Different concentration of HRP causes the same color on TMB. Why?

18 April 2022 0 7K Report

Hello everyone~

I prepared 1-20 nM of HRP (Mw= 40k) and then added 20 uM of TMB (sigma tablet) and H2O2. Finally, I got the exact same color (under uv-vis) after 1-30 mins. All solutions were in PBS (pH=7.4). Ideally, HRP was a catalyst and I can get gradient color with various concentrations of HRP. Why?

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