| Abstract: | We conducted a systematic study of covalent immobilisation of Agaricus bisporus tyrosinase onto typical enzyme carriers. Acrylic beads, two commercial silica gels with different pore structures and mesoporous
silica foam (MCFs) beads functionalised using different organosilanes showed that only aminated MCFs offer active preparations
with immobilisation efficiencies greater than 100% and a similar ratio of diphenolase (L-DOPA) to monophenolase (L-tyrosine)
activities as the free enzyme. The native enzyme was entirely inactivated during incubation at 55°C for 30 min, whereas the
enzyme immobilised on acrylic carrier or MCF retained 46 and 35%, respectively, of the initial activity after similar treatment.
Susceptibility of native and immobilised tyrosinase to suicide inactivation in the presence of L-tyrosine and L-DOPA was tested
in repeated batch tests. However, none of the preparations obtained in the L-DOPA solution was operationally stable enough
to be used for practical applications. |
