Studies of the enzyme laccase

Rhus Vernicifera laccase was purified to an A_(280)/A_(614) ratio of 15.2. A procedure was then used to selectively remove the Type 2 copper and 70% of it was removed as judged by EPR. The treated enzyme showed decreased absorbance in the 330 nm, region, which is associated with the Type 3 site, The blue color was observed to reversibly bleach on occasion, apparently due to autoreduction of the Type 1 copper. The fluorescence of the Type 2 depleted laccase was increased 60% over that of the native protein. Since fluorescence quenching is often associated with binding of a metal to a protein site, fluorescence was used to monitor the attempted substitution of cobalt and nickel into the Type 2 site, There is some evidence that cobalt can occupy the Type 2 site