| Description | Catalase (CAT, EC 1.11.1.6) is widely found in animals, plants, microorganisms, and cultured cells. It is the primary H₂O₂-scavenging enzyme and plays a crucial role in the reactive oxygen species (ROS) scavenging system. H₂O₂ has a characteristic absorption peak at 240 nm. Catalase (CAT, EC 1.11.1.6) is widely found in animals, plants, microorganisms, and cultured cells. It is the primary H₂O₂-scavenging enzyme and plays a crucial role in the reactive oxygen species (ROS) scavenging system. H₂O₂ has a characteristic absorption peak at 240 nm. CAT decomposes H₂O₂, causing the absorbance of the reaction solution at 240 nm to decrease over time. The CAT activity can be calculated based on the rate of change in absorbance.Component50TStorageExtraction Buffer60 mL2-8℃Working Solution60 mL2-8℃User-Prepared Instruments and ReagentsUV spectrophotometer, benchtop centrifuge, adjustable pipettes, 1 mL quartz cuvette, mortar, ice, and distilled water.Experimental Procedure1. Crude Enzyme Extract Preparation1.1 Bacterial/Cell SamplesCollect bacteria or cells into a centrifuge tube, centrifuge, and discard the supernatant. Use a bacteria/cell count (10⁴) to Extraction Buffer volume (mL) ratio between 500:1 and 1000:1 (recommended: 5 million bacteria/cells in 1 mL Extraction Buffer). Disrupt the bacteria or cells by sonication (ice bath, power 20% or 200W, pulse 3s on, 10s off, repeat 30 times). Centrifuge at 8,000 g, 4°C for 10 minutes. Collect the supernatant and keep it on ice for assay.1.2 Tissue SamplesUse a tissue mass (g) to Extraction Buffer volume (mL) ratio between 1:5 and 1:10 (recommended: weigh approx. 0.1 g tissue, add 1 mL Extraction Buffer). Homogenize in an ice bath. Centrifuge at 8,000 g, 4°C for 10 minutes. Collect the supernatant and keep it on ice for assay.1.3 Serum (Plasma) SamplesAssay directly.2. Assay Steps2.1 Preheat the spectrophotometer for at least 30 minutes. Set the wavelength to 240 nm. Zero the instrument with distilled water.2.2 Before assay, incubate the CAT Working Solution in a water bath at 37°C (for mammals) or 25°C (for other species) for 10 minutes.2.3 Add 35 µL of sample and 1 mL of Working Solution into a 1 mL quartz cuvette. Mix well and immediately measure the initial absorbance at 240 nm (A₁). Measure the absorbance again after 1 minute (A₂). Calculate ΔA = A₁ - A₂.3. CAT Activity Calculation3.1 Calculation of CAT Activity in Serum (Plasma)Unit Definition: One unit of enzyme activity is defined as the amount that catalyzes the degradation of 1 nmol of H₂O₂ per minute per milliliter of serum (plasma).Derived Formula:CAT Activity (nmol/min/mL) = [ΔA × Vtotal reaction÷ (ε × d) × 10⁹] ÷ Vsample÷ TSimplified Formula:CAT Activity (nmol/min/mL) = 678 × ΔA3.2 Calculation of CAT Activity in Tissues, Bacteria, or Cells(1) Based on Sample Protein ConcentrationUnit Definition: One unit of enzyme activity is defined as the amount that catalyzes the degradation of 1 nmol of H₂O₂ per minute per milligram of tissue protein.Derived Formula:CAT Activity (nmol/min/mg prot) = [ΔA × Vtotal reaction÷ (ε × d) × 10⁹] ÷ (Vsample× Cpr) ÷ TSimplified Formula:CAT Activity (nmol/min/mg prot) = 678 × ΔA ÷ Cpr(2) Based on Sample Fresh WeightUnit Definition: One unit of enzyme activity is defined as the amount that catalyzes the degradation of 1 nmol of H₂O₂ per minute per gram of tissue.Derived Formula:CAT Activity (nmol/min/g fresh weight) = [ΔA × Vtotal reaction÷ (ε × d) × 10⁹] ÷ (W × Vsample÷ Vtotal sample) ÷ TSimplified Formula:CAT Activity (nmol/min/g fresh weight) = 678 × ΔA ÷ W(3) Based on Bacterial or Cell DensityUnit Definition: One unit of enzyme activity is defined as the amount that catalyzes the degradation of 1 nmol of H₂O₂ per minute per 10⁴ bacteria or cells.Derived Formula:CAT Activity (nmol/min/10⁴ cells) = [ΔA × Vtotal reaction÷ (ε × d) × 10⁹] ÷ (500 × Vsample÷ Vtotal sample) ÷ TSimplified Formula:CAT Activity (nmol/min/10⁴ cells) = 1.356 × ΔAParameter Definitions:1.ΔA: Change in absorbance (A₁ - A₂)2.Vtotal reaction: Total reaction volume (1.035 × 10⁻³ L)3.ε: Molar extinction coefficient of H₂O₂ (4.36 × 10⁴ L/mol/cm)4.d: Light path length of the cuvette (1 cm)5.10⁹: Unit conversion factor (1 mole = 10⁹ nmoles)6.Vsample: Volume of sample added to the reaction (0.035 mL)7.T: Reaction time (1 min)8.Cpr: Sample protein concentration (mg/mL)9.W: Sample weight (g)10.Vtotal sample: Total volume of extraction buffer added (1 mL)11.500: Total number of bacteria or cells (5 million)Precautions1.Before formal testing, it is essential to perform a preliminary test with 2-3 samples expected to have significant differences.2.This product is for research use only. Not for use in clinical diagnosis.Frequently Asked Questions (FAQ)Q: What should I do if I get a negative value?A: Check if bubbles formed during the reaction. Excessive bubbling indicates very high enzyme activity, and bubbles can interfere, causing negative values. Try diluting the sample 10-fold with Extraction Buffer and re-assaying. If no bubbles form (with diluted sample or original reaction) and a small negative value persists, it indicates that the enzyme activity in this sample is below the detection limit... Read More | When apoptosis occurs, some DNA endonucleases will be activated. These endonucleases will cut off genomic DNA between nucleosomes and produce 180 bp-200 BP DNA fragments, which appear as a specific ladder pattern in agarose gel electrophoresis. When double strand or single strand breaks occur in When apoptosis occurs, some DNA endonucleases will be activated. These endonucleases will cut off genomic DNA between nucleosomes and produce 180 bp-200 BP DNA fragments, which appear as a specific ladder pattern in agarose gel electrophoresis. When double strand or single strand breaks occur in genomic DNA, a large number of sticky 3'-oh ends will be generated, which can interact with YF under the catalysis of deoxyribonucleotide terminal transferase (TDT) ®/ CY dUTP binding can directly detect apoptotic cells by fluorescence microscopy or flow cytometry. This kind of method is called terminal deoxynucleotidyl transferase mediated nick end labeling (TUNEL). Because normal or proliferating cells have almost no DNA breaks, there is no 3'-oh formation and they can rarely be stained. TUNEL method can stain intact single apoptotic nuclei or apoptotic bodies in situ, can accurately reflect the typical biochemical and morphological characteristics of apoptosis, and can detect a very small number of apoptotic cells, so it is widely used in the study of apoptosis. This kit has a wide range of applications and can be used to detect apoptosis in frozen or paraffin sections, as well as cultured adherent cells or suspended cells. It can selectively detect apoptotic cells, but not necrotic cells or cells with DNA strand breaks caused by irradiation and drug treatment. This kit detects cell apoptosis with a short time-consuming, one-step staining reaction and can be detected after washing.Composition: Composition 20T 50T A. aladdin®640 TUNEL Reaction Buffer 1 mL 2 ×1.25 mL B. TdT Enzyme 20 µL 50 µL C. Proteinase K (2 mg/mL) 40 µL 100 µL D. DNase I (2 U/µL) 5 µL 13 µL E. 10 ×DNase I Buffer 100 µL 260 µL Product parameters：642/662 nm； Instruction： Experimental materials (self provided)PBS buffer (1 x, pH~7.4). 0.2% Triton X -100 (PBS formulation). 0.1% Triton X -100 (PBS formulation, containing 5 mg/mLBSA)4% paraformaldehyde (prepared with PBS)Immunohistochemical penDewaxing solvent (paraffin section sample)Related reagents for paraffin section processingAnti fluorescence quenching and sealing agent. ddH2Oexperimental design. A. Positive control:Prepare positive control slides using DNaseI treatment. DNaseI can digest single or double stranded DNA and expose the 3 '- OH end, artificially causing cell apoptosis. One experiment per time is sufficient. (To verify if there are any issues with the experimental operation and reagent kit)B. Negative control:Use TUNEL Reaction Buffer without TdT Enzyme and replace TdT Enzyme with ddH2O. (Mainly to exclude non-specific staining caused by cell apoptosis, operational processes, and other reasons; and to adjust the exposure intensity of the shooting.)C. Experimental processing group.The experimental group operated normally according to the instructions.D. Experimental control group.The experimental group operated normally according to the instructions.Experimental steps1. Sample preparation:(1) For adherent cells or cell smearsa. Clean once with PBS.Note: If you are concerned that the cells on the cell smear may not adhere firmly, you can dry the sample to make the cells adhere more firmly.b. Fixation: Add an appropriate amount of 4% paraformaldehyde (prepared with PBS) and fix at 4 ℃ for 30 minutes. Clean twice with PBS.c. Translucency: Add an appropriate amount of 0.2% Triton X -100 (prepared with PBS) and let it penetrate at room temperature for 20 minutes. Clean twice with PBS.d. Step 2: TUNEL reaction.(2) For suspended cells or cell suspensionsa. Collect cells (3-5 x 106 cells), centrifuge at 1000 rpm for 5 minutes, and wash twice with PBS.b. Fixation: Add an appropriate amount of 4% paraformaldehyde (prepared with PBS) and resuspend the cells thoroughly. Fix at 4 ℃ for 30 minutes. Centrifuge at 2000 rpm for 5 minutes and clean twice with PBS.c. Translucency: Add an appropriate amount of 0.2% Triton X -100 (prepared with PBS) and let it penetrate at room temperature for 20 minutes. Centrifuge at 2000 rpm for 5 minutes and clean twice with PBS.d. Step 2: TUNEL reaction.(3) Paraffin tissue sectioninga. Dewaxing and hydration: Place the sliced samples sequentially in xylene I (10 min) → xylene II (10 min) → 100% ethanol I (5 min) → 100% ethanol II (5 min) → 95% ethanol (5 min) → 90% ethanol (5 min) → 80% ethanol (5 min) → 70% ethanol (5 min) → ddH2O rinse for 5 min, rinse twice.Note: Xylene is toxic and volatile. Please perform this operation in a fume hood.b. Use filter paper to dry the liquid around the sliced sample, and circle the sample contour with an immunohistochemical pen for downstream transparency and labeling.Note: If it is found that the contour circle of immunohistochemistry strokes is damaged in subsequent experimental operations, it needs to be redrawn in a timely manner.c. Transparency: Dilute 2 mg/mL of ProteinaseK solution with PBS in a ratio of 1:100 to a final concentration of 20 µ g/mL. Add 100 µ L dropwise to each sample to cover all sample areas. Incubate at 20-37 ℃ for 20 minutes.Note: Protein K can penetrate the cell membrane and nuclear membrane, allowing subsequent staining reagents to fully enter the nucleus for reaction and improve labeling efficiency. An excessively long incubation time increases the risk of tissue slices falling off the carrier film during subsequent washing steps, while a too short incubation time may result in insufficient permeability treatment and affect labeling efficiency. To obtain better results, the concentration, incubation time, and temperature of Protein K need to be optimized according to different types of tissue samples.d. Wash the slices twice with PBS, each time for 5 minutes. Use filter paper to remove excess liquid, and place the processed sample in a wet box to keep it moist.Note: Protein K must be washed thoroughly in this step, otherwise it will seriously interfere with subsequent labeling reactions.e. Step 2: TUNEL reaction.(4) Frozen tissue sectionsa. Fixation: Take out frozen sections and warm them back to room temperature. Add an appropriate amount of 4% paraformaldehyde (prepared with PBS) and fix at room temperature for 30 minutes. Wash twice with PBS for 10 minutes each time.Note: If you are concerned that formaldehyde cleaning may not be clean enough, it may affect the final dyeing effect. After formaldehyde fixation is completed, an appropriate amount of 2 mg/mL glycine can be added and washed for 10 minutes to neutralize the residual fixing solution, and then PBS cleaning can be carried out.b. Use filter paper to dry the liquid around the sliced sample, and circle the sample contour with an immunohistochemical pen for downstream transparency and labeling.Note: If it is found that the contour circle of immunohistochemistry strokes is damaged in subsequent experimental operations, it needs to be redrawn in a timely manner.c. Transparency: Dilute 2 mg/mL of ProteinaseK solution with PBS in a ratio of 1:100 to a final concentration of 20 µ g/mL. Add 100 µ L dropwise to each sample to cover all sample areas. Incubate at 20-37 ℃ for 20 minutes.Note: Protein K can penetrate the cell membrane and nuclear membrane, allowing subsequent staining reagents to fully enter the nucleus for reaction and improve labeling efficiency. An excessively long incubation time increases the risk of tissue slices falling off the carrier film during subsequent washing steps, while a too short incubation time may result in insufficient permeability treatment and affect labeling efficiency. To obtain better results, the concentration, incubation time, and temperature of Protein K need to be optimized according to different types of tissue samples.d. Wash the slices twice with PBS, each time for 5 minutes. Use filter paper to remove excess liquid, and place the processed sample in a wet box to keep it moist.Note: Protein K must be washed thoroughly in this step, otherwise it will seriously interfere with subsequent labeling reactions.e. Step 2: TUNEL reaction.(5) Positive treatment (only the positive control is subjected to this step, and other samples are directly subjected to the TUNEL reaction step)a. Dilute 10 x DNase I Buffer with ddH2O in a ratio of 1:10 to 1 x DNase I Buffer for later use.b. Drip 100 µ L of 1xDNase I Buffer onto the processed sample, covering all sample areas, and equilibrate at room temperature for 5 minutes.c. Dilute DNase I (2 U) with 1 x DNase I Buffer at a ratio of 1:100/ µ L) A working solution with a final concentration of 20 U/mL.d. Discard the buffer and add 100 µ Incubate DNase I working solution with a concentration of 20 U/mL at room temperature for 10 minutes.e. Discard DNase I working solution and clean twice with PBS.f. Step 2: TUNEL reaction.2. TUNEL reaction(1) Prepare TUNEL reaction solution (ready to use): / 1 sample 5 sample 10 sample TdT enzyme 1 µL 5 µL 10 µL YF®488/555/594/640 TUNEL Reaction Buffer 49 µL 245 µL 490 µL TUNEL Total volume of reaction solution 50 µL 250 µL 500 µL (2) For adherent cells, cell smears, or tissue sectionsa. Add 50 to each sample µ L TUNEL reaction solution, evenly cover the sample with the reaction solution. The appropriate time for dark incubation at 37 ℃ (recommended staining time for cells is 30 minutes to 1 hour, and tissue staining time is 2 hours).Note: 50 µ L TUNEL reaction solution is suitable for smear, slicing, or 96 well plates (other different well plates can adjust the volume of TUNEL reaction solution appropriately to cover cells). If the sample to be tested is a smear, slice, or in a 24 well plate, 12 well plate, or 6 well plate, anti evaporation film can be used, or self sealing bags or other appropriate materials can be used to cut circular plastic sheets slightly smaller than the holes. After adding TUNEL reaction solution dropwise, cover the sample to prevent the evaporation of TUNEL reaction solution and make the TUNEL reaction solution evenly cover the sample.b. Discard the TUNEL reaction solution, wash twice with PBS, and then wash three times with 0.1% Triton X -100 (PBS preparation, containing 5 mg/mL BSA) for 5 minutes each time. This way, free unreacted markers can be removed cleanly.c. (Optional) Add an appropriate concentration of 5 to each sample µ DAPI staining solution with a concentration of g/mL, incubated at room temperature in dark for 5 minutes. After staining, discard DAPI staining solution and wash twice with PBS for 5 minutes each time.d. (Optional) Slice sealing: Add 50 drops to each sample µ L anti fluorescence quenching sealing agent (anti fluorescence quenching sealing agent may not be suitable for certain dyes, it is recommended to conduct pre experimental testing for compatibility before the experiment), cover the cover glass, gently tap the cover glass with the blunt end of tweezers to remove bubbles and ensure complete sealing.e. Use filter paper to remove excess liquid and add 100 to the sample area µ Keep the sample moist with PBS and immediately observe under a fluorescence microscope.(3) For suspended cells or cell suspensionsa. Add 50 to each sample tube µ Gently resuspend cells in LTUNEL reaction solution and incubate at 37 ℃ in the dark for 30-1 hour. Gently resuspend cells with a micropipette every 15 minutes.b. Centrifuge at 2000 rpm for 5 minutes, discard TUNEL reaction solution, and wash twice with 0.1% Triton X -100 (PBS preparation, containing 5 mg/mLBSA) for 5 minutes each time. This way, free unreacted markers can be removed cleanly.c. Add 100 to each sample tube µ L concentration is 5 µ DAPI staining solution with a concentration of g/mL, incubated at room temperature in dark for 5 minutes.d. Join 400 µ L PBS resuspended cells and immediately detected with a flow cytometer or observed under a fluorescence microscope after smearing.Matters needing attention：1. please centrifuge the product to the bottom of the tube immediately before use, and then conduct subsequent experiments. 2. when the staining background is heavy or non-specific staining is obvious, the staining time can be appropriately reduced. 3. it is recommended to add negative control and positive control groups during the experiment. 4. please wear mask and gloves when using component A. if it contacts the skin, please wash it with plenty of water immediately. 5. fluorescent dyes have quenching problems. Please try to avoid light to slow down fluorescence quenching. 6. for your safety and health, please wear experimental clothes and disposable gloves.Scope of application：Late apoptosis detection, TUNEL Kit... Read More | Hydrogen peroxide, a reactive oxygen species produced through the metabolism of molecular oxygen, serves as both an intracellular signaling messenger and a source of oxidative stress. Hydrogen peroxide is generated in cells via multiple mechanisms such as the NOX-mediated ROS production by Hydrogen peroxide, a reactive oxygen species produced through the metabolism of molecular oxygen, serves as both an intracellular signaling messenger and a source of oxidative stress. Hydrogen peroxide is generated in cells via multiple mechanisms such as the NOX-mediated ROS production by neutrophils and macrophages (respiratory burst) or by the dismutase of superoxide anions produced as a result of electron leak during mitochondrial respiration. Abnormal hydrogen peroxide production contributes to oxidative cell damage and the progression of diseases such as asthma, atherosclerosis, osteoporosis, and neurodegeneration.Intracellular hydrogen peroxide assay kit has been used to measure intracellular hydrogen peroxide levels... Read More | Inquire | Product introduction：Reporter gene detection is an important tool for analyzing the interaction between potential cis elements (such as promoters, enhancers and silencers) and trans acting factors in the flanking region of structural genes in the field of modern molecular biology. Firefly Product introduction：Reporter gene detection is an important tool for analyzing the interaction between potential cis elements (such as promoters, enhancers and silencers) and trans acting factors in the flanking region of structural genes in the field of modern molecular biology. Firefly luciferase is widely used in gene regulation and drug screening. Firefly luciferase is a protein with a molecular weight of about 61 KD. In the presence of ATP, magnesium ions and oxygen, it can catalyze the production of oxyluciferin from luciferin. In the process of luciferin oxidation, it will produce a light signal. The optical signal of this kit is a kind of instantaneous light, which needs to be detected immediately after adding the working solution. The half-life of optical signal is about 5 min.Instruction：1.Working fluid configuration ( 1 ) Restore all components to room temperature. ( 2 ) The component B ( stock solution ) was fully diluted with component A to prepare a 0.2 mg / mL firefly luciferase working solution, which was vortexed and shaken to ensure full mixing. Note : The firefly luciferase working solution cannot be repeatedly frozen and thawed. If the dosage of a single experiment is small, it is recommended to subpackage according to a single dosage. At room temperature, the activity decreased by about 10 % after the working solution was configured for 3 h, and the activity decreased by about 25 % after 5 h. 2.chemiluminescence value detection ( 1 ) The cell culture plate was taken out from the incubator and incubated at room temperature for 20 min to restore it to room temperature ( 22-25 ° C ). ( 2 ) Add the same volume of firefly luciferase working solution with the medium to the culture plate and mix well. ( 3 ) Incubation at room temperature for 5 min. Note : The incubation time can be adjusted according to cell type and cell number. ( 4 ) The values were read by multifunctional microplate reader or chemiluminescence instrument ( instrument parameters : the determination time was 10 s, the determination interval was 2 s ).Matters needing attention：1. please centrifuge the product to the bottom of the tube immediately before use, and then conduct subsequent experiments. 2. the strongest wavelength of bioluminescence catalyzed by firefly luciferase is 560 nm. 3. to prevent interference between holes, it is recommended to use white opaque orifice plate.Recommendation：Component B is recommended to use sterile water in advance to configure 2 mg / mL storage solution, A component and B component configured as storage solution, and small batch packaging according to the experimental requirements. The detection working fluid is recommended to be used now to avoid repeated freezing and thawing. Component：One-Step Firefly Luciferase Assay Buffer；D-Luciferin Scope of application：Mainly used for ADCC detection... Read More |