Why do mushrooms turn brown?

The research team of Annette Rompel from the Institute for Biophysical Chemistry, University of Vienna explore the mechanisms behind the "browning reaction" during the spoilage of mushrooms. The researchers were able to demonstrate that the enzyme responsible is already formed prior to fungal spoiling. The detailed study is published online in the well renowned journals, Phytochemistry and Acta Crystallographica. Understanding the mechanism of enzyme tyrosinase pigmentation is currently of both medical as well as technological interest. The copper-containing enzyme is present in animals and humans and is essential for the protective pathway against UV radiation, it also simultaneously provides the elucidation and potential means with which to prevent the spoilage of food. Mushrooms were selected for the study due to their low cost and ready availability. In addition they are also a valuable target for researchers, largely because of their high enzyme content, fungi are ideal sources for potential studies of tyrosinase. The mushrooms therefore serve as a model organism for the study of the pathway involved in food spoilage. Elucidation of an inactive precursor Since 2012, it has become established that six different tyrosinases (PPO1 to 6) exist within the mushroom, two of which (PPO3 and PPO4) occur in larger quantities. The enzyme responsible for the mechanism of food spoilage is formed within eukaryotes (organisms that have a nucleus) as an inactive precursor during the developmental phase of an organism. This precursor is then activated via specific chemical cleavage. At this cleavage site, the protein segment covering part of the enzyme active site is removed and the substrates (tyrosine and other monophenols) can be accessed and take part in key chemical reactions. New Method of Isolation and unique reagent leads to success