Vector Laboratories offers a number of reagents for the detection of blotted protein samples. These reagents can recognize epitopes, fusion protein tags, or carbohydrate groups in the targeted protein. The choice of reagents will depend on the nature of the target protein and the chosen visualization method. Sensitivity, reproducibility, and ease of use are important considerations when choosing detection reagents.

One-Step Fluorescence Detection. Fluorochrome conjugated secondary antibodies may be used to detect an unconjugated primary antibody on a blot. These fluorescent detection reagents are used in conjunction with the proper membrane and visualization equipment. This method is fast and simple and allows multiple targets to be visualized simultaneously. Fluorescent reagents are listed and described in detail in “Immunofluorescence”. This section focuses on the more common enzyme-based detection methods.

One-Step Enzymatic Detection. One-step enzymatic detection offers greater sensitivity and more versatility due to the types of detection reagents and enzyme substrates available. For one-step detection, alkaline phosphatase (AP) and peroxidase (HRP) conjugated secondary antibodies are available.

Amplified Detection with Biotin/Avidin and Biotin/Streptavidin Systems. Biotin/avidin or biotin/streptavidin detection systems offer the greatest sensitivity by signal amplification and the greatest flexibility in detection methods. The VECTASTAIN® ABC-AmP™ kits, for example, are complete detection systems that offer sensitivity, reliability, and versatility. Streptavidin or avidin based reagents can detect a variety of macromolecules on the blot: biotinylated secondary antibodies, biotinylated antibodies against fusion protein tags, biotinylated lectins, and even biotinylated target proteins blotted directly onto the membrane.

Enzyme Substrates. Substrates that produce either a visible chromogenic precipitate or a chemiluminescent/ chemifluorescent signal can be used for visualization. Alkaline phosphatase allows sustained substrate conversion and increased sensitivity with low background. Peroxidase has faster reaction kinetics resulting in a more rapid signal development. Vector Laboratories offers a variety of proprietary peroxidase and alkaline phosphatase substrates that not only satisfies sensitivity requirements and personal preferences, but also allows multiple targets to be visualized simultaneously on the blot. In addition, our DuoLuX™ Chemiluminescent/Chemifluorescent substrates provide highly sensitive chemiluminescent and chemifluorescent visualization.