Improvement of the signal-to-noise ratio on the fluorescent detection of a membrane protein using horse radish peroxidase

Horseradish peroxidase (HRP) is used as a sensitizing enzyme to detect a membrane protein with high sensitivity. In this method, the membrane protein is labeled with HRP, and fluorescent group-modified tyramide is used as a substrate for fluorescent signal amplification. However, a high background signal due to a nonspecific adsorption of fluorescent group- modified tyramide to cells is known to compromise high-sensitive detection. Here, we designed a new substrate in which tyramide was changed to tyrosyltaurine. Because the background signal was greatly reduced by the sulfonate group in the new substrate, the signal- to-noise ratio was greatly improved compared with a commercial substrate.