Beyond the Mineral Sorptive Protection Hypothesis: Protein Preservation in Marine Systems via Formation of High-Molecular Mass Aggregates

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ABSTRACTOCE-0136631The focus of this research is a better understanding the mechanisms of the preservation of high molecular weight (~ 106 D) nitrogen rich macromolecular proteinaceous material in marine sediments and in the water column. Some of these molecules persist in sediments that are thousands of years old. Proteins, as energy rich biochemical substrates, are normally rapidly degraded in the environment by a range of high affinity bacterial proteases and enzyme systems, so the persistence of protein-like macromolecules for long periods of time in substrate (N) poor sediments remains inadequately explained. Preservation through selective sorptive protection in inaccessible sediment mesopores, structural modification such as glucosylation, condensation or complexation, aggregation and encapsulation in biochemically resistant materials such as membrane or cell wall components are some of the suggested mechanisms. Possibly all of these may operate to some extent. This study sets out to investigate range of non-covalent interactions entered into by polypeptides on mineral surfaces and or encapsulation of representative proteins into refractive biopolymers as potential important controlling factors resulting in preservation of such molecules. A series of laboratory manipulation experiments and protein characterization techniques, using a wide range of analytical tools, and applied to sedimentary and particulate associated organic matter will be used to examine support for these preservation mechanisms. The rates of turnover of carbon compounds in the shallow and deep seas is of importance to our understanding of the ocean's carbon cycle.