The oxidation state of copper in resting tyrosinase.

  title={The oxidation state of copper in resting tyrosinase.},
  author={Nobuo Makino and P E McMahill and H S Mason},
  journal={The Journal of biological chemistry},
  volume={249 19},
Resting tryosinase was diamagnetic between 1.4 K and 200 K. Redox titration showed that it, but not apotyrosinase, contained a titrable group, E’, = $0.36 volt (pH 7.0), R = 2. Upon denaturation with acid under strictly anaerobic conditions, the EPR-detectable copper increased from less than 5 % of the copper present to about 100%. It is concluded that the active site of the enzyme contains a pair of antiferromagnetically coupled Cu2+ ions.