Hi knowledgeable beings,

I am still grappling with the fact that people assay pNPA hydrolysis at 348nm. As far as, I understand esterase activities are always measure at 400 or 405 nm, but this is not the case for carbonic anhydrases.

In the lab: I took the chance to check both spectra expecting to get a similar kinetic slope, however, they are not similar. I looked in theory for some information but I can't find a palpable reason behind it, apart from the balance between charges of pNP and pNP-

I hope there is an answer out there.

Thanks!