Title

Tyrosinase Concentration and Specific Activity in Five World Mushroom Species of Central Minnesota: A Biochemical Analysis

Document Type

Thesis

Publication Date

2002

Advisor

David Mitchell, Biology

Abstract

Tyrosinase is a copper-containing enzyme with a total molecular weight of 128,000 that catalyzes two types of reactions: the hydroxylation of an orthro-phenol and the oxidation of L-3, 4 dihydroxyphenlyalanine (L-DOPA) to an orthro-quinone. In mammals, tyrosinase acts within pigment producing cells, called melanocytes, in the pathway that formulates melanin. If for some reason, this mechanism becomes dysfunctional, cancer or vitiligo may develop. In plants and fungi tyrosinase is believed to act at a bruise site to convert phenols to quinines, which may aid in a metabolic signaling response. Tyrosinase also acts in the browning of fruits and fungi, and thus its study and further understanding may provide economic benefit to the agricultural industry. This investigation specifically examined the tyrosinase concentration and specific activity in five wild mushrooms that were collected in the summer and fall of 2001 in and around Saint John’s University. The five mushrooms collected were morphologically identified as: Agaricus bisponls, Agaricus placomyces, Leucoagaricus brunneus, Collybia sp., and Amanita bisporigera. It has been previously demonstrated that both the concentration and specific activity of tyrosinase differ between domestic mushroom species, but these biochemical properties of tyrosinase have not been examined in wild mushrooms. It has been previously demonstrated that both the concentration and specific activity of tyrosinase differ between domestic mushroom species, but these biochemical properties of tyrosinase have not been examined in wild mushrooms. It was proposed that this difference of tyrosinase specific activity and concentration will be found in wild mushrooms as well. In order to test this hypothesis, activity assays and Bradford assays were completed. The data gathered in this investigation showed that there is great variance in the protein concentration (with the solute extract values ranging from 46. 16ug to 82.91 ~g) and in specific activities (values ranging from 0.047 Units/~g protein to 1.21 Units/~g protein). Thus, the hypothesis that the differences in tyrosinase concentration and specific activity that has previously been observed in domesticated mushrooms will be found in wild mushrooms as well was supported in this investigation.

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