Noncovalent Interactions Involving Group 6 in Biological Systems: The Case of Molybdopterin and Tungstopterin Cofactors

In this study we propose to coin the term Wolfium bond (WfB) to refer to a net attractive force (noncovalent interaction) between any element of group 6 and electron donor atoms (neutral molecules or anions) and to differentiate it from a coordination bond (metal-ligand interaction). We provide evidence of the existence of this interaction by inspecting the X-ray crystal structure of proteins containing Molybdopterin and Tungstopterin cofactors from the Protein Data Bank (PDB). The plausible biological role of the interaction as well as its physical nature (antibonding Wf-Ligand orbital involved) are also analyzed by means of ab initio calculations (RI-MP2/def2-TZVP level of theory), Atoms in Molecules (AIM), Natural Bond Orbital (NBO) and Noncovalent Interactions plot (NCIplot) analyses.

Automated summary

In this study, we propose the term Wolfium bond (WfB) to describe the net attractive force between group 6 elements and electron donor atoms. By analyzing the X-ray crystal structures of proteins and conducting ab initio calculations, we provide evidence for the existence of this interaction and explore its potential biological role and physical nature.