Life and death metal

First there was genomics, the study of all genes and their sequences, then there was transcriptomics, the expression of those genes via RNA. Next came proteomics, protein expression closely followed by metabolomics, the study of the metabolic products and pathways enabled by the proteins. Now, atomic spectroscopy could open up research into yet another "omic" - metallomics, the study of the whole gamut of metallic elements and species in an organism.

Writing recently in the Journal of Analytical Atomic Spectroscopy (JAAS) David Koppenaal of Pacific Northwest National Laboratory in Richland, Washington and Gary Hieftje of Indiana University in Bloomington explain how metallomics, a term coined in the early 2000s, might in one sense be considered nothing more than a new name for bioinorganic chemistry. As such many of the analytical skills developed within that field could be just as application to the study of metals and metal species, their interactions, biochemical reactions, and functions in biological systems. In another sense, metallomics could represent a challenge to which atomic spectrometry might rise and emerge as a "vibrant scientific discipline".

There is no organism on earth that does not rely in some way on metallic elements and so atomic spectrometry could readily play a major part in improving our understanding of biology at the elemental level. Almost every member of the periodic table is present in at least one organism in one form or another, whether for its benefit, as a protective measure, or as a poison. Metalloproteins and metalloenzymes are vital biochemical commodities to all species and approximately thirty percent of all proteins contain metals.

It is important to recognise the fact that in most biological systems, the form in which any particular metal exists can be very diverse "from free ions to metalloproteins, from tightly bound species to loosely held complexes", and even metal aggregates held within nanoscopic capsules. Moreover, the researchers point out that the range of concentrations for metallic species in living things is very large too, spanning fourteen orders of magnitude. This, they point out is "sure to tax any instrumental system."

One final issue that taxes the analytical scientist again and again when it comes to dissecting an organism at the metallomic level is the bewildering array of matrices within which any given metal species might be found. Various conventional methods, such as LC-ICP-MS and CE-ESI-MS are currently providing new metallomics insights, but as new techniques come online, so new discoveries will be made. Atomic spectrometry is perfectly suited to rise to the challenge. "It is certainly apparent that metallomics is a vogue topic, and one that can help assimilate atomic spectrometry into the biological sciences in a fully meaningful way," Koppenaal and Hieftje say.