App Note I January 22, 2016

Real-time measurement of nickel ion chelation kinetics

Nitrilotriacetic acid (NTA) is a common chelating agent, which forms coordination compounds with metal ions (chelates) such as Ni2+, Cu2+ and Co2+. It is primarily used for the purification and immobilization of His-tagged proteins, which are captured by NTA-Ni2+ chelates bound to solid supports. The loading of NTA with nickel ions is an essential step for the activity of the chelate. Thus, we determined the association rate of Ni2+ to NTA by using the Fluorescence Proximity Sensing measurement mode. Further we investigated the stability of the chelate against a competitive chelator, EDTA. Such information is required for the research applications involving His-tag capture and industrial protein purification methodologies.