| Description | Lactate dehydrogenase (LDH or LD) is a stable protein present in the cytoplasm of normal cells and normally cannot pass through the cell membrane. When cells are damaged, membrane permeability increases, and LDH is released extracellularly. A decrease in intracellular LDH and an increase in LDH in Lactate dehydrogenase (LDH or LD) is a stable protein present in the cytoplasm of normal cells and normally cannot pass through the cell membrane. When cells are damaged, membrane permeability increases, and LDH is released extracellularly. A decrease in intracellular LDH and an increase in LDH in the culture medium occur. Measuring the LDH activity in the culture medium or the LDH leakage rate can reflect drug-induced cytotoxicity. LDH belongs to the oxidoreductase family and can reversibly catalyze the redox reaction between lactate (L) and pyruvate (P). The reaction formula is: Lactate + NAD⁺ → Pyruvate + NADH + H⁺, where L → P is the forward reaction and P → L is the reverse reaction. Detection Principle: Using NAD⁺ as a hydrogen acceptor, LDH catalyzes the dehydrogenation of lactate to generate pyruvate. Pyruvate then reacts with dinitrophenylhydrazine to form pyruvate dinitrophenylhydrazone, which appears brownish-red in an alkaline solution. The color intensity is proportional to the pyruvate concentration. The absorbance at 440 nm can be measured using a microplate reader. The released LDH activity during cytotoxicity or the LDH activity in other samples can be calculated using formulas. This kit can be used for routine LDH activity detection and is more commonly used for cytotoxicity assays using LDH release as an indicator.This kit is for scientific research use only and is not intended for clinical diagnosis or other purposes.L1501786Component100T500TStorageL1501786ALDH Assay Buffer3 mL15 mL2-8℃. Store in the dark.L1501786BNAD1EA2EA-20℃L1501786CPhenylhydrazine Color Solution3 mL15 mL2-8℃. Store in the dark.L1501786DAlkaline Color Solution10 mL50 mLRT.L1501786ELDH Releasing Agent (10X)2 mL10 mLRT.User-Prepared Instruments and Reagents1. 96-well plate cultured test and control group cell samples, sterile PBS, culture medium, distilled water.2. Microplate centrifuge, 96-well plate or centrifuge, centrifuge tubes, incubator or water bath, microplate reader.Experimental Procedure1. Sample Preparation1.1 LDH Release AssaySeed an appropriate number of cells into a 96-well culture plate based on cell size and growth rate, so that the cell density does not exceed 90% confluency at the time of detection.Aspirate the culture medium, wash once with PBS, add fresh culture medium.Set up corresponding control groups according to experimental needs:Background Blank Control Well A: Culture medium without cells.Sample Control Well B: Control cells without drug treatment.Maximum Enzyme Activity Control Well C: Lysed samples from untreated cells.Drug-treated Sample Well D: Cells treated with the drug.Continue cultivation.Before detection, take out the cell culture plate. Add LDH Releasing Agent (10X) to the "Maximum Enzyme Activity Control Well C" at a volume equal to 10% of the original culture medium volume. Mix thoroughly by pipetting up and down several times. Continue cultivation for about 1 hour.Centrifuge the cell culture plate at 400 g for 5 minutes using a microplate centrifuge.Aspirate 5 µL of supernatant from each well and transfer it to the corresponding wells of a new 96-well plate for subsequent LDH detection.1.2 Cytotoxicity and Cell Proliferation Assay for Intracellular Total LDHSeed an appropriate number of cells into a 96-well culture plate based on cell size and growth rate, so that the cell density does not exceed 90% confluency at the time of detection.Treat with different drugs and set up appropriate controls.Centrifuge the cell culture plate at 400 g for 5 minutes using a microplate centrifuge.Aspirate the culture medium.Add 150 µL of LDH Releasing Agent diluted 10-fold with PBS. Shake the plate to mix thoroughly. Continue cultivation for about 1 hour.Centrifuge the cell culture plate at 400 g for 5 minutes using a microplate centrifuge.Aspirate 5 µL of supernatant from each well and transfer it to the corresponding wells of a new 96-well plate for subsequent cytotoxicity detection.1.3 Protein Concentration DeterminationAfter sample preparation, the protein concentration can be determined using a BCA Protein Assay Kit (Aladdin B665595 BCA Protein Quantification Kit or R1491648 Ready-to-Use BCA Protein Quantification Kit are recommended) to facilitate subsequent calculation of LDH content per unit protein weight in tissues or cells.2. Preparation of NAD SolutionTake one vial of NAD (powder) and dissolve it in 1.5 mL of deionized water.3. LDH Enzymatic ReactionAdd solutions sequentially according to the table below, taking care to avoid bubbles. If the enzyme activity in the sample is too high, reduce the sample volume or dilute appropriately before assay.Reagent (µL)Volume (µL)Test Sample (supernatant)5LDH Assay Buffer25NAD Solution5 Mix well, incubate at 37°C for 15 min. Phenylhydrazine Color Solution25 Mix well, incubate at 37°C for 15 min. Alkaline Color Solution100Distilled Water150 4. LDH Measurement Mix well and let stand at room temperature for 5 minutes. Measure the absorbance of each well at 440 nm using a microplate reader. 5. Result Calculation Cytotoxicity or Mortality Rate (%) = (A D - A B ) / (A C - A B ) × 100% If the absorbance value A γ of a known concentration *c* of an LDH enzyme standard and the absorbance value A γ0 of the standard blank control are measured simultaneously, the enzyme activity in the sample can be roughly calculated:LDH Activity in Test Sample (mU/mL) = (A B - A A ) / (A γ - A γ0 ) × *c* For accurate calculation of the absolute LDH enzyme activity in the sample, use a self-prepared LDH standard to plot a standard curve with the measured absorbance values. The enzyme activity of the sample can be calculated using the formula derived from the standard curve. Where: A A = Absorbance of Background Blank Control Well A A B = Absorbance of Sample Control Well B A C = Absorbance of Maximum Enzyme Activity Control Well C A D = Absorbance of Drug-treated Sample Well D 6. Results and Analysis The cytotoxicity of drugs or toxicants can be determined by directly comparing the LDH activity in each well. Higher LDH activity indicates higher cell membrane permeability and more severe cell damage.Precautions1. Use serum-free or low-serum concentration culture medium when culturing cells to exclude serum interference; otherwise, deviations may occur.2. EDTA inhibits LDH. Avoid using or thoroughly remove reagents containing EDTA during operation.3. Measure LDH as soon as possible after collection. If the collected cell culture medium is stored for too long, LDH activity may decrease.4. Use solutions prepared at the same time for the same batch of experiments. The volume of solutions used and the reaction time should be consistent.5. In the enzymatic reaction, the recommended supernatant sample volume is 2.5-10 µL. If the enzyme activity in the sample is too high, reduce the sample volume or dilute appropriately before assay.6. Measurement should be completed within 15 minutes after color development.7. The Alkaline Color Solution is somewhat corrosive; handle with care.8. Use reagents promptly after opening to avoid affecting subsequent experimental results.9. For your safety and health, please wear a lab coat and disposable gloves during operation... Read More | Products content Box 1: Circularization reagentC666001Component16 TStorageC666001ASplint Oligo20 µL-20℃.Avoid freeze/thaw cycle. C666001B5×Splint Buffer T4250 µL-20℃.Avoid freeze/thaw cycle. C666001CDNA Ligase50 µL-20℃.Avoid freeze/thaw cycle. C666001DDigestion Products content Box 1: Circularization reagentC666001Component16 TStorageC666001ASplint Oligo20 µL-20℃.Avoid freeze/thaw cycle. C666001B5×Splint Buffer T4250 µL-20℃.Avoid freeze/thaw cycle. C666001CDNA Ligase50 µL-20℃.Avoid freeze/thaw cycle. C666001DDigestion Buffer20 µL-20℃.Avoid freeze/thaw cycle. C666001EDigestion Enzyme I70 µL-20℃.Avoid freeze/thaw cycle. C666001FDigestion Enzyme III25 µL-20℃.Avoid freeze/thaw cycle. Box 2: Magnetic Beads for DNA Purification and RecoveryC666001Component16 TStorageC666001GCMPure4×1.5 mL2-8℃Products IntroductionThe Cyclization Kit is a modular kit tailored for the MGI high-throughput sequencing platform. With this kit, PCR products after junction ligation can be prepared into single-stranded circular DNA libraries suitable for MGI sequencers. All reagents provided in the kit have been subjected to stringent quality control and functional validation to maximize the stability and reproducibility of library construction. Provide your own instruments, reagents and consumables1. Magnetic frame: DynaMagTM-2 (Cat. No. 12321D) is recommended.2. "Qubit" 3.0 Fluorescence Quantimeter (ThermoFisher, Cat. No. Q33216)3. Qubit" ssDNA Assay Kit (Invitrogen, Cat. No. Q10212)4. Anhydrous ethanol, EB (10 mM Tris-HCl, pH 8.0), NF Water (pH between 7.0 and 8.0).5. reaction tubes: low adsorption PCR tubes with 1.5 mIEP tubes are recommended: 5.Tip: It is recommended to use a high quality filter tip to prevent contamination of kits and libraries. Pre-experiment Preparation and Important Notes 1. Sample preparation.PCR product: 2330 ng total (total amount when multiple PCR products are mixed) in a volume of 49 pL (if the volume of PCR product is insufficient, add NF Water to bring the total volume to 49 pl). -PCR product: Fragment size: The fragment peak is between 200-500 bp. -PCR product fragment size: Fragment peaks between 200-500 bp. -PCR product modification: Fixed sequences (with Index) for MGISEQ-2000, MGISEQ-200 and BGISEQ-500 sequencing platforms were added.2. Reagent preparation-Remove the corresponding reagents from the kit, centrifuge briefly, and place the enzyme mixture on ice until ready to use: buffers need to be dissolved at room temperature before use, then centrifuged with shaking and placed on ice until ready to use, and NF Water and EB are placed at room temperature until ready to use: "Please make up the mixture on ice:Precipitation may appear after the buffer in the kit is dissolved, the precipitation does not affect the function of the reagent, please shake and mix well until the precipitation disappears and then use. Schematic diagram of the cyclization process procedurecyclize 1. 1 wl of Splint Oligo was added to the 49JI PCR product. The product was denatured and incubated on a PCR instrument at 95°C for 3 min, then immediately transferred to an ice bath and allowed to stand for 2 min. 2. The reaction mixture was prepared on ice according to the following system. 3. Add 15ul of the above reaction mixture to 50µl of denatured DNA.4. Place the above PCR tubes on the PCR instrument under the following conditions Reaction. digest 1. Prepare the digestion reaction solution on ice according to the following system. 2. After the cyclization reaction, add 8l of digestion reaction solution directly to the cyclization system, mix well, centrifuge briefly and then place the PCR tube on the PCR instrument and react under the following conditions. 3. Purification was carried out immediately after the reaction.Purification of digestive products1. Remove CMPure at room temperature 30 minutes prior to use and mix well with shaking.2. Transfer the digested product to a 1.5 mIEP tube, pipette 340 pICMPure into the digested product, mix well by gently blowing 10 times with a pipette and incubate for 10 minutes at room temperature.3. Instantaneous centrifugation, place the EP tube on a magnetic rack and let stand for 5 minutes until the liquid is clear, pipette and discard the supernatant.4. Keep the EP tube fixed on a magnetic rack, add 250ul of freshly prepared 80% ethanol, let it stand at room temperature for 1 minute, then carefully discard the supernatant.5. Repeat step 4 once, try to suck up the liquid at the bottom of the tube: Note: Do not suck up the magnetic beads, so as not to affect the yield.6. Keep the EP tube fixed on the magnetic rack, open the cap and dry it at room temperature for 5-10 minutes.7. Remove the EP tube from the magnetic rack, add 35ul of EB or NF Water for DNA elution, pipette blow to mix and dissolve at room temperature for 10 min.8. Centrifuge instantaneously, place the EP tube on a magnetic rack and let stand for 2 minutes until the liquid is clarified, transfer the supernatant to a new EP tube. -Store at 20C and leave to prepare DNB... Read More | The content of this cell is too long for an XLSX file (more than 32767 characters). Please use the CSV format for this export | DescriptionProvides an inert environment to run oxygen sensitive cross-coupling reactions in a laboratory fume hood.Designed to be used with KitAlysis High-Throughput Screening Kits and KitAlysis 24-Well Reaction Block | Inquire |