The rapid and modular generation of molecular diversity is key to the search for new chemical functions. One particularly useful functional group is the halogen (X = Cl, Br, I), which enables many selective and effective downstream strategies for creating structural complexity. In this regard, halogenase enzymes have provided an important and complementary approach to synthetic catalysts for regio- and stereoselective introduction of a halogen substituent on a complex scaffold, which remains challenging to achieve. While many families of halogenases exist, the radical halogenases provide the greatest potential for reaction diversity, as they are competent to replace unactivated C-H bonds with a halogen unlike those that operate by electrophilic or nucleophilic mechanisms. However, the substrate scope of these enzymes has been limited to date to either protein-bound substrates or large late-stage natural product intermediates. Our group has discovered a new clade of radical halogenases capable of reacting with small molecule substrates. We now seek to take advantage of this discovery to develop new tools for in vitro and in vivo synthesis.
Specific aims of this proposal include: (i) elucidating the structure and mechanism of these new radical halogenases, which will provide important insight into their engineering, (ii) investigating and engineering selectivity in halogenases, and (iii) developing applications for halogenases to produce new amino-acid based products.
(Public Health Relevancy Statement) The creation of new chemical diversity has long driven the discovery and development of compounds to treat a broad range of human health conditions. Our long-term goal is advance our ability to produce novel structures by working at the interface of biological and chemical catalysis. In this proposal, we seek to identify and generate new diversity in radical halogenases, which are capable of installing the particularly useful halogen handle on small molecules at unactivated positions with regio- and stereo-selectivity to enable rapid generation of new and complex small molecule targets.
