Medium engineering to enhance mushroom tyrosinase stability

Tyrosinase could have many applications including biotransformation, bioremediation, and in biosensors. However, its application, especially at industrial scale, is seriously limited by its rapid inactivation. To increase mushroom tyrosinase (MT) stability, the enzyme was entrapped in different matrixes. Then, the structural and operational stability of the entrapped mushroom tyrosinase (EMT) were examined in one-phase-binary solutions (OPBS) obtained by mixing different amounts (0–100%) of water-miscible solvents such as acetonitrile and 2-propanol with PBS. Experiments showed MT lost all of its activity upon entrapment in the classical sol–gels and hybrid silica sol–gels, but could retain up to 25% of its activity in cross-linked polyacrylamide (CLP). These studies revealed while EMT in CLP was losing about 0.06% of its structural stability per hour in PBS, OPBS containing 2-propanol (50 or 75%) did not affect the EMT structural stability and increased its cresolase activity up to 1.5 fold during 50 days storage at 4 °C. The aquaphilicity of CLP helps EMT to function normally in OPBS and using 2-propanol (50% or more) in such media not only stopped EMT loss from the sieve structure of the CLP, but it was also beneficial to the more hydrophobic substrates. Using tyrosine as a substrate in OPBS containing 2-propanol (75%), l-DOPA production reached 4.21 ± 0.23 μM/min−1.

► Development of an entrapping method for mushroom tyrosinase. ► Studying the combination of one-phase-binary solution and cross-linked polyacrylamide for entrapping enzymes. ► Changes in the functional and structural properties of mushroom tyrosinase under the conditions selected.