Enhanced chemiluminescence (ECL) substrates, are HRP substrates that are typically two-component systems consisting of a stable peroxide solution and an enhanced luminol solution. To make a working solution, the two components are mixed together. When incubated with a blot on which HRP-conjugated antibodies (or other probes) are bound, a chemical reaction emits light at 425 nm which can be captured with x-ray film, CCD camera imaging devices and phosphorimagers that detect chemiluminescence. Light emission occurs only during the enzyme-substrate reaction; therefore, once the substrate in proximity to the enzyme is exhausted, signal output ceases.
We offer six types of ECL substrates for western blot detection with horseradish peroxidase enzyme (HRP). Each containing different enhancers to increase signal, linearity and duration compared to other western blot detection systems. Use the table above to select the most appropriate ECL kit based on abundance of your target protein of interest, abundance of sample containing the target protein, and the level of sensitivity and type of instrumentation available for detection.
Don’t know which ECL western blot kit is right for you? Use the chemiluminescent HRP substrate selection guide to choose the right HRP substrate for your research needs.
Why do our ECL kits have recommended antibody dilutions?
Under optimal western blotting conditions, a chemiluminescent signal can last for 6–24 hr. The level and duration of light generation depends on the specific substrate being used and the enzyme-to-substrate ratio in the system. Although the amount of substrate on a blot is relatively constant, the amount of enzyme present depends on the amount of antibody-conjugate added. Too much enzyme conjugate applied to a western blot system is one of the greatest causes of signal variability, dark background, short signal duration, and low sensitivity. A signal emission curve that decays slowly is desirable as it demonstrates that each component of the system has been optimized and allows reproducible results. A signal that decays too quickly can cause variability, low sensitivity, high background, and problems with signal documentation. A long-lasting signal minimizes variability in results due to transfer efficiency, different manufacturer lots of substrate, and other factors. The oxidation reaction of the HRP molecules with the luminol in the substrate produces free radicals in addition to the light being produced. An abundance of HRP in the system will create an abundance of free radicals, speeding the probability of HRP inactivation. Free radicals may also damage the antigen, antibodies, and the membrane, resulting in reduced effectiveness of re-probing.