natural organic matter; hydrogen peroxide; indirect photolysis; hydroxyl radical; amino acids; singlet oxygen; direct phototransformation; proteins; photochemistry; reactive oxygen species
Manfrin Alessandro, Borduas-Dedekind Nadine, Lau Kate, McNeill Kristopher (2019), Singlet Oxygen Photooxidation of Peptidic Oxazoles and Thiazoles, in The Journal of Organic Chemistry
, 84(5), 2439-2447.
Egli Christine M., Janssen Elisabeth M.-L. (2018), Proteomics Approach To Trace Site-Specific Damage in Aquatic Extracellular Enzymes During Photoinactivation, in Environmental Science & Technology
, 52(14), 7671-7679.
Chu Chiheng, Stamatelatos Dimitrios, McNeill Kristopher (2017), Aquatic indirect photochemical transformations of natural peptidic thiols: impact of thiol properties, solution pH, solution salinity and metal ions, in Environmental Science: Processes & Impacts
, 19, 1518-1527.
Chu Chiheng, Erickson Paul R., Lundeen Rachel A., Stamatelatos Dimitrios, Alaimo Peter J., Latch Douglas E., McNeill Kristopher (2016), Photochemical and Nonphotochemical Transformations of Cysteine with Dissolved Organic Matter, in Environmental Science & Technology
, 50(12), 6363-6373.
Lundeen Rachel, Chu Chiheng, Sander Michael, McNeill Kristopher (2016), Photooxidation of the Antimicrobial, Nonribosomal Peptide Bacitracin A by Singlet Oxygen under Environmentally Relevant Conditions, in Environmental Science & Technology
, 50(16), 8586-8595.
Chu Chiheng, Lundeen Rachel, Sander Michael, McNeill Kristopher (2015), Assessing the Indirect Photochemical Transformation of Dissolved Combined Amino Acids through the Use of Systematically Designed Histidine-Containing Oligopeptides, in Environmental Science & Technology
, 49(21), 12798-12807.
Amino acid-based biomolecules are central building blocks of life and of key importance in the biogeochemistry of aquatic systems. In these systems, amino acids are susceptible to oxidation by photochemically generated reactive oxygen species. Despite the importance of environmental photochemical degradation of proteins, peptides and amino acids, there remain few systematic studies on this topic. This proposal aims to fill gaps in our knowledge regarding the environmental photochemistry of amino acid-based biomolecules in aquatic systems.The specific objectives of this proposal are to (1) Characterize the photochemistry of freely dissolved cysteine and cystine; (2) To delineate the environmental photochemistry of selected amino acids found in non-ribosomal peptides (NRPs) and ribosomally synthesized and posttranslationally modified peptides (RiPPs); (3) To determine the effect of zinc binding on the photooxidation of histidine and cysteine; and, (4) To assess photoinactivation of extracellular enzymes in relation to site-specific oxidation of AA residues. These objectives each represent current blind spots in our understanding of the photochemical fate of amino acid-based biomolecules. They also share unifying methodological concepts for the photochemical procedures and analysis and are interconnected as advancements in one project area will facilitate our studies on the others (e.g. going from cysteine photochemistry over Cys-zinc complexes to (metallo-)enzyme photoinactivation). The work plan is organized into four Subprojects that will be carried out by three starting PhD students (3 x 3 years) and a senior PhD student (1 year). The expected scientific outcome is an improved understanding of amino acid photooxidation in surface waters at the molecular level. Specifically, this project will illuminate important areas of the environmental chemistry of amino acids that have mostly been ignored, including the wide-open area of non-canonical NRP and RiPP amino acids, metal-amino acid complexes, and intact enzymes in natural water samples. This understanding promises to impact the larger scientific community, including biogeochemists studying sulfur and nitrogen element cycling, environmental chemists looking at peptide-based water contaminants, and ecologists interested in the role of extracellular enzymes in nutrient acquisition. In addition, we expect to make methodological advances that will aid in the study of enzymes and other biomacromolecules in natural waters in the future. The proposed project will also achieve education outcomes including four PhD students and six related master thesis students. Numerous synergisms are expected to arise from the parallel projects on distinct yet closely related topics.