Skip to ContentSkip to Navigation
About usNews and EventsNews articles

Crystal structure of agaricus bisporus tyrosinase

24 June 2011

PhD ceremony: Mr. W.T. Ismaya, 14.45 uur, Doopsgezinde Kerk, Oude Boteringestraat 33, Groningen

Dissertation: Crystal structure of Agaricus bisporus tyrosinase

Promotor(s): prof. B.W. Dijkstra, prof. H.J. Wichers

Faculty: Mathematics and Natural Sciences


A tyrosinase from the mushroom Agaricus bisporus has successfully been crystallized by Wangsa Ismaya and its structure was elucidated by means of X-ray crystallography.

The structure of this copper-containing enzyme shows a tetramer of two heavy (H) and two light (L) subunits, which is the species occurring physiologically. The H subunit appeared to be the gene product of ppo3 and has the typical fold of type 3 binuclear copper proteins, although with several extensions of the peptide chain. The L subunit originates from orf239342. Its structure resembles that of proteins with agglutinating activity, but the carbohydrate binding residues are not conserved; therefore its function is not yet clear. The tyrosinase structure shows how calcium ions stabilize the tetramer. A thioether bond, which occurs between the Cu-A coordinating His85 and the adjacent Cys83, is present in the active site. This thioether bond restricts the rotational freedom of the His85 side chain. A structure of PPO3 with bound tropolone shows that this inhibitor forms a pre-Michaelis complex with the enzyme. It occupies a similar position to that of phenylthiourea in the structure of catechol oxidase, a tyrosinase homolog. Further details of the reaction mechanism remain unclear in the absence of data on the oxygen-bound (oxy-state) of the enzyme. Nevertheless, the presence of a thioether bond suggests that the current catalytic mechanism, which requires His85 to be flexible, should be updated. In addition, the structure provides now a solid base for the biochemical characterization of the L subunit.

Last modified:15 September 2017 3.41 p.m.

More news

  • 17 April 2019

    Why lightning often strikes twice

    In contrast to popular belief, lightning often does strike twice, but the reason why a lightning channel is ‘reused’ has remained a mystery. Now, an international research team led by the University of Groningen has used the LOFAR radio telescope to...

  • 16 April 2019

    Still going strong after four decades

    On March 29th professor of Applied Physics Jeff de Hosson was offered a farewell symposium, a few months after his official retirement date near the close of 2018. ‘But 29 March was the 100th birthday of Jan Francken, my predecessor.’ Besides, De Hosson...

  • 11 April 2019

    Ben Feringa in orbit around the Sun

    Dozens of minor planets that used to orbit the Sun anonymously were named by the International Astronomical Union on 6 April 2019. The asteroid that used to be known as ‘minor planet 12655’ was named after Prof. Ben Feringa, winner of the 2016 Nobel...