Determination of the Metal-Binding Cooperativity of Wild-Type and Mutant Calbindin D9K by Electrospray Ionization Mass Spectrometry
Rapid Communications in Mass Spectrometry
Since the initial reports showing the ability of electrospray ionization mass spectrometry (ESI-MS) to study intact noncovalent biomolecular complexes, an increasing number of uses for this technique in studying biochemical systems is emerging. We have investigated the ability of ESI-MS to characterize the metal-binding properties of calcium (Ca2+) binding proteins by studying the incorporation of Ca2+ and cadmium (Cd2+) into wild-type and mutant calbindin D9K. ESI-MS showed that wild-type calbindin D9K binds two Ca2+ ions with similar affinities while the binding of two Cd2+ ions is sequential, as is the binding of the two Ca2+ or Cd2+ ions to the N56A mutant of calbindin. The binding of Ca2+ to the wild-type protein was clearly seen to be cooperative. These results demonstrate the potential efficacy of ESI-MS to discriminate between cooperative and independent site metal binding to metalloproteins.
Cadmium, calbindins, calcium, mass spectrometry, metals, mutation, nerve tissue proteins, protein binding
Chazin, Walter and Veenstra, Timothy D., "Determination of the Metal-Binding Cooperativity of Wild-Type and Mutant Calbindin D9K by Electrospray Ionization Mass Spectrometry" (1999). Pharmaceutical Sciences Faculty Publications. 534.