Chemical modification and immobilisation of laccase from Trametes hirsuta and from Myceliophthora thermophila.
Laccase from two different source organisms, Myceliophthora thermophila and Trametes hirsuta, were subjected to chemical modification in solution by (i) two bifunctional reagents, ethylene-glycol-N-hydroxy succinimide (EGNHS) and glutaraldehyde and (ii) by the monofunctional citraconic anhydride. The untreated and chemically modified forms of both enzymes were then immobilised onto three different types of mesoporous silicate (MPS) particle (MCM, CNS and SBA-15). Thermal stabilities of native, modified-soluble and immobilised laccases were then evaluated. Although the two laccases have similar lysine contents, those of M. thermophila are clearly more amenable to chemical modification. Treatment of the M. thermophila enzyme with EGNHS led to a 8.7-fold increase in thermal stability over the free soluble enzyme while glutaraldehyde gave a 5.7-fold increase. Increased activity of M. thermophila laccase occurred only with citraconic anhydride modification (a 3-fold increase), while the glutaraldehyde modification marginally increased the activity of the T. hirsuta enzyme (by 1.2-fold). Upon immobilisation onto MPS, the greatest increase in stability was for the glutaraldehyde-treated M. thermophila preparation on SBA-15 (24-fold over the soluble enzyme). Chemical modification of laccase from T. hirsuta with both glutaraldehyde and EGNHS gave only a 2-fold increase in stability, increasing >4-fold upon immobilisation onto SBA-15 and MCM-41/98.
School of Biotechnology & National Centre for Sensors Research, Dublin City University, Dublin 9, Ireland.
Jessica
J
Forde
School of Biotechnology & National Centre for Sensors Research, Dublin City University, Dublin 9, Ireland.
Elizabeth
E
Tully
Research Institute of Membrane and Systems Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.
Alex
A
Vakurov
Research Institute of Membrane and Systems Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.
Tim D
TD
Gibson
Research Institute of Membrane and Systems Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.
Paul
P
Millner
School of Biotechnology & National Centre for Sensors Research, Dublin City University, Dublin 9, Ireland. Electronic address: ciaran.fagan@dcu.ie.
Ciarán
C
Ó'Fágáin
Chemical modification; Immobilisation; Laccase; Mesoporous silicates; Stabilisation