[Cell-biology] Cytoplasmic marker enzyme (Plant)

[Jana Hakenjos]

Dear all,

I am isolating chloroplasts from Physcomitrella patens (a moss) via a
Percoll density gradient. To test for contaminations from other
compartments I want to measure enzyme activities. But I can't find a
good candidate for the cytoplasm that fulfils following "requirements":

- no isoenzyme(s) in plastids!!!!!
- easy to measure- most preferable spectrometric
- no radioactive assay

My first try was alcohol dehydrogenase but I couldn't detect any
activity- most likely it isn't expressed under my conditions.

I am thankful for every hint!

Thank you very much in advance,

Jana Hakenjos