Are any of the colorimetric substrates generally used for spec assays of laccase specific to laccase ONLY? Or do other enzymes potentially increase the reading? What about syrangaldazine or guaiacol?
Hello, to find an absolutely specific substrate for laccases is quite not a simple task. In fact, most laccase substrates are also good peroxidase substrates, and moreover others are also catecholase (phenolase) substrates. Guaiacol is not very comfortable as it is an oily, strongly smelling, readily (auto)oxidizable substrate. On the contrary, syringaldazine is a stable crystalline powder, soluble in ethanol, and giving a strongly colored, univocal product, whose molar extinction is well known. Unluckily, syringaldazine is also a good substrate for peroxidases too, so a pretreatment with catalase to destroy endogenous hydrogen peroxide is necessary, unless you are working on a (partially) purified preparation, from which hydrogen peroxide and substrates of hydrogen-peroxide-generating oxidases have been already removed, for example by dialysis.
In addition to the former message, I would suggest DMP (2,6-dimethoxyphenol). It shows some advantages in relation to guaiacol (similar structure, but more easily oxidized by laccase with low potential) and syringaldazyne (the color product of oxidized DMP is more stable than syringaldazine). But the most imporatn think is that laccases do not need any other substrate (air oxygen is enough). Peroxidases need H2O2, Possible useful to read Solano ET AL., dimethoxyphenol oxidase activity of different microbial blue multi-copper proteins. 204, 175-181, 2001, FEMS Microbiol. Lett.
Good luck
For laccase production should we add substrate in liquid media for broth assay?
- Badges
- Science topic
- Similar topics
- Chemistry
- Biochemistry