Although large amounts of carbon are stored in the oceans as dissolved organic matter (DOM), the complexity of this heterogeneous pool has meant that little is known about the high molecular weight organic matter at the molecular level, and this lack has hindered a more detailed understanding of the mechanisms that control its cycling. Scientists from the University of West Virginia and from the University of Puerto Rico have teamed up to study an important component of DOM, the dissolved proteins in the ocean. Although only a small fraction of the DOM, proteins are, however, a primary component of the dissolved organic nitrogen pool that arises from processes such as cell lysis or excretion. They will take advantage of the dramatic improvements in proteomic analysis to sequence and identify marine proteins using state-of-the-art mass spectrometric analysis. Intact proteins will be analyzed with Fourier transform mass spectrometry to access the complexity of protein bands separated by gel electrophoresis. The reliability and specificity of peptide tags obtained through de novo sequencing will hence be improved. Direct database matching and homology searching should yield important clues to the sources of dissolved proteins. The data will be searched for evidence suggesting the presence of post-translational protein modifications. Identified modifications will be characterized to determine if they are common biological modifications or if they appear to be the result of abiotic processes. Successful transfer of these techniques to the ocean will open the way for resolution of longstanding issues concerning the sources and changes in organic nitrogen, an important reservoir of nitrogen for marine life.
In terms of broader impacts, results from this study will begin to apply the rapidly maturing technology of proteomics to the chemistry of organic nitrogen in the oceans, leveraging knowledge from the burgeoning genomic sequences of marine organisms. A graduate student, and a postdoctoral fellow with training in Chemical Oceanography, will be trained in these new techniques as part of this study.
