This kit is not capable of determining enzymatic activity. The product is intended for use in measuring total antioxidant capacity (TAC) of a given sample as compared to a standard curve based on serial dilutions of Trolox. The kit principal is based on the reduction of Cu2+ to Cu+. Please see the link below to review additional information in the product datasheet:
https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/product/documents/114/194/mak334bul.pdf
Note that there are other kit products available for measuring the activity of specific enzymes.