A simple assay for measuring cellobiose dehydrogenase activity in the presence of laccase

The commonly used assay for measuring cellobiose dehydrogenase (CDH) activi ty, based on the reduction of dichlorophenol-indophenol (DCIP), has been ad apted to measure this enzyme activity in the presence of laccase, which is often forced concurrently with CDH by a number of fungi. Laccase interferes with the assay by rapidly reoxidizing the reduced form of DCIP and can mas k CDH activity completely. It can be conveniently and completely inhibited by 4 mM fluoride in the assay, while CDH activity is only slightly affected by the addition of this inhibitor. The modified assay enables the detectio n of low CDH activities even in the: presence of very high excesses of lacc ase. It should be useful for screening culture supernatants of wood-degradi ng fungi for CDH since the assay is rapid and uses inexpensive and nontoxic reagents. Furthermore, it might be used for the detection of other enzyme activities which are assayed by following the reduction of quinones or anal ogue compounds such as DCIP. (C) 1999 Elsevier Science B.V. All rights rese rved.