Dear Andi,

Casein dissolves at once in dilute solutions of monobasic alkalies such as sodium hydroxide and also in excess of lime-water to a clear solution. When treated with dilute NaOH solutions, casein forms soluble sodium caseinate.

Therefore, I suggest to dissolve it in dilute solution of NaOH. In pure distilled water casein will aggregate and will not dissolve.

http://www.jbc.org/content/35/1/127.full.pdf

Hoping this will be helpful,

Rafik

Dear Andi Adimas

You can dissolve casein in 50mM potassium phosphate buffer, pH 7.5. Also it is possible to use EDTA instead of PBS for solubilization of caseins.

Please you can find publication in the following link: http://www.pnas.org/content/53/2/392. or http://www.sigmaaldrich.com/life-science/learning-center/life-science-video/universal-protease.html

Cordialy

Marius

 Dear Mr. Rafik and Mr. Marius, thank you for you answers.