Titanium, although being undeniably abundant, relatively cheap, and meeting all criteria necessary for biological activity, has been assumed to be irrelevant in biological systems and underused in biological roles due to its susceptibility to hydrolytic precipitation. Outside of aqueous solution, however, titanium has demonstrated various uses, such as solar energy, catalysis, and TiO<sub>2</sub> materials – which are used as coloring and fillers in various products. Nature has found ways to work around this hydrolysis by utilizing ligands that bind and stabilize these metals, which keeps them soluble in aqueous solutions.  Titanium has also been shown to interact with many biological molecules, such as vitamin C and transferrin. Although many proteins have been shown to bind to titanium compounds, no native titanium binding protein or enzyme is known. However, these uses show that there is a multitude of possible applications for titanium in aqueous solutions, if control can be maintained. For example, the development of titanium biocatalysts has potential to eliminate the necessity for harsh solvent conditions that are currently used in industrial titanium catalysis. The coordination residues in the binding sites of naturally occurring metal binding proteins offer insight for studying how they can prevent unwanted hydrolysis, and the known Due Ferri single chain (DFsc) protein scaffold provides a starting structure to test the potential of titanium enzymes. This protein was bound to titanium, as evidenced by circular dichroism (CD) spectroscopy, which shows that the DFsc protein increases in alpha-helical character upon addition of titanium, consistent with metal binding, and a competitive binding assay against cobalt. This Ti-bound protein was then tested for its ability to function as a hydrolytic mini-metalloenzymes (MMEs) in the cleavage of DNA. Enzymatic activity of this titanium MME is modest, but is the first example of a soluble titanium enzyme. Modification of the protein active site will potentially enhance both titanium binding, and hydrolytic activity.<br/>

DNA cleavage with a titanium mini-metalloenzyme

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.