Site updated 07.01.2022

Current projects in the ESRG

Biophysics of metal ion coordination
Metal ion coordination in biologal systems has been an area of interest for the ESRG for the past 15 years. We have studied a wide-range of systems using calorimetry and other biophysical methods.

At first glance metal ion coordination in biological systems seems to be a fairly simple idea. However, these complex ion equilibria are not simple in vitro and are amazingly complex in vivo. We are actively developing new methods to explore these processes more accurately, where we aim to understand how binding of metal ions to biomolecules or small molecules to metalloproteins impacts local dynamics. Traditionally we have focused on model systems like human carbonic anhydrase II and a range of non-heme iron proteins. However, recently the ESRG has focused in on three metal-dependent transciption factors from S. pneumoniae

Model of protein structure
Graphical abstract associated with recent paper
K. McConnell, N. Fitzkee, and J. Emerson have reported their efforts to understand how metal ions impact conformational dynamics in a model protein system in Inorganic Chemistry. This marks the group's first effort to look beyond metal ion binding thermodynamics and into how the protein is changing. 
NIH logo
The research collaboration between Emerson and Stokes has been selected to join the National Institute of Health’s Center of Biomedical Research Excellence in Pathogen Host Interactions Program at Mississippi State University. Their project entitled "Conformational dynamics of the zinc(II) binding site of AdcR and its role in DNA binding" will receive $830K over the next 2.5 years to support this work.

First row transition metal catalysts for novel reactions
     In the Emerson Stokes Research Group, we are working towards designing new catalysts for novel organic transformations. This includes projects aimed at developing new ligands for organometallic complexes, utilizing first-row transition metal catalysts for C-N bond forming reactions, and the efficient, low-cost modifications of known bioactive molecules. Our ligand design has involved both N-heterocyclic carbenes (NHCs) and phenanthroline-based architectures for the arylation of small molecules and biomolecules. We are interested in exploring the mechanism and redox chemistry involved in many of these catalytic processes as well as understanding the spectroscopic changes that emerge from catalyst turnover. In addition, some of our research focus is on devising new methods of heterogeneous and homogeneous catalysis including the use of “soft materials” such as proteins, DNA, and lipids as flexible media to support novel transformations.
crystal structure of [Cu(phen)(OTf)]+ and DFT derived HOMO
M. Sharma and co-authors have reported their efforts to study phenol generation from aryl boronic acids in Chemistry. This contribution showcases a tridentate N-C-N copper(II) NHC pincer complex.
Phenol generation scheme with Cu(II) NHC complex.
J. Cope and co-authors have reported a paper characterizing our first tetradentate copper(II) N-heterocyclic carbene complex in Organometallics. This marks the group's first new copper(II) complex that shows good CEL chemistry.
copper(II) NHC crystal structure

O2 activation and interesting biological transformations
Since the start of the ESRG, we have been interested in novel reactions catalyzed by (metallo)enzymatic systems. From C-H bond activation in non-heme proteins to oxidative C-C bond cleavage Nature has interesting and unique ways of catalyzing reactions, and it is our hypothesis that these transformations can be used to catalyzed industrial processes in a sustainable fashion. 
Our most recent project is focused on pyrrolnitirn biosynthesis, where there are 4 dioxygen-dependent oxidative steps that convert tryptophan into pyrrolnitirn. 
pyrolintirn biosynthesis pathway
Congratulations to Mahmuda Akter for completing her MS thesis projects on PrnA! Her efforts have moved this project forward and provided a foundation for further exploration of pyrolnitirin biosynthesis and related organic transformations. 
MSU campus photo