ACTIVATION PARAMETERS FOR THE RECONSTITUTION OF APOTYROSINASE BY COPPER

The reaction of apotyrosinase with divalent copper to give enzymatical ly active tyrosinase has been studied at pH 8.2 and temperatures from 278 to 303 K. At a 10-fold excess of Cu(II) over enzyme, the pseudo-fi rst order rate constants range from 1.32 x 10(-3) s-1 to 2.93 x 10(-2) s-1 and yield activation parameters of DELTAH(not-equal) = 85 +/- 3 k J . mol-1 and DELTAS(not-equal) 5 +/- 20 J . mol-1 K-1. The near zero value for the entropy of activation is discussed.