Chemical Biology of Carbonyl Sulfide (COS)
Carbonyl sulfide (COS) is the most prevalent sulfur-containing gas in Earth’s atmosphere, but few studies have investigated its role as an important small gaseous biomolecule. Drawing parallels to the other small important gases NO, CO, H2S, and SO2, COS is poised to play a unique role in living systems. Already detected in living systems, COS has emerged as a potential biomarker for organ rejection and other diseases. Aligned with these opportunities, our group has pioneered the development of COS-releasing small molecules and is at the forefront of leveraging these developed tools to further the investigations of the role of COS in biology. These platforms allow for new chemistry to be developed to access COS-on-demand platforms and provide a first line of investigative tools to expand our understanding of the emerging roles of COS in chemical biology.
Detection, Delivery, and Quantification of Biological H2S
Hydrogen sulfide (H2S), commonly known for its unpleasant rotten-egg smell, is now accepted as an important enzymatically-produced biomolecule that plays important roles in living systems. Joining CO and NO in a class of molecules often referred to as ‘gasotransmitters’, H2S plays important roles diabetes, hypertension, heart failure, inflammation, neurodegeneration. As the biomedical applications of H2S continue to emerge rapidly, the development, refinement, and application of robust, reliable and purpose-inspired chemical tools for studying its multifaceted roles are paramount. Aligned with this need, our group is developing new chemical tools to detect and modulate biological H2S. Such tools include fluorescent, chemiluminescent, and colorimetric methods for H2S detection and quantification as well as slow-releasing H2S donor molecules. These investigations have included collaborations with the Parthasarathy (UO) focused on imaging H2S in live zebrafish as well as with the Kevil group (LSUHSC) focused on different applications of H2S analytical methods. Drawing parallels to the positive impacts of chemical tools for detection, quantification, and delivery of biological NO, we anticipate that these newly-developed chemical tools will enable new investigations into the multifaceted roles H2S in biology and facilitate new discoveries into the roles of H2S in human health and disease.
Bio(in)organic Sulfide Chemistry
Despite the important and diverse roles of H2S in biology, the fundamental chemistry by which H2S exerts its action on discrete biological targets remains uncertain. For example, H2S, persulfides (RSSH) and polysulfide (RSSxR) likely contribute to the complex landscape of H2S chemical biology. Furthermore, HS– is the primary form of H2S under physiological conditions which allows for modulation of water/lipid solubility, nucleophilicity, and reduction potential, but also complicates direct investigations of important reactions with metalloenzymes and interactions with the thiol pool. Motived by these challenges, we use small molecule bioorganic and bioinorganic model systems to investigate how H2S/HS– with transition-metal containing compounds, small sulfur-rich biomolecules, and other reactive sulfur, oxygen, and nitrogen species (RSONS). In addition, we collaborate with the Johnson and Haley groups at the UO to expand investigations into the role of HS– as an overlooked biologically-relevant anion and as a target for synthetic molecular receptors. As a whole, by studying the reactivity of H2S/HS– with simplified molecular architectures, our long-term goal is to develop and use model systems that allow for greater understanding into the fundamental chemistry associated with the storage, translocation, and action of biological H2S.
Self-Assembled Allosteric Catalysts
Inspired by the remarkably complex structures generated from Nature’s simple catalog of assembly components, chemists have devised different strategies to harness molecular self-assembly and develop diverse supramolecular constructs. Similarly, Nature has developed remarkable enzyme catalysts in which catalytic activity can be regulated by co-factor binding, conformational changes, or allosteric regulation. Unlike Nature, synthetic chemists are not constrained to natural amino acids, bioinorganic metal ions, or the requirements to work in water at physiological pH. Although chemists have developed diverse platforms for chemical catalysis, the ability to regulate catalytic activity through external stimuli remains a significant challenge. Motivated by this under-investigated area, we are expand the interface between supramolecular chemistry and catalysis by developing responsive ligand architectures in which catalytic activity is modulated upon guest binding.