

  4. While prostaglandin synthesis by both isoforms is inhibited by aspirin, 15-R-hydroxyeicosatetraenoic acid synthesis by cyclooxygenase-2 but not cyclooxygenase-1 is stimulated by preincubation with aspirin, and enzyme activity and inhibitor sensitivity studies of mutants provide evidence that Ser516 is the aspirin acetylation site of human cyclooxygenase-2 and that substitution of a methionine at this position can mimic the effects of aspirin acetylation on enzyme activity.

    Cyclooxygenase-2 with methionine substituted at position 516 → 15(R)-hydroxyeicosatetraenoic acid source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/aspirin-research/8143845.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "ddf63e3296e1f35a88de948bc23fda6654c2eaf247b1d6d3987e95989c966f93", "start_char": 0, "end_char": 903, "text_sha256": "ddf63e3296e1f35a88de948bc23fda6654c2eaf247b1d6d3987e95989c966f93"}
    experimental_model
    Mutants of the putative acetylation site of human cyclooxygenase-2 expressed in COS-7 cells by recombinant vaccinia virus
    exposure
    Substitution at Ser516, including methionine, compared with aspirin preincubation
    limitations
    A second, independent identification of the same residue with a substitution that mimics the acetylated state. Vaccinia-driven expression in a heterologous 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
    Putting a methionine where the acetyl group would go reproduces the switch without any drug.
    primary_references
    [asa-p8143845] Mutation of serine-516 in human prostaglandin G/H synthase-2 to methionine or aspirin acetylation of this residue stimulates 15-R-HETE synthesis. (1994). https://pubmed.ncbi.nlm.nih.gov/8143845/ DOI: 10.1016/0014-5793(94)80579-2
    tissue_or_cell_type
    Recombinant cyclooxygenase-2

    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 234–245

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Mutants of the putative acetylation site of human cyclooxygenase-2 expressed in COS-7 cells by recombinant vaccinia virus · source_derived_draft · unverified_draft

    ### asa-methionine-mimics-acetyl While prostaglandin synthesis by both isoforms is inhibited by aspirin, 15-R-hydroxyeicosatetraenoic acid synthesis by cyclooxygenase-2 but not cyclooxygenase-1 is stimulated by preincubation with aspirin, and enzyme activity and inhibitor sensitivity studies of mutants provide evidence that Ser516 is the aspirin acetylation site of human cyclooxygenase-2 and that substitution of a methionine at this position can mimic the effects of aspirin acetylation on enzyme activity. 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: Putting a methionine where the acetyl group would go reproduces the switch without any drug. organism: Human enzyme tissue_or_cell_type: Recombinant cyclooxygenase-2 experimental_model: Mutants of the putative acetylation site of human cyclooxygenase-2 expressed in COS-7 cells by recombinant vaccinia virus limitations: A second, independent identification of the same residue with a substitution that mimics the acetylated state. Vaccinia-driven expression in a heterologous line. exposure: Substitution at Ser516, including methionine, compared with aspirin preincubation evidence_span: {"source_cache": "artifacts/aspirin-research/8143845.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "ddf63e3296e1f35a88de948bc23fda6654c2eaf247b1d6d3987e95989c966f93", "start_char": 0, "end_char": 903, "text_sha256": "ddf63e3296e1f35a88de948bc23fda6654c2eaf247b1d6d3987e95989c966f93"} [asa-p8143845] Mutation of serine-516 in human prostaglandin G/H synthase-2 to methionine or aspirin acetylation of this residue stimulates 15-R-HETE synthesis. (1994). https://pubmed.ncbi.nlm.nih.gov/8143845/ DOI: 10.1016/0014-5793(94)80579-2
    Complete structured claim and evidence

In the sources

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

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

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