If you have an inhibitor that is selective for one of the two enzymes, then you can inhibit one of them in the mixture to figure out how much of the activity is due to each enzyme.

Thanks for your answer Adam B Shapiro. Really I do not know which inhibitor can inhibit one of them or both, I think it is difficult.

I think about the separation and purification of both of them, but this will be in a late stage. Now I want to study the production of both in a crude mixture.

Thanks

If one of the enzymes requires a cofactor or cosubstrate that the other one does not require, then you can differentiate their activities by conducting the reaction with and without the cofactor or cosubstrate, as long as it is not already present in the extract.

MnP requires Mn(II) and peroxide as substrates. Mn(II) is probably already in the extract. Although it could be bound up by a chelator such as EDTA, this might also inhibit laccase, which depends on copper.  Omitting peroxide, and introducing the enzyme peroxidase to consume any peroxide in the sample that may form, should eliminate the activity of MnP, allowing you to measure laccase activity selectively.

Laccase is inhibited by a variety of small ions (azide, cyanide, fluoride). If any of these don't inhibit MnP, then you can use them to measure MnP activity selectively.

Many thanks Adam B Shapiro. Really I have not any problem with detection of laccase activity, as you mentioned it did not require Mn or peroxide, but when I assess MnP as you know there is some interference between the both.

Thanks for your help

Manganese peroxidase might have three different activities, two that are Mn-dependant and are  based on the conversion of Mn(II) into Mn(III). The Mn(III) form complexes with α-hydroxy acids (1) and oxidizes lignin-like substrate (2). The third one is residual and works in the absence of Manganese. Meanwhile, it is the second one that might interfere with laccase activity. But, just measuring the complexation of Mn with  α-hydroxy acids such as tartrate, oxalate or malonate, might be a way to overcome the interference. You can check this article "Purification and catalytic properties of two manganese peroxidase isoenzymes from Pleurotus eryngii" by Martinez et al. (1996) or the one attached. Meanwhile, as Dr. Sahpiro pointed it out, manganese might be present in your media,  so I would recommend that you quantify it or eliminate it before doing assay for both MnP and laccase activities, so that laccase activity assay doesn't include MnP. In the same scope, I would suggest that you measure or just check for the presence of hydrogen peroxide, some facultative enzymes such as glucose oxidase or galactose oxidase might be produced depending on your media and growth conditions. I would also recommend this excellent review for understanding more about ligninolytic enzymes: "Structure and action mechanism of ligninolytic enzymes" by Wong (2009).

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