Resolution of a paradox by native mass spectrometry: facile occupation of all four metal binding sites in the dimeric zinc sensor SmtB

摘要

The predominant species of the cyanobacterial metalloregulatory protein SmtB as observed by ESI-MS is a dimer with all four zinc binding sites occupied. Cellular biochemistry relies heavily upon the presence of a range of metal ions, including iron, zinc and copper. Although they are vital once bound to proteins, providing either structural or functional roles, the concentration of free ions has to be tightly regulated by homeostatic systems due to their inherent toxicity at high concentrations.