The Metals in the Biological Periodic System of the Elements: Concepts and Conjectures.

Wolfgang Maret

doi:10.3390/ijms17010066

Abstract

A significant number of chemical elements are either essential for life with known functions, or present in organisms with poorly defined functional outcomes. We do not know all the essential elements with certainty and we know even less about the functions of apparently non-essential elements. In this article, I discuss a basis for a biological periodic system of the elements and that biochemistry should include the elements that are traditionally part of inorganic chemistry and not only those that are in the purview of organic chemistry. A biological periodic system of the elements needs to specify what “essential” means and to which biological species it refers. It represents a snapshot of our present knowledge and is expected to undergo further modifications in the future. An integrated approach of biometal sciences called metallomics is required to understand the interactions of metal ions, the biological functions that their chemical structures acquire in the biological system, and how their usage is fine-tuned in biological species and in populations of species with genetic variations (the variome).

Highlights

Many scientific disciplines address which chemical elements are present in organisms and whichMany scientific disciplines address which chemical elements are present in organisms and which functions they have
Trace element research matured with advances in analytical chemistry and instrumentation and provided evidence for additional essential elements, the metal ions of iron (Fe), zinc (Zn), manganese (Mn), copper (Cu), cobalt (Co) in the form of vitamin B12, molybdenum (Mo) and the non-metals selenium (Se) and iodine (I)
Mg complexes are usually stronger than Ca complexes, Ca is stabilized over Mg in biology by using additional ligands and coordination numbers higher than six

Summary

Introduction

Trace element research matured with advances in analytical chemistry and instrumentation and provided evidence for additional essential elements, the metal ions of iron (Fe), zinc (Zn), manganese (Mn), copper (Cu), cobalt (Co) in the form of vitamin B12 , molybdenum (Mo) and the non-metals selenium (Se) and iodine (I) They are in the mg range, except for iron and zinc which are 2–5 g and strictly speaking not trace elements. Mg complexes are usually stronger than Ca complexes, Ca is stabilized over Mg in biology by using additional ligands and coordination numbers higher than six This stabilization is necessary because Ca2+ has been adopted as a cellular signalling ion controlling many processes. Whereas Ca2+ activates many processes, Zn2+ seems to be primarily an inhibitory ion and due to its preference for different ligands and different coordination environments it targets other sets of proteins [3]

The Essential Elements

The Non-Essential Elements

Findings

Conclusions