Use of mass spectrometry techniques for the characterization of metal bound to proteins (metallomics) in biological systems

The need to determine the individual chemical species (speciation), especially when they are known to have a differential action and behavior in relation to toxicity, mobility, or bioavailability, is discussed. The analytical approaches for small mass metal species characterization, as well as sample treatment and storage, is now well established on the basis of chromatographic-atomic detector combinations. The description of a new scenario centered on endogenous and exogenous metallic species in biological systems, bioactive macromolecules, such as proteins, DNA restriction fragments, phytochelatins, metallothioneins and others is fulfilled. Many of these systems are not well known at present and require a new generation of analytical tools that substitute the traditional atomic detectors based in the use of photons (atomic absorption spectrometry (AAS), flame photoionization detector (FPD), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), atomic fluorescence spectroscopy(AFS)) by mass detectors (mass spectrometry (MS) and inductively coupled plasma-mass spectrometry (ICP-MS)) that characterize ions. The photonic analytical tool is now being substituted by the ionic paradigm. Many cases related to biological molecules involving proteins and multiprotein systems, in which metals frequently participate (metallomics) are described, and a generic metallomics analytical approach is proposed for the identification and quantification of metalloproteins, and other metallomacromolecules present in life systems, on the basis of three experimental focuses: (i) a separation technique—selectivity component; (ii) an element-high sensitivity detector—sensitivity component; and (iii) a molecule-specific detector, generally based on mass spectrometry—structural component. This multiplexed analytical approach brings together both elemental and molecular detectors for easy metalloproteins identification. Finally, the possibilities of the metallomics approach in the environmental, food and clinical fields are considered on the basis of a number of reported studies.