First of all congratulations for succeeding to immobilize your enzyme. I have searched the literature to find examples of immobilized tyrosinase and my search revealed the studies contained in the following links and a publication which is attached to this answer:
First you need to determine the Immobilization efficiency and immobilization yield.
Once you have idea of amount of protein loaded onto the particle or matrix you can find out the specific activity for the loaded protein.
Calculate the total protein of your stock enzyme and subtract the protein in supernatent or unbound protein. This will give you idea of amount of protein loaded and determine the specifc activty.