STABILIZATION OF THE OXY FORM OF TYROSINASE BY A SINGLE CONSERVATIVE AMINO-ACID SUBSTITUTION

Asp-208 of Streptomyces glaucescens tyrosinase (an invariant residue in the Cu(B)-binding region of tyrosinases and haemocyanins) was conservatively substituted by glutamic acid. Although having little effect on spectroscopic or kinetic properties of the enzyme, the mutation greatly decreased the lability of Cu-bound O2. A rationalization for these results is given, based on the crystal structure of Panulirus interruptus haemocyanin in the conserved Cu(B)-binding region.