Leptin (LEP) ELISA Kit

Antigen: Leptin (LEP)

Synonyme: OB, OBS, FLJ94114, ob, obese

Reaktivität: Schaf

Applikation: ELISA

Zertifikate: ISO 9001:2008

Produktnummer: ABIN367587

Produktbeschreibung

Produktmerkmale: This immunoassay kit allows for the in vitro quantitative determination of Small Tailed Han Sheep LEP concentrations in cell culture supernates, serum, plasma and other biological fluids.

Proben: Serum, Plasma

Beschreibung: Leptin is a 16 kDa protein hormone that plays a key role in regulating energy intake and energy expenditure, including appetite and metabolism. Leptin is one of the most important adipose derived hormones. The Ob(Lep) gene (Ob for obese, Lep for leptin) is located on chromosome 7 in humans. Leptin interacts with six types of receptors (Ob-Ra–Ob-Rf, or LepRa-LepRf) which in turn are encoded by a single gene, LEPR. Ob-Rb is the only receptor isoform that can signal intracellularly via the Jak-Stat and MAPK signal transduction pathways, and is present in hypothalamic nuclei. In addition to being a biomarker for body fat, serum leptin levels also reflect individual energy balance. Several studies have shown that fasting or following a very low calorie diet (VLCD) lowers leptin levels. It might be that on short term leptin is an indicator of energy balance. This system is more sensitive to starvation than to overfeeding, i.e. leptin levels do not rise extensively after overfeeding. It might be that the dynamics of leptin due to an acute change in energy balance are related to appetite and eventually to food intake. Although this is a new hypothesis, there are already some data that support it. Leptin binds to the ventromedial nucleus of the hypothalamus, known as the "appetite center." Leptin signals to the brain that the body has had enough to eat, or satiety. A very small group of humans possess homozygous (same on both of the pair) mutations for the leptin gene which leads to a constant desire for food, resulting in severe obesity. This condition can be treated successfully by the administration of recombinant human leptin. Thus, circulating leptin levels give the brain input regarding energy storage so it can regulate appetite and metabolism. Leptin works by inhibiting the activity of neurons that contain neuropeptide Y (NPY) and agouti-related peptide (AgRP), and by increasing the activity of neurons expressing α-melanocyte-stimulating hormone (α-MSH). Leptin is also strongly linked with angiogenesis, increasing Vascular endothelial growth factor (VEGF) levels. Although leptin is a circulating signal that reduces appetite, in general, obese people have an unusually high circulating concentration of leptin. These people are said to be resistant to the effects of leptin, in much the same way that people with type 2 diabetes are resistant to the effects of insulin. The high sustained concentrations of leptin from the enlarged adipose stores result in leptin desensitization. The pathway of leptin control in obese people might be flawed at some point so the body doesn't adequately receive the satiety feeling subsequently to eating.

Spezifität: This assay recognizes recombinant and natural Small Tailed Han Sheep LEP. No significant cross-reactivity or interference was observed.

Anwendungen

Prinzip: The microtiter plate provided in this kit has been pre-coated with an antibody specific to LEP. Standards or samples are then added to the appropriate microtiter plate wells with a biotin-conjugated polyclonal antibody preparation specific for LEP and Avidin conjugated to Horseradish Peroxidase (HRP) is added to each microplate well and incubated. Then a TMB (3,3',5,5' tetramethyl-benzidine) substrate solution is added to each well. Only those wells that contain LEP, 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 LEP in the samples is then determined by comparing the O.D. of the samples to the standard curve.

Protokoll: Preparation of Reagents: Bring all reagents to room temperature before use. 1. Wash Buffer If crystals have formed in the concentrate, warm up to room temperature and mix gently until the crystals have completely dissolved. Dilute 20 ml of Wash Buffer Concentrate into deionized or distilled water to prepare 500 ml of Wash Buffer. 2. 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. The undiluted standard serves as the high standard (20 ng/ml). The Sample Diluent serves as the zero standard (0 ng/ml). 3. Biotin-antibody Dilute to the working concentration specified on the vial label using Biotin-antibody Diluent(1:100), respectively. 4. HRP-avidin Dilute to the working concentration specified on the vial label using HRP-avidin Diluent(1:100), respectively. Precaution: The Stop Solution provided with this kit is an acid solution. Wear eye, hand, face, and clothing protection when using this material. Sample Collection and Storage: Cell Culture Supernates Remove particulates by centrifugation and assay immediately or aliquot and store samples at -20° C. Avoid repeated freeze-thaw cycles. Serum Use a serum separator tube (SST) and allow samples to clot for 30 minutes before centrifugation for 15 minutes at 1000 g. Remove serum and assay immediately or aliquot and store samples at -20° C. Avoid repeated freeze-thaw cycles. Plasma Collect plasma using citrate, EDTA, or heparin as an anticoagulant. Centrifuge for 15 minutes at 1000 g within 30 minutes of collection. Assay immediately or aliquot and store samples at -20° C. Avoid repeated freeze-thaw cycles. Assay Procedure: 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 y-axis agaLEPt the concentration on the x-axis and draw a best fit curve through the points on the graph. The data may be linearized by plotting the log of the LEP concentrations versus the log of the O.D. and the best fit line can be determined by regression analysis. 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. Limitations of the Procedure: The kit should not be used beyond the expiration date on the kit label. Do not mix or substitute reagents with those from other lots or sources. It is important that the Calibrator Diluent selected for the standard curve be consistent with the samples being assayed. If samples generate values higher than the highest standard, dilute the samples with the appropriate Calibrator 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. This assay is designed to eliminate interference by soluble receptors, binding proteLEP, and other factors present in biological samples. Until all factors have been tested in the Immunoassay, the possibility of interference cannot be excluded.

Testdurchführung: Assay Time: 1-3h
Sample Volume: 50-100ul

Applikationshinweise: Detection Wavelength: 450 nm

Bestandteile: Reagent Quantity Assay plate 1 Standard 2 Sample Diluent 1 x 20 ml Biotin-antibody Diluent 1 x 10 ml HRP-avidin Diluent 1 x 10 ml Biotin-antibody 1 x 120µl HRP-avidin 1 x 120µl Wash Buffer 1 x 20 ml (25×concentrate) TMB Substrate 1 x 10 ml Stop Solution 1 x 10 ml STORAGE 1. Unopened test kits should be stored at 2-8°C upon receipt and the microtiter plate should be kept in a sealed bag with desiccants to minimize exposure to damp air. The test kit may be used throughout the expiration date of the kit. Refer to the package label for the expiration date. 2. Opened test kits will remain stable until the expiring date shown, provided it is stored as prescribed above. 3. A microtiter plate reader with a bandwidth of 10 nm or less and an optical density range of 0-3 OD or greater at 450nm wavelength is acceptable for use in absorbance measurement.

Benötigtes Material: Microplate reader capable of measuring absorbance at 450 nm, with the correction wavelength set at 540 nm or 570 nm. Pipettes and pipette tips. Deionized or distilled water. Squirt bottle, manifold dispenser, or automated microplate washer.

Lagerung: 1. Unopened test kits should be stored at 2-8°C upon receipt and the microtiter plate should be kept in a sealed bag with desiccants to minimize exposure to damp air. The test kit may be used throughout the expiration date of the kit. Refer to the package label for the expiration date. 2. Opened test kits will remain stable until the expiring date shown, provided it is stored as prescribed above. 3. A microtiter plate reader with a bandwidth of 10 nm or less and an optical density range of 0-3 OD or greater at 450nm wavelength is acceptable for use in absorbance measurement. Expiration date: six months from the date of manufacture.

Forschungsgebiet: Hormone

Beschränkungen: Nur für Forschungszwecke einsetzbar