Investigators are studying a protein that must be phosphorylated to be activated. Which method could be used to separate the phosphorylated form of the protein from the form that lacks an activating phosphate group?

A. differential centrifugation

B. equilibrium sedimentation

C. velocity sedimentation

D. ion-exchange chromatography

E. gel-filtration chromatography

Ion-exchange chromatography.

Explanation:

Phosphorylation is a posttranslational modification that confers to the proteins different charges, thereby ion-exchange chromatography can be used for the identification of phosphorylated and unphosphorylated protein species. Both ion-exchange chromatography and mass spectrometry are used to analyze protein phosphorylation  

allowed for the prediction of the properties of missing elements.

gold i'm pretty sure i might be wrong