Purpose | This immunoassay kit allows for the in vitro quantitative determination of bovine PCK concentrations in tissue homogenates and other biological fluids. |
Sample Type | Tissue Homogenate, Biological Fluids |
Analytical Method | Quantitative |
Detection Method | Colorimetric |
Specificity | This assay recognizes recombinant and natural bovine PCK. |
Cross-Reactivity (Details) | No significant cross-reactivity or interference was observed. |
Sensitivity |
< 0.078 ng/mL The sensitivity of this assay, or Lower Limit of Detection (LLD) was defined as the lowest detectable concentration that could be differentiated from zero. |
Characteristics | Bos taurus,Bovine,Phosphoenolpyruvate carboxykinase, cytosolic [GTP],PEPCK-C,Phosphoenolpyruvate carboxylase,PPCK1,4.1.1.32 |
Components | Reagent (Quantity): Assay plate (1×20ml), Standard (2), Sample Diluent (1×20ml), Assay Diluent A (1×10ml), Assay Diluent B (1×10ml), Detection Reagent A (1×120 μl), Detection Reagent B (1×120μl), Wash Buffer(25 x concentrate) (1×30ml), Substrate (1×10ml), Stop Solution (1×10ml), Plate sealer for 96 wells (5), Instruction (1) |
Material not included | Luminometer. Pipettes and pipette tips. EP tube Deionized or distilled water. |
Background | Phosphoenolpyruvate carboxykinase (or PEPCK) is an enzyme used in the natural process of gluconeogenesis. It converts oxaloacetate into phosphoenolpyruvate and carbon dioxide. It is found in two forms, cytosolic and mitochondrial. Whereas most reactions of gluconeogenesis can use the glycolysis enzymes in the opposite direction, the pyruvate kinase enzyme is irreversible. Therefore, the enzymes pyruvate carboxylase and phosphoenolpyruvate carboxykinase are used to provide an alternate path for effectively reversing its actions. PEPCK gene transcription (genetics) occurs in many species, and the amino acid sequence of PEPCK is distinct for each species. For example, its structure and its specificity differ in humans, Escherichia coli (E. coli), and the parasiteTrypanosoma cruzi. It has been shown that PEPCK catalyzes the reversible rate-controlling step of gluconeogenesis, the process whereby glucose is synthesized. The enzyme has therefore been thought to be essential in glucose homeostasis, as evidenced by laboratory mice that contracted diabetes mellitus type 2 as a result of the overexpression of PEPCK. A recent study suggests that the role that PEPCK plays in gluconeogenesis may be mediated by the citric acid cycle, the activity of which was found to be directly related to PEPCK abundance. PEPCK levels alone were not found to be highly correlated with gluconeogenesis in the mouse liver, as previous studies have suggested. Therefore, the role of PEPCK in gluconeogenesis may be more complex and involve more factors than was previously believed. PEPCK of Mycobacterium tuberculosis has been shown to trigger the immune system in mice by increasing cytokine activity. As a result, it has been found that PEPCK may be an 2 appropriate ingredient in the development of an effective subunit vaccination for tuberculosis. |
Sample Volume | 100 μL |
Plate | Pre-coated |
Protocol | The microtiter plate provided in this kit has been pre-coated with an antibody specific to PCK. Standards or samples are then added to the appropriate microtiter plate wells with a biotin-conjugated polyclonal antibody preparation specific for PCK and Avidin conjugated to Horseradish Peroxidase (HRP) is added to each microplate well and incubated. Then a TMB substrate solution is added to each well. Only those wells that contain PCK, biotin-conjugated antibody and enzyme-conjugated Avidin will exhibit a change in color. The enzyme-substrate reaction is terminated by the addition of a sulphuric acid solution and the color change is measured spectrophotometrically at a wavelength of 450 nm ± 2 nm. The concentration of PCK in the samples is then determined by comparing the O.D. of the samples to the standard curve. |
Reagent Preparation |
Bring all reagents to room temperature before use. Wash Buffer - If crystals have formed in the concentrate, warm to room temperature and mix gently until the crystals have completely dissolved. Dilute 30 mL of Wash Buffer Concentrate into deionized or distilled water to prepare 750 mL of Wash Buffer. Standard - Reconstitute the Standard with 1.0 mL of Sample Diluent. This reconstitution produces a stock solution of 20 ng/ml. Allow the standard to sit for a minimum of 15 minutes with gentle agitation prior to making serial dilutions (Making serial dilution in the wells directly is not permitted). The undiluted standard serves as the high standard (20 ng/ml). The Sample Diluent serves as the zero standard (0 ng/ml). ng/ml 20 10 5 2.5 1.25 0.625 0.312 0 Detection Reagent A and B - Dilute to the working concentration using Assay Diluent A and B (1:100), respectively. |
Sample Collection | Tissue homogenates - The preparation of tissue homogenates will vary depending upon tissue type. For this assay, tissue was rinsed with 1X PBS to remove excess blood, homogenized in 20 mL of 1X PBS and stored overnight at ≤ -20C. After two freeze-thaw cycles were performed to break the cell membranes, the homogenates were centrifuged for 5 minutes at 5000 x g. Remove the supernate and assay immediately or aliquot and store at ≤ -20C. Other biological fluids - Remove particulates by centrifugation and assay immediately or 3 aliquot and store samples at -20C or -80C. Avoid repeated freeze-thaw cycles. Note: Tissue homogenates and cell culture supernatant samples to be used within 7 days may be stored at 2-8 C, otherwise samples must stored at -20C (≤ 1 months) or -80C (≤ 2 months) to avoid loss of bioactivity and contamination. Avoid freeze-thaw cycles. When performing the assay slowly bring samples to room temperature. |
Assay Procedure |
4 Allow all reagents to reach room temperature (Please do not dissolve the reagents at 37C directly.). All the reagents should be mixed thoroughly by gently swirling before pipetting. Avoid foaming. Keep appropriate numbers of strips for 1 experiment and remove extra strips from microtiter plate. Removed strips should be resealed and stored at 4C until the kits expiry date. Prepare all reagents, working standards and samples as directed in the previous sections. Please predict the concentration before assaying. If values for these are not within the range of the standard curve, users must determine the optimal sample dilutions for their particular experiments. |
Calculation of Results |
Average the duplicate readings for each standard, control, and sample and subtract the average zero standard optical density. Create a standard curve by reducing the data using computer software capable of generating a four parameter logistic (4-PL) curve-fit. As an alternative, construct a standard curve by plotting the mean absorbance for each standard on the x-axis against the concentration on the y-axis and draw a best fit curve through the points on the graph. The data may be linearized by plotting the log of the PCK concentrations versus the log of the O.D. and the best fit line can be determined by regression analysis. It is recommended to use some related software to do this calculation, such as curve expert 13.0. This procedure will produce an adequate but less precise fit of the data. If samples have been diluted, the concentration read from the standard curve must be multiplied by the dilution factor. |
Restrictions | For Research Use only |
Handling Advice |
1. The kit should not be used beyond the expiration date on the kit label. 2. Do not mix or substitute reagents with those from other lots or sources. 3. If samples generate values higher than the highest standard, further dilute the samples with the Assay Diluent and repeat the assay. Any variation in standard diluent, operator, pipetting technique, washing technique,incubation time or temperature, and kit age can cause variation in binding. 4. This assay is designed to eliminate interference by soluble receptors, ligands, binding proteins, and other factors present in biological samples. Until all factors have been tested in the Immunoassay, the possibility of interference cannot be excluded. |
Storage | 4 °C/-20 °C |
Storage Comment | The Standard, Detection Reagent A, Detection Reagent B and the 96-well strip plate should be stored at -20 °C upon being received. The other reagents can be stored at 4 °C. |