| Description | Phosphoenolpyruvate Carboxykinase (PEPCK, EC 4.1.1.32) is widely present in animals, plants, microorganisms, and cells. It catalyzes the conversion of oxaloacetate to phosphoenolpyruvate and is a key regulatory enzyme in the gluconeogenesis pathway.Assay PrinciplePEPCK catalyzes the conversion of Phosphoenolpyruvate Carboxykinase (PEPCK, EC 4.1.1.32) is widely present in animals, plants, microorganisms, and cells. It catalyzes the conversion of oxaloacetate to phosphoenolpyruvate and is a key regulatory enzyme in the gluconeogenesis pathway.Assay PrinciplePEPCK catalyzes the conversion of Oxaloacetate to Phosphoenolpyruvate and CO₂. Pyruvate Kinase and Lactate Dehydrogenase subsequently catalyze the sequential oxidation of NADH to NAD⁺. The rate of decrease in NADH absorbance at 340 nm is measured, which reflects PEPCK activity.Component50TStorageAcidic Extraction Buffer60 mL2-8℃Reagent 145 mL2-8℃Reagent 241 µL2-8℃Reagent 31EA-20℃Reagent 41EA-20℃Required Materials and Equipment (Not Provided)UV spectrophotometer, benchtop centrifuge, adjustable pipettes, 1 ml quartz cuvette, mortar and pestle, ice, and distilled water.Sample Preparation:*Note: The provided sample-to-buffer ratios (1:1, w/v or based on cell count) using microliters (µl) are highly unusual and likely a typo in the original text. Standard protocols use milliliters (ml). The calculations also imply ml. The following protocol assumes the intended volumes are in milliliters (ml).*Bacteria or Cultured Cells:Collect cells by centrifugation and discard the supernatant.Add Acidic Extraction Buffer at a ratio of 1 ml per 5-10 million cells (e.g., 1 ml for 5 million cells).Sonicate on ice (20% power or 200W, pulse 3s on/10s off, repeat 30 times).Centrifuge at 8000 g, 4°C for 10 min. Collect the supernatant and keep it on ice for assay.Tissues:Homogenize tissue on ice in Acidic Extraction Buffer at a ratio of 1:5-10 (w/v) (e.g., 0.1 g tissue in 1 ml buffer).Centrifuge at 8000 g, 4°C for 10 min. Collect the supernatant and keep it on ice for assay.Serum (or Plasma) Samples:Assay directly.Assay Procedure:Preheat the spectrophotometer for at least 30 minutes. Set the wavelength to 340 nm. Zero the instrument with distilled water.Preparation of Working Solution: Just before use, transfer and dissolve Reagent 2 and Reagent 3 into Reagent 1. Mix well. Aliquot and store any unused portions at -20°C. Avoid repeated freeze-thaw cycles.Preparation of Reagent 4: Just before use, dissolve the contents of the vial in 2.5 mL of distilled water. Mix well. Aliquot and store any unused portions at -20°C. Avoid repeated freeze-thaw cycles.Pre-warm the Working Solution and dissolved Reagent 4 at 37°C (for mammalian samples) or 25°C (for other species) for 5 minutes.In a 1 ml quartz cuvette, add:50 µl sample50 µl dissolved Reagent 4900 µl pre-warmed Working SolutionMix immediately and record the initial absorbance (A₁) at 340 nm. Record the absorbance again (A₂) after exactly 1 minute. Calculate ΔA = A₁ - A₂.Note: For this kit, if ΔA is greater than 0.1, dilute the sample with Acidic Extraction Buffer by an appropriate factor (account for this dilution factor 'n' in the calculations) so that ΔA is less than 0.1 to improve detection sensitivity.PEPCK Activity Calculation:General Parameters for 1 ml Cuvette (d = 1.0 cm):Vₜₒₜₐₗ (Total reaction volume) = 0.001 L (1000 µL)ε (NADH molar extinction coefficient) = 6220 L/mol/cmd (Cuvette light path) = 1.0 cmVₛₐₘₚₗₑ (Sample volume in reaction) = 0.05 mL (50 µL) [Note: Corrected from 0.05µL, which is implausible]T (Reaction time) = 1 minVₛₐₘₚₗₑₜₒₜₐₗ (Total extract volume) = 1 mL (for tissues/cells) [Note: Corrected from 1µL]Cpr (Sample protein concentration, mg/mL) [Note: Corrected from mg/µL]W (Sample mass, g)500 (Cell/Bacteria count in millions for example calculation: 5 million)1. For Serum (Plasma):Definition: One unit of activity is defined as the amount of enzyme that consumes 1 nmol of NADH per minute per ml of serum.Calculation:PEPCK Activity (nmol/min/ml) = [ΔA × Vₜₒₜₐₗ ÷ (ε × d) × 10⁹] ÷ Vₛₐₘₚₗₑ ÷ TSimplified Formula: PEPCK (nmol/min/ml) = 3215 × ΔA2. For Tissues, Bacteria, or Cells:Based on Sample Protein Concentration:Definition: One unit of activity is defined as the amount of enzyme that consumes 1 nmol of NADH per minute per mg of protein.Calculation:PEPCK Activity (nmol/min/mg prot) = [ΔA × Vₜₒₜₐₗ ÷ (ε × d) × 10⁹] ÷ (Vₛₐₘₚₗₑ × Cpr) ÷ TSimplified Formula: PEPCK (nmol/min/mg prot) = 3215 × ΔA ÷ CprBased on Sample Fresh Weight:Definition: One unit of activity is defined as the amount of enzyme that consumes 1 nmol of NADH per minute per gram of fresh tissue.Calculation:PEPCK Activity (nmol/min/g fresh weight) = [ΔA × Vₜₒₜₐₗ ÷ (ε × d) × 10⁹] ÷ (W × Vₛₐₘₚₗₑ / Vₛₐₘₚₗₑₜₒₜₐₗ) ÷ TSimplified Formula: PEPCK (nmol/min/g fresh weight) = 3215 × ΔA ÷ WBased on Bacterial or Cell Density:Definition: One unit of activity is defined as the amount of enzyme that consumes 1 nmol of NADH per minute per 10⁴ cells.Calculation (example for 5 million cells in 1 ml extract):PEPCK Activity (nmol/min/10⁴ cell) = [ΔA × Vₜₒₜₐₗ ÷ (ε × d) × 10⁹] ÷ (500 × Vₛₐₘₚₗₑ / Vₛₐₘₚₗₑₜₒₜₐₗ) ÷ TSimplified Formula: PEPCK (nmol/min/10⁴ cell) = 6.43 × ΔAPrecautionsBefore formal assay, it is essential to perform a pilot test with 2-3 samples expected to have significant differences in activity... Read More | The bacterial viability / toxicity detection kit contains two fluorescent dyes. Nucgreen is a green nucleic acid dye that can stain live and dead bacteria; Ethd III is a red nucleic acid dye that only stains dead bacteria with damaged cell membranes. When nucgreen and ethd III are properly mixed, The bacterial viability / toxicity detection kit contains two fluorescent dyes. Nucgreen is a green nucleic acid dye that can stain live and dead bacteria; Ethd III is a red nucleic acid dye that only stains dead bacteria with damaged cell membranes. When nucgreen and ethd III are properly mixed, the bacteria with intact cell membrane appear green, while the bacteria with damaged cell membrane can appear green and red under different channels, respectively. A common criterion for bacterial viability is the ability to propagate in a suitable nutrient medium, known as a growth assay. This kit is generally in good agreement with the growth assay results in liquid or solid medium. However, under certain conditions, membrane damaged bacteria may recover and propagate in nutrient medium, and such bacteria will be identified as dead bacteria in this assay. On the contrary, some bacteria with intact membranes may not be able to propagate in nutrient medium, but will be recognized as viable bacteria in this assay. Therefore, if there is a large difference between the test results of this kit and the bacterial growth assay, the above possibilities should be considered. Component： Product parameters： NucGreen: Ex/Em = 503/530 nm (结合 DNA)；EthD-III: Ex/Em = 530/620 nm (结合 DNA)。Usage:1 Preparation of control samples for live and dead bacteria (optional)1. Cultivate 4 mL of bacteria in liquid medium until late logarithmic phase.2. Prepare two 1 mL bacterial solutions in an EP tube and centrifuge for 10-15 minutes under 5000-10000 g conditions.3. Remove the supernatant and add 0.3 mL of 0.85% NaCl resuspended bacteria to one of the EP tubes, and 1 mL of 0.85% NaCl resuspended bacteria to the other tube.4. Add 0.7 mL of isopropanol to a tube containing 0.3 mL of 0.85% NaCl, and mix thoroughly (with a final concentration of 70% isopropanol) to prepare a dead bacterial sample.5. Incubate the two samples at room temperature for 1 hour and mix every 15 minutes.6. Centrifuge the two samples at 5000-10000 g for 10-15 minutes.7. Remove the supernatant, add 1 mL of 0.85% NaCl to resuspend the bacteria in both samples, and centrifuge again as in step 6.8. Use a spectrophotometer to measure the absorbance values (OD670) of two bacterial suspensions at 670 nm.9. Adjust the density of the two bacterial suspensions (live and dead) to 108 bacteria/mL (OD670 ≈ 0.3), and then dilute with 0.85% NaCl at 1:100 to achieve a final density of 106 bacteria/mL.10. Mix two bacterial suspensions as shown in the table below to obtain the required live cell ratio: dead cell ratio.Table 1 Mix live and dead bacterial suspensions by a certain volume to achieve the required ratio of live and dead cellsLive cells: Dead cellsVolume of viable bacterial suspension（mL）Volume of dead bacterial suspension（mL）0:10001.010:900.10.920:800.20.830:700.30.750:500.50.5100:01.00II Staining methods for fluorescence microscopy observation1. Mix 1 volume of component A, NucGreen, and 2 volumes of component B, EthD-III, in a microcentrifuge tube. After thorough mixing, add 8 volumes of 0.85% NaCl solution to obtain a 100 x dye solution.2. Every 100 µ L bacterial suspension, add 1 µ 100 x dye solution of L.3. Mix thoroughly and incubate at room temperature in the dark for 15 minutes.4. Take 5 µ The bacterial suspension after L staining was dropped onto a glass slide with an 18 mm square cover glass.5. Observe under a fluorescence microscope. The fluorescence of live and dead bacteria can be observed simultaneously under any standard FITC long-acting filter. Alternatively, live (green fluorescent) and dead (red fluorescent) bacteria can be observed using FITC and Cy3 (or Texas Red) channels, respectively.Attention: (1) Before staining bacteria, attention must be paid to removing residues of growth media. Nucleic acid and other media components can bind to NucGreen and EthD-III dyes in some way, resulting in unacceptable staining changes. A simple washing step is usually sufficient to remove interfering media components from bacterial suspension. It is not recommended to use phosphate buffer solutions as they can reduce staining efficiency. (2) Before starting the formal experiment, the dye concentration should be adjusted to distinguish between NucGreen labeling live bacteria and EthD-III labeling dead bacteria. The optimal concentration may vary depending on the bacterial strain. It is generally best to use the lowest dye concentration that can provide sufficient signal. The above conditions have been optimized for staining live/dead cells of Escherichia coli.III Before starting the staining method experiment of flow cytometry, please read the precautions under the fluorescence microscope staining steps.According to Table 1, add 11 different proportions of live and dead bacteria to the EP tube. Each of the 11 samples has a volume of 1 mL.2. Add 12 µ The A component of L, NucGreen, and 24 µ The B component EthD-III of L was mixed in a microcentrifuge tube. Add 3 to each of the 11 samples µ Mix the mixed dyes of L thoroughly by blowing them up and down several times. (Note: Additional control bacterial samples need to be prepared for separate NucGreen and EthD-III staining)3. Incubate at room temperature in the dark for 15 minutes.4. Analyze each sample using a flow cytometer, detect NucGreen positive cells using FITC channels, and detect EthD-III positive cells using PI or PE channels.Matters needing attention：1. please centrifuge the product to the bottom of the tube immediately before use, and then conduct subsequent experiments. 2. if the orifice plate is used for detection, a small amount of bacterial liquid can be left for imaging after standing for 10 min, which can effectively reduce the background. 3. in order to be closer to the real results, it is recommended to keep the brightness of red fluorescence consistent with that of green fluorescence in merge pictures. 4. fluorescent dyes have quenching problems. Please try to avoid light during experimental operation to slow down fluorescence quenching. 5. for your safety and health, please wear experimental clothes and disposable gloves.Scope of application：Staining of dead and live bacteria... 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 | This product can rapidly, gently, and efficiently lyse mammalian cells, effectively extracting cytoplasmic and nuclear proteins. This reagent uses a mild formula to ensure that the extracted protein maintains biological activity and can be applied to various protein analysis experiments, such as This product can rapidly, gently, and efficiently lyse mammalian cells, effectively extracting cytoplasmic and nuclear proteins. This reagent uses a mild formula to ensure that the extracted protein maintains biological activity and can be applied to various protein analysis experiments, such as reporter gene and enzyme activity determination, immune detection, protein purification, etc. The extracted protein can be quantitatively analyzed using the BCA method. The reagent kit contains a mixture of protease inhibitors, which can effectively prevent protein degradation during the protein extraction process.M665813Component100 TStorageM665813AMammalian Protein Extraction Reagent100 mLRTM665813BProtease Inhibitor Cocktail (100×)1 mL-20℃. Avoid freeze/thaw cycle. precautions1. This product can effectively lyse adherent cells cultured on cell culture plates (without scraping) and suspended cells collected by centrifugation, with higher extraction efficiency than repeated freeze-thaw or ultrasound methods. But for the extraction of tissue proteins, it is recommended to use the tissue protein extraction kit (CW0891).The optimal dosage for protein extraction from adherent cells is listed in Table 1. Collecting cells first can reduce the amount of reagents used to obtain higher protein concentrations.3. The amount of extraction reagents used can also be estimated based on the number of cells. If 2 × 106 Hela cells weigh about 20 mg, 200 need to be added µ Extract reagents.4. The protein extracted from this product can be quantitatively analyzed using the BCA method.Operation steps● Protein extraction from adherent cells1. Please remove the required Mammalian Protein Extraction Agent for pre cooling before protein extraction.2. Carefully pour out the culture medium of adherent cells and rinse the cells with PBS.3. Add an appropriate amount of Mammalian Protein Extraction Reagent (add Protein Inhibitor Cocktail in a 1:99 ratio 2-3 minutes before protein extraction), blow adherent cells on ice with a gun tip, transfer the lysate to a centrifuge tube, incubate on ice for 20 minutes, and allow the cells to fully lyse (please refer to Appendix 1 for the amount of reagent used, and the time for placing on ice should be adjusted according to different cell types). 4. Centrifuge at 14000 × g for 5-10 minutes.5. Transfer the supernatant to a new tube for further analysis. ● Suspension cell protein extraction1. Please remove the required Mammalian Protein Extraction Agent for pre cooling before protein extraction.2. Suspend 2500 × g of cells, centrifuge for 10 minutes, and discard the supernatant. Rinse cells with PBS. 2500 × g, centrifuge for 10 minutes, discard the supernatant.3. Add an appropriate amount of Mammalian Protein Extraction Agent, and 2-3 minutes before protein extraction, add Protein Inhibitor Cocktail in a ratio of 1:99, which is 1 x working solution.4. Add at least 1 ml of 1x working solution to every 100 mg of cells. If the extracted sample size is large, a small amount of 1x working solution can be used to resuspend the cells first, and then the remaining working solution can be added.5. After blowing evenly, place it on ice for 20 minutes to allow the cells to fully lyse (the time for placing it on ice should be adjusted according to different cell types). 6. Centrifuge at 14000 × g for 15 minutes.7. Transfer the supernatant to a new tube for further analysis.Table 1. Recommended usage of extraction reagents Cell culture plate type or dish type Extraction reagent usage 100 mm 500-1,000 µl 60 mm 250-500 µl 6-well culture plate 200-400 µl /well 24-well culture plate 100-200 µl /well 96-well culture plate 50-100 µl /well Table 2. Common Problems and Solutions Problem Possible reasons Resolvent Low extraction rate Low protein expression level Optimize transfection system Low extraction rate Insufficient reagent usage Increase the usage of extraction reagents Low extraction rate Reagent unable to dissolve cell membrane Increase cracking time or increase shaking amplitude Unable to obtain membrane protein This product is more suitable for extracting nuclear plasma protein Using eukaryotic cell membrane protein extraction kit... 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 |