Nitrilotriacetic Acid-Derivatized Quantum Dots for Simple Purification and Site-Selective Fluorescent Labeling of Active Proteins in a Single Step

We demonstrate that QDs coated with nitrilotriacetic acid (NTA) bound to Ni2+ can be used to reversibly and selectively bind, purify, and fluorescently label His(6)-tagged (N-terminal) glutathione S-transferase (GST) in one step with retention of enzymatic activity. We find binding to be less effective in the absence of the His(6)-tag or Ni2+ ions.