Laccase And Its Immobilization

Laccase with copper is a polyphenol oxidase,not only exists in the secretions of the lacquer tree,but also in a variety of plants,insects and fungi.And the theoretical and applied researches on laccase start in biology,chemistry,physics,medicine and other areas.At present,laccase used in denim washing also gets more and more international attention.The tranditional washing methords include stone washing and chemical washing, and now cellulase is widely used in the denim washing for its environment friendly and efficiency.But the redyeing problem exists at the same time.Laccase solves the redying problem for its special degradation of indigo.In this article,the nature properties of the laccase were studied by using the direct copper blue 2R as substrate.The laccase showed highest activity at the followinging condition:pH 7,reaction temperature 70℃,the concentration of the copper ion 0.04 mmol/L.The optimal condition of laccase's denim washing:pH 7,laccase 4g/L, liquid ratio20:1,washing for a hour at 60℃,which could lead the discoloring rate to 28.5%,and there's no obviously back staining situation.The polyvinyl alcohol(PVA) bead crosslinked with glutaraldehyde agent was modified with epichlorohydrin to immobilize the laccase by covalent binding.The immobilization carrier beads got the most epoxy group at the folloeing condition: 2mol/L NaOH 20 mL,dimethylsulfoxide 40mL,epichlorohydrin 9mL,PVA beads 10 g,reacting for 5h at 60℃.But the direct copper blue 2R can't be degraded by the immobilized laccase.In order to verify the feasibility of the immobilization method,as a fixed object,α-amylase was well fixed in the epoxy PVA carrier,and the immobilizedα-amylase showed better acid-resistant and high temperature resistant than the freeα-amylase; When 8 times reused,its activity remains more than 60%.The key reason for the immobilization was that the laccase contained many additives.Puring the laccase may be helpful to the immobilization.