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Project Progress

Biomimetic Cluster Synthesis: Bridging the Structure and Reactivity of Biotic and Abiotic Iron-Sulfur Motifs

(Douglas, Strongin, & Young)

Minerals are thought to act as templates for the organization of macromolecular structures essential for the development of life. The interface between mineral surfaces and early biological molecules may have played a key role in early life. Today, soft organic biological interfaces can also direct the organization of hard inorganic materials, in almost all living systems through biomineralization. In exploring the hard-soft interface we have demonstrated a direct templating interaction between a virus capsid and an inorganic minerals — both oxide and sulfide minerals that are important in the origin of life context. Proteins that form cage-like quaternary structures such as ferritins and viruses, define constrained reaction environments where mineral deposition can be directed, through hard-soft interactions, and sequestered for the exterior environment. We have directed the synthesis of protein cage encapsulated metal sulfides either through a direct synthetic method or via the transformation of a preformed metal oxide material. Iron, titanium, cobalt, molybdenum, and lanthanide oxides have been synthesized within the confines of these protein cage architectures. The iron and molybdenum oxides can be transformed into corresponding sulfide minerals through a corrosion/reprecipitation process that is confined to the interior of the cage and does not involve the bulk medium. These minerals are active catalysts undergoing photochemical redox transformations potentially important to understanding the origin of life.

A detailed understanding of virus structure-function relationship may serve as a model for the evolution of early life. Viruses are highly organized supramolecular structures and are some of the best examples of complex structure-function relationships. Viruses are perhaps the precursors to living systems — highly organized and complex macromolecules that act in concert to carry out their overall function in a number of steps. For those studying issues surrounding the origin of life, there is significant interest in understanding the interactions between hard inorganic minerals and soft organic structures that are synonymous with life.