Liver Esterase (HL) Activity Assay Kit (Micro Method)

Cat. No.: L1522152

QUALITÉ & PURETÉ BioReagent

Vue d’ensemble

Hepatic lipase is a lipolytic enzyme synthesized in hepatocytes and localized on the surface of endothelial cells in the perisinusoidal spaces of the liver as well as on the microvilli of hepatocytes facing these spaces. It promotes the conversion of cholesterol in lipoproteins into steroid hormones. Elevated plasma HL activity can lead to increased levels of small LDL particles, thereby accelerating the development of atherosclerosis. Determination Principle: Hepatic lipase hydrolyzes α-naphthyl acetate to produce α-naphthol, which reacts with Fast Blue B salt to form a purple-red azo compound with a characteristic absorption peak at 595 nm. The color intensity is positively correlated with hepatic lipase activity within a certain range.

Spécifications

Spécifications et pureté

BioReagent

Grade

BioReagent

Application

Enzyme activity assay

Detection instrument

Microplate reader,Visible Spectrophotometer

Detection wavelength

595nm

Stockage et expédition

Conditions de stockage de stockage

Store at 2-8°C,Protected from light

Expédié en

Wet ice

Stabilité et stockage

Store at 2-8℃ for 6 months. Store in the dark.

Application Protocols

Item-specific, validated protocols are Not specified for this item; consult the kit booklet. Below is a generalized micro-method workflow for liver esterase activity measurements (literature-style guidance):

• Sample preparation:
  • Homogenize ~10–20% (w/v) liver tissue in ice-cold buffer (e.g., 50 mM phosphate, pH 7.4). Clarify by centrifugation (e.g., 10–15 min, 10,000 × g, 4°C). Determine protein concentration.
  • For cultured cells, wash, scrape, and sonicate in buffer; clear lysate similarly.
• Reagent preparation:
  • Prepare substrate stock (e.g., in DMSO or buffer) freshly. Protect light-sensitive reagents. Equilibrate all reagents to assay temperature.
• Assay setup (96- or 384-well plate or microcuvette):
  • Combine buffer, substrate working solution, and sample to a defined final volume (e.g., 100–200 μL). Keep final organic cosolvent ≤1–2% v/v if used.
  • Include blanks (no enzyme), matrix controls, and inhibitor control(s) to confirm specificity.
• Incubation and measurement:
  • Incubate at 25–37°C. Record kinetic signal (absorbance/fluorescence) or stop at defined time for endpoint readout, using wavelengths appropriate to the reporter (kit-specific).
• Calculations:
  • Use a standard curve or known response factor (extinction coefficient/fluorescence calibration) to convert signal to product formed. Normalize to time and protein (U/mg) or report relative activity.
• QC tips:
  • Verify linearity with respect to time and protein. Reject runs with >10% deviation from linearity in the initial rate window. Replicate wells (n≥3) to estimate precision.

Adjust volumes and timing per the specific kit instructions when available.

Biological Roles

General/literature context for hepatic esterases (carboxylesterases):

• Function: Liver esterases are serine hydrolases that catalyze hydrolysis of carboxylic esters, converting esterified xenobiotics and endogenous lipids into their corresponding acids and alcohols. The catalytic mechanism involves a nucleophilic serine within a catalytic triad (Ser–His–Asp/Glu) and an oxyanion hole that stabilizes the tetrahedral intermediate.
• Physiological role: In the liver, major carboxylesterase isoforms (e.g., human CES1 and CES2) contribute to first-pass metabolism, detoxification, and the bioactivation/deactivation of ester-containing prodrugs. They also participate in lipid remodeling and triglyceride/cholesteryl ester turnover.
• Species differences: Expression and substrate specificity differ across species (human, mouse, rat, dog), impacting translational extrapolation of in vitro data.
• Regulation: Expression is modulated by nuclear receptors (e.g., PXR, CAR), diet, disease state, and exposure to inducers/inhibitors. Post-translational processing (e.g., glycosylation) affects localization and activity.
• Inhibition: Organophosphates, carbamates, and certain urea/amide derivatives act as esterase inhibitors; some act irreversibly via covalent modification of the active-site serine, while others are reversible competitive inhibitors.

Relevance to this kit:

• The kit quantifies total esterase activity in samples, providing a functional endpoint that integrates isoform expression, post-translational state, and matrix factors. Item-specific substrate selectivity and isoform bias are Not specified for this item; refer to the kit booklet if isoform preference is disclosed.

Buffer Applications

While this is not a buffer product, successful liver esterase assays depend on appropriate buffer systems that preserve activity and minimize non-enzymatic ester hydrolysis.

General/literature guidance (informational):

• pH range: Many hepatic esterases exhibit optimal activity near neutral to mildly basic pH (≈7.0–8.0). Validate activity vs pH for your matrix to avoid off-optimum conditions.
• Common systems: 50–100 mM phosphate (pH 7.0–7.4) for robust buffering and low UV background; HEPES (pH 7.4–7.8) for minimal temperature-dependent pH shift; Tris (pH 7.5–8.0) for enhanced activity in some preparations but note Tris can interact with acyl-enzyme intermediates in rare cases—verify with controls.
• Additives: 0.1% nonionic detergent can stabilize membranes and reduce nonspecific adsorption; 0.5–1 mM EDTA can chelate trace metals to reduce oxidative degradation of substrates, though excessive chelation is usually unnecessary for serine esterases.
• Ionic strength: Maintain physiological salt (e.g., 100–150 mM NaCl) for enzyme stability in cell/tissue extracts.
• Temperature control: Buffer pH is temperature-dependent; equilibrate to assay temperature before measurements.

Item-specific buffer composition, pH, and any provided concentrates: Not specified for this item; refer to the kit insert for definitive formulations and preparation steps.

Green Alternatives

This micro-method assay format inherently supports greener lab practices by reducing reagent volumes, waste generation, and energy consumption.

Greening considerations (general):

• Volume minimization: Microplate or microcuvette workflows cut solvent and plastic consumption per data point compared to macro assays.
• Aqueous-first design: Favor aqueous buffers and limit organic cosolvent (e.g., DMSO/ACN) to the lowest level that dissolves the substrate, typically ≤1% v/v.
• Light management: Protect light-sensitive reagents with amberware to prevent degradation and extend shelf life, reducing waste.
• Waste segregation: Separate halogenated/non-halogenated organic waste and heavy metal-containing developers (if any) for compliant disposal.

Comparison of common choices (general, illustrative):

• DMSO vs acetonitrile for substrate stocks:
  • DMSO: Higher solvating power; non-volatile; easier to dose accurately; may inhibit enzymes at higher %.
  • Acetonitrile: More volatile (facilitates removal); lower viscosity; potentially less inhibitory at low %; higher VOC burden.
• Plastic vs glass microplates:
  • COC/PS plates are convenient but single-use; glass plates or reusable cuvettes reduce plastic waste if compatible with assay chemistry and throughput needs.

Item-specific greener alternatives or validated conditions are Not specified for this item; refer to the kit documentation for any recommended practices unique to this SKU.

Pharmaceutical Uses

This product is for research use only and is not intended for diagnostic or therapeutic applications. In a pharmaceutical R&D context, liver esterase activity assays are widely used as in vitro tools.

Typical uses in pharma and DMPK labs (general/literature):

• ADME screening: Evaluate hydrolytic stability of ester-containing drug candidates in liver-derived matrices (microsomes, S9, hepatocytes) to inform clearance predictions and prodrug design.
• Structure–metabolism relationships: Map substituent effects on esterase susceptibility; identify metabolic soft spots for medicinal chemistry optimization.
• Inhibitor assessment: Characterize potential off-target esterase inhibition by lead compounds to anticipate drug–drug or drug–xenobiotic interactions.
• Bioactivation studies: Assess conversion rates of ester prodrugs to active acids/alcohols under hepatic conditions.
• Formulation and stability: Monitor ex vivo ester hydrolysis during sample handling to guide excipient choice and storage conditions for preclinical samples.

Documentation note:

• Any pharmacopeial status, validated methods, or regulatory acceptance specific to this SKU are Not specified for this item; consult the kit documentation and institutional SOPs for use in GLP/GMP environments.
• Always corroborate kit-derived kinetic parameters with orthogonal analytical methods (e.g., LC–MS) when making development decisions.

Physical Properties

This listing is an assay kit containing multiple reagents; single-compound physical constants do not apply.

Item-specific specifications:

• Appearance: Not specified for this item; refer to CoA/Spec Sheet.
• Molecular formula, molecular weight: Not specified for this item; refer to CoA/Spec Sheet.

General/literature notes (informational only; not product specifications):

• Common esterase assay substrates (e.g., p-nitrophenyl esters for colorimetric assays or fluorogenic esters such as fluorescein diacetate/4-MU esters) have distinct solubility and stability profiles and are often supplied as concentrated stock solutions or lyophilized solids to be reconstituted in dry solvent or buffer immediately before use to minimize hydrolysis. The exact substrate and its properties for this item are not specified.
• Assay buffers used for hepatic esterase activity are typically near neutral pH (≈7.0–8.0) and formulated to maintain enzyme stability while minimizing non-enzymatic hydrolysis (literature guidance).

If precise physical characteristics of any component are required (e.g., solvent composition, pH, extinction coefficients), consult the product’s CoA/Spec Sheet and the kit booklet. Those values, when provided, supersede any general literature information.

Quality and Grades

Item-specific grade:

• BioReagent grade (per Product Data).

What BioReagent typically implies (general guidance):

• Prepared for research and biochemical applications with attention to purity, enzyme compatibility, and low background in optical detection. Reagents are selected/formulated to minimize assay interference (e.g., low absorbance/fluorescence impurities) and to ensure batch-to-batch consistency suitable for quantitative work.

Assay kit quality considerations (general):

• Substrate quality: Low baseline hydrolysis and defined extinction coefficient/quantum yield help achieve high signal-to-noise and linearity.
• Buffer and additives: Stringent control of pH, ionic strength, and chelators/detergents ensures enzyme stability without inhibiting esterase activity.
• Controls and calibration: Many kits include a positive control enzyme and/or standards to validate performance; the presence and specifications of such controls in this item are Not specified for this item; refer to CoA/Spec Sheet.
• Documentation: Lot-specific CoA and a protocol booklet typically define performance metrics (e.g., linear range, LOD/LOQ, precision). Those data are not provided here and should be consulted directly for this SKU.

Compliance and traceability:

• For research use only (per Product Data). Not intended for diagnostic or clinical use. Use lot-specific documentation for QC acceptance criteria in regulated settings (e.g., GLP), if applicable.

Reaction and Applications

This kit enables quantitative measurement of liver esterase (carboxylesterase) activity in biological samples. It is suited for micro-volume workflows, conserving sample and reagents while supporting throughput.

Typical research applications (general/literature):

• Enzyme activity profiling in hepatic tissue homogenates, microsomes, S9 fractions, primary hepatocytes, or liver-derived cell lines.
• ADME/DMPK studies: Assess hydrolytic stability of ester-containing prodrugs or agrochemicals; rank-order intrinsic esterase activity across species or conditions.
• Toxicology and chemical biology: Evaluate inhibition by organophosphates/carbamates or screen small molecules for off-target esterase inhibition.
• Bioprocess and sample QC: Monitor esterase activity in lysate preparations to inform sample handling (e.g., risk of ex vivo ester hydrolysis).

Practical considerations (general):

• Sample prep: Homogenize tissues in ice-cold buffer; clarify by centrifugation. Normalize input by protein concentration (e.g., BCA) to report activity in units per mg protein.
• Linear range: Optimize enzyme amount and time to maintain initial-rate conditions (linear product formation vs time and protein).
• Controls: Include no-enzyme (blank), heat-inactivated sample, and known inhibitor controls to confirm specificity for esterases.
• Interferences: Endogenous chromophores/fluorophores and turbidity can bias optical readouts; include matrix-matched blanks and read dual-wavelength (if supported) to correct background.

Item-specific assay principle, wavelength(s), and units: Not specified for this item; consult the kit insert for the exact detection chemistry and calculation method.

Reaction Conditions

The “reaction” monitored is enzymatic hydrolysis of esters by hepatic esterases. Specific, item-validated assay parameters are Not specified for this item; refer to the kit booklet. The following are general/literature guidelines for planning and optimizing esterase activity assays:

• Temperature: 25–37°C. Many labs standardize at 37°C for physiological relevance; use a plate reader with temperature control for consistency.
• pH: Near-neutral to mildly basic (≈7.0–8.0), depending on substrate and matrix.
• Buffer: 50–100 mM phosphate, HEPES, or Tris; maintain ionic strength (100–150 mM NaCl) if using cell/tissue extracts.
• Enzyme source: Clarified liver homogenate, microsomes, S9, or purified enzyme. Normalize by protein concentration (e.g., 0.05–1 mg/mL total protein in-well) to keep initial-rate conditions.
• Organic cosolvent: Keep ≤1–2% v/v DMSO or acetonitrile final, unless validated otherwise.
• Time course: 5–60 min typical; ensure linearity with respect to time and protein.
• Detection: Colorimetric or fluorimetric endpoints/kinetic readouts depending on substrate (wavelengths vary with reporter). Calibrate with standards if applicable.
• Controls: No-enzyme blank; heat-inactivated sample; known inhibitor (e.g., BNPP for CES inhibition, general literature) to confirm specificity; matrix-matched background correction.
• Data reduction: Report as μmol/min/mg protein (U/mg) or relative activity vs control; apply molar response factors (extinction coefficient or calibration curve) as appropriate.

Always validate these parameters with the actual kit documentation for this SKU.

Safety and Handling

Item-specific safety information:

• GHS classification, signal word, hazard statements, and pictograms: Not specified for this item; refer to the SDS for each component.
• Storage: Store at 2–8°C, protected from light (per Product Data). Keep tightly closed.
• Shipping: Wet ice (per Product Data).

General laboratory safety for enzyme activity assay kits (informational; defer to SDS):

• PPE: Wear lab coat, safety glasses, and appropriate chemical-resistant gloves. Work in a well-ventilated area or fume hood when handling volatile solvents or stop solutions.
• Incompatibilities: Avoid mixing oxidizers or acids/bases indiscriminately with kit reagents. Substrates and chromophores/fluorophores can be light-sensitive—minimize light exposure and use amber containers as indicated.
• Special risks: Some esterase substrates or developers may be irritants or harmful if inhaled/ingested; certain fluorogenic substrates can be photosensitizers. Dry organic solvents (if used for substrate stocks) are flammable—keep away from ignition sources. Prevent accidental skin exposure; many reporters stain.
• First aid (overview): In case of skin/eye contact, rinse with water for ≥15 min and remove contaminated clothing; if inhaled, move to fresh air; if ingested, seek medical attention. Always follow the specific SDS instructions.
• Waste: Collect aqueous and organic waste streams separately. Treat solutions containing chromogenic/fluorogenic reporters as hazardous laboratory waste according to institutional and local regulations.

Solvent Selection

This product is an enzymatic assay kit; solvent selection focuses on maintaining enzyme activity and substrate stability rather than on dissolution of a synthetic reagent.

General/literature guidance for hepatic esterase assays:

• Aqueous buffers: Near-neutral pH buffers (e.g., phosphate, HEPES, Tris) are commonly used. Ionic strength should be controlled (e.g., 50–150 mM total salts) to stabilize the enzyme while limiting non-enzymatic hydrolysis.
• Organic cosolvents: Many ester substrates are hydrophobic and may be prepared as concentrated stocks in DMSO or acetonitrile. Keep final organic cosolvent ≤1–2% v/v in the assay to avoid enzyme inhibition (typical literature practice). Validate tolerance for your sample matrix.
• Detergents: If needed to solubilize substrates or membrane fractions, use nonionic detergents at low concentrations below their CMC to avoid altering enzyme activity; verify compatibility empirically.
• Metal ions and chelators: Carboxylesterases are serine hydrolases and generally do not require metal cofactors; excessive EDTA or divalent cations can affect activity indirectly—keep consistent across samples and standards.

Comparison (general):

• DMSO vs acetonitrile as stock solvent: DMSO offers better solubility for many substrates but is more inhibitory to some enzymes at >1% v/v; acetonitrile evaporates faster and may reduce background but can denature proteins at higher levels. Choose based on substrate solubility and enzyme tolerance.

Item-specific solvent or buffer recommendations: Not specified for this item; refer to the kit booklet/CoA.

Storage and Reconstitution

Item-specific instructions:

• Storage conditions: Store at 2–8°C, protected from light (per Product Data). Keep components tightly closed when not in use.
• Shipping: Supplied on wet ice (per Product Data).

General handling and reconstitution guidance for assay kits (informational; follow the kit booklet when available):

• Light-sensitive reagents: Store in amber vials; minimize exposure during setup. Return to cold storage promptly after use.
• Reconstitution: If any components are lyophilized, reconstitute only with the specified solvent/buffer and volume. Mix gently to avoid foaming. Note the final concentration and label with reconstitution date.
• Aliquoting: For reagents susceptible to degradation (e.g., substrates, enzymes), prepare single-use aliquots to avoid repeated freeze–thaw or room-temperature excursions.
• Working solutions: Prepare fresh on the day of use. Discard any remaining working solutions after the experiment unless stability is explicitly documented.
• Temperature equilibration: Bring buffers and plates to assay temperature (e.g., 25–37°C) before initiating reactions to ensure consistent kinetics.
• Stability/shelf life: Not specified for this item; refer to CoA/Spec Sheet for lot-specific expiry and post-reconstitution stability.

Always prioritize the lot-specific documentation packaged with this SKU for authoritative storage and preparation instructions.

Structure and Identity

This product is an enzymatic activity assay kit designed to quantify total liver (hepatic) esterase activity using a micro-volume format. It is not a single defined chemical entity; rather, it comprises multiple reagents optimized for an in vitro enzymatic readout.

Item-specific facts from Product Data:

• SKU: L1522152
• Product name: Liver Esterase (HL) Activity Assay Kit (Micro Method)
• Grade/Purity: BioReagent
• Storage: 2–8°C, protected from light
• Shipped on: Wet ice
• Research use only

Identifiers (item-specific):

• CAS, CID, InChIKey, SMILES, molecular formula, molecular weight: Not specified for this item; refer to CoA/Spec Sheet.

General description (chemistry/biochemistry context):

• Targeted function: Hydrolytic cleavage of carboxylic esters by hepatic/carboxylesterases to yield alcohols and acids.
• Kit nature: Typically includes an esterase substrate, assay buffer(s), stop/developer solution and/or cofactors, and positive control enzyme or reference material (general/literature; exact components vary by kit and are not specified here).
• Readout: Common esterase assays use colorimetric or fluorimetric reporters formed upon ester hydrolysis (general information; consult the kit insert for the exact detection modality of this item).

2D/functional features (general):

• The biochemical transformation monitored is R–COOR′ + H2O → R–COO− + R′–OH, catalyzed by serine hydrolases containing a catalytic triad (Ser–His–Asp/Glu). The assay quantifies the rate or extent of product formation under controlled conditions.

Synthetic Utility

Not typically applicable. This is an enzymatic activity assay kit intended for biochemical measurements rather than as a synthetic reagent or building block.

Guidance:

• For synthetic chemistry involving ester transformations, consider the Reaction & Applications and Reaction Conditions tabs only insofar as they inform handling and stability of ester substrates under aqueous/enzymatic conditions. Otherwise, select appropriate chemical reagents (e.g., acid/base catalysts, lipases) unrelated to this kit.

Target Specificity

Item-specific target details are not provided. Based on the product name, the kit measures total “liver esterase” activity in a sample rather than a single purified isoform.

General/literature context:

• Enzyme family: Carboxylesterases (CES), primarily CES1 and CES2 in human liver, along with other serine hydrolases exhibiting esterase activity.
• Substrate selectivity: Reporter substrates can display isoform bias (e.g., bulky acyl groups often favor CES1). The exact substrate used in this kit and its isoform preference are Not specified for this item; refer to the kit booklet.
• Specificity controls: Inclusion of a broad-spectrum esterase inhibitor (e.g., bis-p-nitrophenyl phosphate, BNPP) or selective inhibitors can help attribute measured activity to carboxylesterases vs other hydrolases. Heat-inactivation and no-substrate controls help define baseline signal.
• Sample specificity: The assay is suitable for liver-derived matrices; applicability to other tissues or species depends on isoform expression and should be confirmed empirically.

For definitive specificity claims (e.g., isoform-level resolution or lack of interference by cholinesterases), consult the kit’s validated interference testing, if provided in the CoA/Spec Sheet.

Foire aux questions

How should this product be stored?

Store at 2–8 °C, protected from light. The material is light-sensitive — keep it in its original opaque or amber container.

What does BioReagent mean?

BioReagent indicates that the product has been processed and tested for biological and biochemical applications. Specifications may include endotoxin limits, microbial controls, sterility, low DNase/RNase/protease activity, and verified biological activity where relevant.

How is this product shipped?

This product ships chilled on wet ice. Unpack on arrival and transfer it to the storage condition stated above.

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.