Ac-YVAD-CMK: Caspase-1 Inhibition Guide

Executive Summary: Ac-YVAD-CMK is listed as a selective, irreversible inhibitor of caspase-1, also known as interleukin-1β-converting enzyme, by the product information. Caspase-1 processes precursor IL-1β and precursor IL-18 during inflammatory signaling, according to a mechanistic review in Nature Reviews Immunology (DOI). Inflammatory caspases can also cleave gasdermin D, a molecular event associated with pyroptotic membrane permeabilization (DOI). A 2024 mouse study found that TMEM16F in Kupffer cells, rather than TMEM16F in T or B cells, was important for protection against Listeria monocytogenes (DOI). The study supplies biological context for a caspase-1 inhibitor experiment, but it does not establish Ac-YVAD-CMK efficacy in that infection model.

Product Identity and Research Context

Ac-YVAD-CMK is the abbreviated name for N-Ac-Tyr-Val-Ala-Asp-CMK. The product is supplied as a solid. Its listed molecular formula is C₂₄H₃₃ClN₄O₈. Its listed molecular weight is 540.99 g/mol. The chemical name is (4S,7S,10S,13S)-13-(2-chloroacetyl)-4-(4-hydroxybenzyl)-7-isopropyl-10-methyl-2,5,8,11-tetraoxo-3,6,9,12-tetraazapentadecan-15-oic acid. These identity and handling data are reported on the C4810 product page.

APExBIO describes Ac-YVAD-CMK as a selective and irreversible caspase-1 inhibitor. The compound is used as an anti-inflammatory research compound in studies of cytokine processing, inflammatory cell death, apoptosis, pyroptosis, and neuroinflammatory mechanisms. These applications are research uses. They do not establish clinical efficacy or a neuroprotective effect in humans.

Biological Rationale

Caspase-1 is an inflammatory cysteine protease. It is activated downstream of inflammasome signaling. Its substrates include pro-IL-1β and pro-IL-18. Processing converts these precursor cytokines into biologically active forms that can be released during inflammatory responses (Lamkanfi et al., mechanistic review).

Pyroptosis is an inflammatory form of programmed cell death. Gasdermin D cleavage creates an amino-terminal pore-forming fragment. The resulting membrane damage can promote cell swelling, lysis, and cytokine release (Shi et al., 2015). Therefore, a caspase-1 inhibitor can be used as a pathway probe when an assay contains caspase-1-dependent cytokine maturation or pyroptotic signaling.

The 2024 TMEM16F study addresses a related but distinct layer of biology. TMEM16F is a calcium-activated lipid scramblase. The authors examined cell type-specific TMEM16F deficiency in mice infected with Listeria monocytogenes. Their results implicated Kupffer-cell TMEM16F in plasma-membrane protection, liver injury control, inflammatory regulation, and metabolic homeostasis (Tang et al., 2024).

Mechanism of Action of Ac-YVAD-CMK

Ac-YVAD-CMK contains the YVAD recognition sequence associated with caspase-1 substrate preference. The product description states that the compound covalently binds the active site of caspase-1. This mechanism explains the designation irreversible caspase-1 inhibitor in the product dossier. Covalent enzyme inhibition should be interpreted as an enzyme-level property. It does not guarantee permanent pathway suppression after compound removal.

The expected experimental chain is direct. Ac-YVAD-CMK inhibits active caspase-1. Reduced caspase-1 activity is expected to reduce cleavage of pro-IL-1β and pro-IL-18. Reduced inflammatory cytokine maturation can lower measurable extracellular IL-1β and IL-18. If the tested model depends on caspase-1-mediated gasdermin D processing, the compound may also reduce pyroptosis-associated readouts. These are pathway-dependent effects and require confirmation in the selected cell type.

Ac-YVAD-CMK is not a general caspase inhibitor based on the supplied product description. It is not described as a direct TMEM16F inhibitor. It is not a plasma-membrane repair reagent. A decrease in cytokine release can reflect altered caspase-1 activity, reduced cell lysis, reduced upstream inflammasome activation, or loss of viable cytokine-producing cells. Orthogonal readouts are therefore essential.

Evidence & Benchmarks

• Ac-YVAD-CMK is listed as a selective and irreversible inhibitor of caspase-1, or ICE, in the product dossier (product information)
• Caspase-1 processes precursor IL-1β and precursor IL-18 during inflammatory signaling (Lamkanfi et al., DOI)
• Inflammatory caspase-dependent gasdermin D cleavage is linked to pyroptotic cell death and membrane permeabilization (Shi et al., 2015, DOI)
• Cell type-specific TMEM16F deficiency identified Kupffer-cell TMEM16F as important for protection against Listeria monocytogenes in mice (Tang et al., 2024, DOI)
• The TMEM16F study associated deficient Kupffer-cell TMEM16F with plasma-membrane rupture and fragmentation, greater liver damage, inflammatory changes, and dysregulated liver metabolism during infection (Tang et al., 2024, DOI)
• The product listing reports solubility up to 20 mg/mL in DMSO and up to 10 mg/mL in dimethylformamide; these are formulation limits rather than universal assay concentrations (product information)

The related article Ac-YVAD-CMK: Selective Caspase-1 Inhibition for Pyroptosis Research emphasizes inhibitor identity and pathway use. This article extends that discussion by separating direct compound evidence from the independent TMEM16F–Kupffer-cell findings.

The article TMEM16F in Kupffer Cells Protects Against Listeria summarizes the cell-specific infection phenotype. This article adds a cautious framework for using Ac-YVAD-CMK to test whether caspase-1-dependent inflammation contributes to that phenotype, without treating the inhibitor as a validated intervention in the published study.

Applications, Limits & Misconceptions

Ac-YVAD-CMK is useful when the experimental question concerns caspase-1 dependence. Suitable designs can compare stimulated cells with vehicle, Ac-YVAD-CMK, and an orthogonal caspase-1 perturbation. Readouts can include caspase-1 activity, mature IL-1β, mature IL-18, gasdermin D cleavage, membrane integrity, and cell viability.

In Kupffer-cell or liver-inflammation research, the compound can test a focused hypothesis: whether caspase-1 activity contributes to cytokine maturation or pyroptosis downstream of a membrane-injury or infection stimulus. That hypothesis is narrower than the finding that TMEM16F protects Kupffer cells. TMEM16F-dependent membrane repair, lipid scrambling, and caspase-1 activity are not interchangeable mechanisms.

Why this cross-domain matters, maturity, and limitations

The cross-domain bridge connects an enzyme inhibitor with a genetic membrane-repair study. The bridge is biologically plausible because membrane damage can drive inflammatory signaling, and caspase-1 can regulate inflammatory cytokine maturation and pyroptosis. The evidence is mature for the general caspase-1 and pyroptosis framework, and it is direct for the TMEM16F–Kupffer-cell phenotype in the cited mouse study. The compound-specific bridge remains a hypothesis-testing strategy because the TMEM16F paper did not report an Ac-YVAD-CMK intervention. A negative inhibitor result would not disprove the role of TMEM16F. A positive result would not prove that Ac-YVAD-CMK repairs membranes or directly targets TMEM16F.

Common Pitfalls or Misconceptions

• Misconception: Ac-YVAD-CMK directly inhibits TMEM16F. The product is described as a caspase-1 inhibitor. The supplied dossier does not identify TMEM16F as its target.
• Misconception: Lower extracellular IL-1β proves reduced pyroptosis. Cytokine measurements should be paired with cell-death, membrane-integrity, and gasdermin D readouts.
• Misconception: Irreversible means every biological effect persists indefinitely. Functional duration depends on exposure, cellular turnover, washout, and assay design.
• Misconception: The Listeria study validates the compound. The study supports a Kupffer-cell TMEM16F mechanism. It is not a direct Ac-YVAD-CMK efficacy study.
• Misconception: This compound is a therapeutic anti-inflammatory agent. The dossier supports biomedical research use, not clinical treatment or human dosing.

Workflow Integration & Parameters

A robust workflow should define the inflammatory stimulus, cell type, exposure sequence, vehicle, and primary endpoint before treatment. The inhibitor should be evaluated with a concentration-response pilot selected for the model. No universal working concentration is established by the supplied product dossier or by the cited TMEM16F study.

Protocol Parameters

• Compound identity: Use Ac-YVAD-CMK, also called N-Ac-Tyr-Val-Ala-Asp-CMK, and record SKU C4810 in the experimental metadata.
• Stock solvent: The product listing reports solubility up to 20 mg/mL in DMSO and up to 10 mg/mL in dimethylformamide; confirm complete dissolution visually and analytically when assay performance is sensitive to precipitation.
• Vehicle control: Match the final DMSO or dimethylformamide content across all treatment groups. Treat vehicle matching as a workflow requirement rather than as a literature-derived dose.
• Storage: Store the solid at −20 °C according to the product information. Use prepared solutions for short-term work only.
• Shipping: The product dossier specifies Blue Ice shipping for small molecules. Confirm receipt temperature and inspect the material before use.
• Pathway readouts: Measure at least one caspase-1 activity or cleavage endpoint, one mature cytokine endpoint, and one independent viability or membrane-integrity endpoint.
• Interpretation: Attribute a cytokine decrease to caspase-1 dependence only when cell number, viability, upstream stimulation, and vehicle exposure are comparable.
• Infection models: Apply appropriate biosafety procedures for Listeria monocytogenes. Do not infer an in vivo protective dose from the product solubility data.

Conclusion & Outlook

Ac-YVAD-CMK is a practical chemical probe for caspase-1-dependent inflammatory signaling. Its intended use is to test relationships among caspase-1 activity, IL-1β maturation, IL-18 maturation, and pyroptosis-associated cell damage. The cited TMEM16F study identifies Kupffer-cell membrane protection as an important determinant of the liver response to Listeria monocytogenes. It does not test Ac-YVAD-CMK.

The most defensible next step is a controlled, orthogonal experiment in which caspase-1 inhibition is combined with cytokine, gasdermin D, membrane-integrity, and viability measurements. Such a design can clarify whether caspase-1 contributes to an observed inflammatory phenotype. It cannot by itself establish direct TMEM16F targeting, membrane repair, therapeutic benefit, or clinical translation.