Ac-DMQD-pNA , CAS No.907589-02-0

CAS: 907589-02-0 Cat. No.: A1445748 Formule: C₂₆H₃₅N₇O₁₂S Poids moléculaire: 669.66

Storage

Store at -20°C

Shipped In

Ice chest + Ice pads

Vue d’ensemble

Ac-DMQD-pNA is a peptide substrate. Both of the recombinant CgCaspase-1 (rCgCaspase-1) and the C-terminus of CgCaspase-1 (rCgCaspase-1-C) exhibits similar caspase activity towards proteolytic substrate Ac-DMQD-pNA and Ac-DEVD-pNA.

Specifications

Conditions de stockage de stockage

Store at -20°C

Expédié en

Ice chest + Ice pads

Ce produit nécessite l'expédition en chaîne froide. Les services terrestres et autres services économiques ne sont pas disponibles.

Noms et identifiants

Poids moléculaire

669.66

Application Protocols

No manufacturer-validated protocols or application data are provided for this item.

General example workflow (literature; adapt as needed)

1. Stock preparation: Dissolve Ac-DMQD-pNA in anhydrous DMSO to 25 mM. Aliquot, protect from light, and store at −20°C.
2. Assay buffer: 50 mM HEPES, 100 mM NaCl, 2 mM DTT, pH 7.4. Warm to assay temperature (e.g., 37°C).
3. Enzyme pre-incubation: Equilibrate enzyme in buffer for 5–10 min. Include inhibitors or cofactors as required.
4. Initiation: Add substrate to achieve 50–200 µM final concentration with ≤1% DMSO. Mix gently and immediately start recording A405 at 10–30 s intervals.
5. Quantification: Convert A405 to µM pNA using a standard curve prepared in the same buffer and plate format.
6. Analysis: Use initial linear portion (e.g., first 5–10 min) to obtain initial rates. Fit Michaelis–Menten or inhibition models as appropriate.

Controls

• Blank (no enzyme), heat-inactivated enzyme, and known inhibitor control. Confirm linearity with respect to enzyme concentration.

These steps are illustrative only; optimize for your enzyme and instrumentation.

Biological Roles

General biochemical context (literature)

• Protease recognition: The tetrapeptide motif DMQD (Asp–Met–Gln–Asp) has been studied as a recognition sequence for certain cysteine proteases. Chromogenic peptide–pNA substrates leverage this motif to quantify enzymatic cleavage by release of p-nitroaniline.
• Readout chemistry: p-Nitroaniline exhibits strong absorbance near 405 nm, enabling continuous monitoring of proteolysis without additional reagents.
• Enzyme classes: Cysteine proteases with specificity for Asp at P1 and defined preferences at P2–P4 are often profiled using series of pNA-tagged peptides (DEVD, DMQD, VEID, YVAD, etc.) to map selectivity.
• Research applications: Used in fundamental studies of protease catalysis, substrate preference scanning, inhibitor development, and enzymology teaching labs due to straightforward colorimetric kinetics.

Notes

• No clinical or diagnostic use is claimed or supported for this product. It is intended strictly for research use.
• Specific enzyme selectivity for this precise sequence and any kinetic parameters are assay- and lot-dependent; confirm experimentally in your system.

Buffer Applications

Applicability: As a chromogenic peptide substrate, Ac-DMQD-pNA itself is not a buffering agent. However, it is routinely used within defined assay buffers for enzymology.

Typical assay buffers (literature/general)

• Neutral pH systems: 20–50 mM HEPES, Tris, or phosphate buffer, pH 7.2–7.5, 100–150 mM NaCl, 1–5 mM DTT or TCEP if the target protease requires reducing conditions.
• Additives: 0.05% Tween-20 can help reduce nonspecific adsorption; 0.1–1% DMSO from the substrate stock is common. Include BSA (0.1 mg/mL) if enzyme stability is a concern.
• Temperature: Many assays run at 25–37°C; maintain consistent temperature for reproducible kinetics.

Practical guidance

• Prepare a free pNA standard curve in the exact buffer to translate A405 to concentration.
• Verify that buffer components do not absorb significantly at 405 nm or chemically react with the nitroaniline chromophore.
• Filter buffers (0.2 µm) and degas as needed to minimize bubbles and scattering in microplates.

Green Alternatives

Perspective: While Ac-DMQD-pNA itself is the active analyte, greener choices can be made around solvent use and detection modality.

Options (literature/general)

• Solvent footprint reduction: Favor aqueous buffers and minimize DMSO to the lowest enzyme-tolerated concentration (often 0.1–1% v/v). Consider glycerol or PEG-400 as co-solvents if compatible with the enzyme, to reduce reliance on dipolar aprotics.
• Alternative reporters: Replace pNA with fluorogenic reporters with higher sensitivity (e.g., AMC or AFC), allowing lower substrate and solvent usage. Tradeoff: requires fluorescence-capable instrumentation and may introduce inner-filter effects.
• Safer solvents: Where feasible, use ethanol or isopropanol as intermediate wetting agents for rapid dissolution followed by buffer dilution; ensure enzyme compatibility.

Comparison snapshot (general, not product-specific)

• pNA readout: Simple absorbance at 405 nm; moderate sensitivity; compatible with basic plate readers; waste stream typically aqueous with trace DMSO.
• Fluorogenic readout (AMC): Higher sensitivity enabling lower amounts of substrate; requires fluorescence reader; potential photobleaching.

Implementation tips

• Validate enzyme performance at reduced DMSO levels.
• Use on-demand small aliquots to minimize waste and extend shelf life.
• Calibrate with free pNA standards to avoid repeat runs and conserve materials.

Pharmaceutical Uses

This product is not intended for therapeutic or clinical use.

General roles as an analytical reagent (literature/general)

• Enzyme characterization: Used in pharmaceutical R&D labs to characterize protease activity and inhibitor potency via a simple colorimetric readout.
• HTS compatibility: Suitable for primary and secondary screening assays in microplates with absorbance detection, facilitating SAR development for protease inhibitors.
• QC applications: May be incorporated in method development for monitoring recombinant protease preparations or validating assay system performance.

Regulatory note

• No pharmacopeial monograph or excipient status is implied. For any GLP/GMP application, obtain the lot-specific CoA/Specification Sheet and qualify the method and material internally.

Physical Properties

Item-specific physical properties

• Appearance: Not specified for this item; refer to CoA/Spec Sheet.
• Exact MW, formula, elemental analysis: Not specified for this item; refer to CoA/Spec Sheet.
• Melting point, boiling point, density, refractive index: Not specified for this item; refer to CoA/Spec Sheet.

General/literature characteristics for peptide–pNA substrates like Ac-DMQD-pNA

• Physical state: Typically a solid powder, often off-white to light yellow due to the pNA chromophore (literature; not a specification for this item).
• Solubility: Commonly soluble in polar aprotic solvents such as DMSO and DMF; working stocks are often prepared in DMSO and diluted into aqueous assay buffers (literature guidance).
• Aqueous behavior: Limited water solubility as a neat solid; aqueous compatibility increases when pre-dissolved in DMSO and diluted into buffer containing 0.1–1% DMSO (literature).
• Spectral property: p-nitroaniline exhibits a strong absorbance band near 400–405 nm in many assay buffers; an extinction coefficient around 10–11 mM−1·cm−1 at 405 nm is often cited for free pNA, but should be verified under the exact buffer/ionic strength (literature; verify experimentally).

Note: For assay-critical parameters (exact extinction coefficient in your buffer, solubility limits, and purity), confirm with the item’s CoA/Spec Sheet and by in-house calibration curves.

Quality and Grades

Item-specific quality information

• Grade/Purity: Not specified for this item; refer to CoA/Spec Sheet.

Interpretive guidance (general)

• Peptide substrate quality: For enzymatic assays, substrates are commonly offered at ≥95% purity by HPLC with detailed analytical data (HPLC trace, MS). When grade is not specified, request the CoA to confirm purity, counter-ions, residual solvents, and water content.
• Identity confirmation: Typical orthogonal methods include ESI/HRMS, analytical RP-HPLC purity, and, for peptides, sometimes amino acid analysis or NMR of the pNA region.
• Performance implications: Trace impurities can contribute to background absorbance at 405 nm or interact with enzymes. Lot-specific extinction coefficient calibration with free pNA in your assay buffer is recommended.
• Stabilizers: Not specified for this item. In general, peptide–pNA substrates are provided neat without stabilizers; stability is managed by low temperature, desiccation, and protection from light.
• Documentation: For regulated environments, request CoA plus a Specification Sheet indicating acceptance criteria for purity, identity, and storage conditions.

Reaction and Applications

Primary use (research): Chromogenic substrate for protease activity assays in cell-free biochemical workflows. Upon enzymatic cleavage of the DMQD–pNA bond, p-nitroaniline is released, producing an increase in absorbance at ~405 nm (literature).

Typical applications (literature/general)

• Enzyme kinetics: Determination of kcat, KM, and inhibitor potency (IC50/Ki) for proteases that recognize DMQD motifs. Measure initial rates by monitoring A405 over time.
• High-throughput screening: Robust colorimetric readout compatible with 96-/384-well microplates using standard plate readers.
• Mechanistic studies: Mapping substrate specificity via competition assays or by comparing rates across motif variants (e.g., DEVD-, DMQD-, VEID-based substrates; literature context).
• Activity quantification in extracts: Assessment of specific protease activities in clarified lysates or fractionated protein preparations with appropriate controls to confirm protease identity.

Practical tips

• Stock preparation: Prepare 10–50 mM stocks in anhydrous DMSO; verify concentration spectrophotometrically if needed.
• Assay setup: Pre-equilibrate buffer and enzyme, initiate reactions by adding substrate last. Maintain linear range with ≤10% substrate consumption during initial-rate measurements.
• Controls: Include blank (no enzyme), heat-inactivated enzyme, and free pNA standard curve to convert A405 to molar quantities.
• Interferences: Colored compounds, particulates, or high background at 405 nm can confound readings; confirm with orthogonal readouts if needed. Note: This section provides general literature guidance and does not assert target specificity for this item; see “Target Specificity.”

Reaction Conditions

General literature guidance for enzyme assays with peptide–pNA substrates (not item-specific specifications):

• Stock solutions: 10–50 mM in anhydrous DMSO; store aliquots at −20°C protected from light. Dilute into assay buffer immediately before use.
• Typical substrate range: 10–500 µM in the assay, adjusted to stay within the linear initial-rate regime and below Km when determining kcat/Km.
• Buffers: 20–50 mM HEPES or Tris, pH 7.2–7.5, 100–150 mM NaCl. Include 1–5 mM DTT/TCEP if the enzyme requires reducing conditions.
• Temperature: 25–37°C. Maintain constant temperature for kinetic comparability.
• Detection: Monitor A405 with pathlength correction for microplates if available. Use a standard curve of free pNA in the same buffer to convert absorbance to µM product.
• Controls: Blanks without enzyme, heat-inactivated enzyme, and known inhibitors to confirm signal specificity.
• Data quality: Ensure <10% substrate consumption during the initial-rate window; verify absence of significant substrate autohydrolysis by running no-enzyme controls over the assay period.

Note: Enzyme source, co-factors, and exact conditions will vary. Optimize empirically for your protease and report all conditions alongside kinetic parameters.

Safety and Handling

Item-specific hazard information

• Signal Word: Not specified for this item; refer to SDS.
• H-Statements: Not specified for this item; refer to SDS.
• GHS Classification: Not specified for this item; refer to SDS.
• Pictograms: Not specified for this item; refer to SDS.

General laboratory safety guidance (literature/general)

• Potential hazards: Peptide–pNA substrates contain a p-nitroanilide moiety; nitroanilines can be harmful if swallowed, inhaled, or absorbed through skin and may cause eye/skin irritation. Treat as hazardous; avoid dust generation and inhalation.
• PPE: Wear lab coat, safety glasses, and suitable gloves (e.g., nitrile). Use in a fume hood when weighing powders or preparing concentrated stock solutions.
• Incompatibilities: Strong oxidizers and strong acids/bases may degrade peptide bonds or the chromophore. Avoid prolonged exposure to light and moisture to minimize degradation.
• First aid (overview; defer to SDS): If inhaled, move to fresh air; if on skin, wash with soap and water; if in eyes, rinse cautiously with water for several minutes; if ingested, seek medical attention. Provide SDS to medical personnel.
• Spill response: Avoid dust; gently sweep or use HEPA-filtered vacuum. Dissolve residues in appropriate solvent (e.g., DMSO) and absorb on inert material for disposal per institutional guidelines.
• Waste: Dispose of solutions and contaminated disposables as organic chemical waste in accordance with local regulations. Always consult the product’s SDS for authoritative, item-specific safety information.

Solvent Selection

Applicability: As a peptide–pNA substrate, Ac-DMQD-pNA is typically handled as a concentrated stock in an organic solvent and diluted into aqueous assay buffers for enzyme kinetics.

General solvent guidance (literature)

• Primary stock solvent: DMSO is the standard due to excellent solvating power for peptides and pNA conjugates and good miscibility with aqueous buffers.
• Alternatives: DMF or acetonitrile can be used for stock preparation; ensure compatibility with the biological assay and enzyme stability.
• Aqueous buffers: HEPES, Tris, or phosphate buffers (pH 7.2–7.5) with 0.1–1% DMSO are commonly used. Include DTT or TCEP if the target enzyme requires reducing conditions (verify enzyme requirements).
• Polarity/miscibility profile: DMSO and DMF are highly polar and water-miscible, enabling accurate microvolume dosing and rapid dispersion into the assay medium.

Selection considerations

• Enzyme tolerance: Keep final organic cosolvent ≤1–2% v/v unless the enzyme is validated at higher levels.
• Background absorbance: Use high-purity solvents with low UV background at 405 nm to minimize baseline drift.
• Adsorption and carryover: Prepare and store stocks in low-bind tubes; rinse pipette tips to reduce adsorption losses.
• Light and moisture: Protect from light; hygroscopic uptake can alter concentration of DMSO stocks over time.

Storage and Reconstitution

Item-specific conditions

• Storage Conditions: Store at -20°C.
• Shipped In: Ice chest + Ice pads.

General handling guidance (literature/general)

• Light/moisture protection: Keep container tightly closed under dry, inert atmosphere if possible. Protect from light to minimize chromophore degradation.
• Reconstitution: Prepare concentrated stocks (e.g., 10–50 mM) in anhydrous DMSO. Vortex gently until fully dissolved. If needed, warm to room temperature briefly; avoid prolonged heating.
• Aliquoting: Dispense single-use aliquots into low-bind microtubes to avoid repeated freeze–thaw and moisture ingress.
• Working solutions: Dilute into pre-equilibrated assay buffer immediately before use. Keep final DMSO low (typically ≤1% v/v, depending on enzyme tolerance).
• Freeze–thaw: Minimize cycles. Thaw on ice or at room temperature, then promptly return unused aliquots to −20°C.
• Stability checks: Periodically verify performance by running a free pNA calibration and a reference enzyme reaction to detect any loss of activity or increased background over time.

For shelf life, exact purity, and any stabilizers, consult the lot-specific CoA/Specification Sheet.

Structure and Identity

Ac-DMQD-pNA is a chromogenic tetrapeptide substrate in which the N-terminus is acetylated and the C-terminus is coupled to p-nitroanilide (pNA). The peptide sequence DMQD corresponds to Asp–Met–Gln–Asp.

Item-specific identifiers (from Product Data)

• CAS: 907589-02-0
• Molecular Formula: Not specified for this item; refer to CoA/Spec Sheet.
• Molecular Weight: Not specified for this item; refer to CoA/Spec Sheet.
• SMILES: Not specified for this item; refer to CoA/Spec Sheet.
• InChIKey: Not specified for this item; refer to CoA/Spec Sheet.

Structural features (general/literature description)

• Functional groups: N-acetylated N-terminus (amide), peptide backbone (DMQD), C-terminal p-nitroanilide ester/amide linkage featuring a para-nitroaniline chromophore.
• Chromophore: p-nitroanilide releases p-nitroaniline upon enzymatic cleavage, enabling absorbance monitoring near 400–405 nm (literature).
• 2D structure (verbal): Ac–Asp–Met–Gln–Asp–C(=O)–NH–p-nitrophenyl. Side chains: two carboxylates (Asp), a thioether (Met), and an amide (Gln).
• Stereochemistry: Proteinogenic L-amino acids are typically used in such substrates (literature); specific stereochemical confirmation for this catalog item is not specified; refer to CoA/Spec Sheet.

Synthetic Utility

As a finished peptide–pNA conjugate, Ac-DMQD-pNA is primarily an assay reagent rather than a synthetic building block. Nevertheless, general synthetic considerations are relevant for method development and analog design (literature/general):

• Functional handle: The pNA leaving group serves as a chromogenic reporter; systematic variation of the P4–P1 residues (e.g., DMQD → DEVD/VEID variants) enables SAR on protease recognition while maintaining a common readout.
• Peptide synthesis: Typically assembled by solid-phase peptide synthesis (SPPS), followed by N-terminal acetylation and C-terminal coupling to p-nitroaniline via activated ester chemistry.
• Derivatization: Side-chain-protecting group strategies permit installation of noncanonical amino acids (e.g., norleucine in place of Met) to modulate stability or specificity.
• Orthogonal reporters: The same peptide sequence can be rendered fluorogenic (e.g., -AMC) for increased sensitivity or FRET-based for ratiometric assays.

Use in reaction development

• Benchmark substrate in inhibitor profiling workflows and kinetic isotope effect studies.
• Tool compound for calibrating plate readers and validating stopped-flow or continuous-read protocols at 405 nm.

Target Specificity

Item-specific target information is not provided for this catalog entry.

Important notes

• No tested or guaranteed specificity claims are made here. Refer to the literature on DMQD-containing substrates for general context on protease motif recognition, and validate specificity empirically in your system.
• For confirmed target reactivity, please consult the item’s CoA/Specification Sheet or contact technical support with your intended application and assay conditions.

Foire aux questions

How should this product be stored?

Store at ?20 °C. Freezer storage is required to maintain the specified shelf life.

How is this product shipped?

This product ships in an insulated container with ice pads. Unpack on arrival and transfer it to the storage condition stated above.

What are the CAS number, molecular formula and molecular weight?

The CAS Number is 907589-02-0, the molecular formula is C26H35N7O12S, and the molecular weight is 669.66 g/mol.

What documentation is provided?

Available product documentation, including Certificates of Analysis (COA), Safety Data Sheets (SDS), and specification sheets, is shown in the product document area. Document availability and access follow the current site policy.