Abstract: An improved spectrphotometric procedure for laccase assay is presented in the paper.The spectrophotometer,which was the product of the Japanese SHIMADZU company, was used to record continuously the time course curve of the laccase catalyzed reaction at the wavelength of 420 nm at 25 ℃ with ABTS[2,2′ azino bis (3 ethylbenzothiazoline 6 sulphonate)] as the substrate to measure the initial velocity. And the optimum pH for the laccase sample A or B was 4.0 or 4.5 in Britton Robinson buffer(0.04 mol/L) at 25 ℃,respectively. The two most significant parameters in the Michaelis Menten theory, the Michaelis constant K m and the maximum Michaelis Menten velocity V max , were determined from a Lineweaver Burk plot. The K m for the laccase A or B was 6.64×10 -5 mol/L or 2.21×10 -5 mol/L,respectively.And V max for the laccase A or B was 1 425 μmol∕(L·min) or 325 μmol∕(L·min),respectively. The laccase A or B was recommended to dilute for a hundred thousand times with Britton Robinson buffer of optimum pH at 25 ℃ because the time course curves for the laccase A or B was linear within 4 minutes.

Key words: ffthopone, kill and calcinator, proce ss control, achromic ability, ellergv