Hello,

Casein as a globular protein is quite soluble at neutral pH to start with (it is the main proteic constituent of milk).

Why do you want to put it in NaOH? You can most probably just dissolve it in the buffer you use for your inhibition assay if its pH is neutral.

Greetings,

David

Sodium caseinate is much easier to work with in my experience. NaoH does help with casein solubility but be careful not to cause structural changes which increase protease susceptibility.

hammarsten casein disolves in Tris-HCl pH 7.5 with the help of heat. Get the protein in the buffer and heat the flask in a microwave oven for a while and then stirr. The pH is usend to analyze serine peptidase activity with or without inhibitors.