Metal compounds abundant in Early Earth are thought to play an important
role in the origins of life. Certain iron-sulfur minerals, for example,
are proposed to have served as primitive metalloenzyme cofactors for
their ability to catalyze organic synthesis processes and facilitate
electron transfer reactions. An inherent difficulty with studying the
catalytic potential of many metal compounds is the wide range of data
and parameters to consider when searching for individual minerals and
ligands of interest. Detecting mineral-ligand pairs that are
structurally analogous enables more relevant selections of data to
study, since structural affinity is a key indicator of comparable
catalytic function. However, current structure-oriented approaches tend
to be subjective and localized, and do not quantify observations or
compare them with other potential targets. Here, we present a
mathematical approach that compares structural similarities between
various minerals and ligands using molecular similarity metrics. We use
an iterative substructure search in the crystal lattice, paired with
benchmark structural similarity methods. This structural comparison may
be considered as a first stage in a more advanced analysis tool that
will include a range of chemical and physical factors when computing
mineral-ligand similarity. This approach will seek relationships between
the mineral and enzyme worlds, with applications to the origins of life,
ecology, catalysis and astrobiology.