Award: OCE-1457870

We studied how proteins evolve in oceanic water columns as they age, because proteins are the major component of organic nitrogen. These proteins are created largely by phytoplankton, and then transform as they progress through decay and various food chains. In conjunction with colleagues at the University of Washington, we measured both the availability of these proteins to consumers, such as bacteria, and the changes in composition. Analyses were conducted after enzymatic digestion of the material, using enzymes that break up long peptide sequences into shorter ones, and then measuring the amounts and the amino acid sequences. Our studies were conducted on materials from both laboratory experiments and sediment traps in the ocean. Upon experimental decay of phytoplankton in the laboratory, we found decreases in the amounts of protein digestible by enzymes, as colonizing bacteria consumed the original phytoplankton. Some differences were found between behavior of enzymatically available proteins and total nitrogen of the experimental materials. Decreases in amounts accompanied changes in amino acid sequence, assessed using novel forms of proteomic analysis. These results will aid in future identification of the fate of proteins in the ocean using these proteomic approaches. Conference presentations have been made, and a scientific publication is planned. Two graduate students received support as part of this project. Last Modified: 07/31/2018 Submitted by: Lawrence M Mayer