Confining Metal Complexes within Protein Hosts: Models for Metalloprotein Active Sites

This research will develop methods to model active sites in metalloproteins for the purpose of
determining fundamental structure-function relationships for how proteins activate dioxygen, a
process that strongly impacts human health and aging. Artificial metallproteins will be prepared
utilizing biotin-streptavidin technology as a tool to ensure specific and reproducible placement
of synthetic metal complexes within protein hosts. This approach is proposed to be an effective
method to model key properties of the active sites in native metalloproteins, including site
isolation of species, regulation of the primary coordination sphere, and control of the
microenvironments around the metal complexes. One glaring weakness of many biomimetic
systems is their limited ability to regulate the microenvironments that surround metal centers.
No chemical system operates in isolation without interacting with its local environment. There is
a growing body of evidence from structural biology that the microenvironment, a space around
metal complexes that comprises the secondary coordination sphere, has profound effects on
protein function that ranges from modulation of physical properties to delivery of reactants and
removal of products.
It is our contention that the greater regulation of microenvironments will lead to better
understanding of protein function. It is further maintained that the benefits gained from
fundamental analyses as proposed in this application extend well beyond improvements in
selectivities/efficiencies at the molecular level – they are transformative for all types of
platforms, providing the requisite information that is still missing for the development of
highly functional systems.
We propose an approach for preparing artificial metalloproteins that allows for the confinement
of synthetic complexes within protein hosts to regulate both the primary and secondary
coordination spheres about the immobilized metal centers. The ability to regulate these
coordination spheres within a protein will produce systematic structure-function relationships
that will lead to an improved understanding of chemical processes that are directly linked to
human health.

Grant Number: 5R01GM120349-08
NIH Institute/Center: NIH
Principal Investigator: Andrew Borovik