Tyrosinase reaction rates reaches maximal velocity in less than two minutes where an initial burst phase is followed by steady-state kinetics. In addition, the substrate MBTH (3-methyl-2-benzothiazolinone hydrazine) is unstable and a fresh stock needs to be prepared and kept in dark until use. Given these reasons, it is very easy to miss the narrow window to measure the initial rate of reaction with also Tyrosinase (human), (recombinant) (His-tag) (BML-SE535).