Research Highlights
Graduate student Nick Polizzi and collaborators in Beratan's lab have built a theoretical model to describe how charge flows through bacterial appendages, known as pili. Pili are implicated in the exchange of electrons between living organisms and inorganic substrates. These studies may assist in the design of future semi-biological solar cells that would convert sunlight into liquid fuels, with the help of photovoltaics that are "plugged" into living bacteria. Details appear in: Faraday Discussions, 155, 43-62 (2012).
Recent work from the Craig lab reports a functional group that grows longer in response to applied machincal forces, a response that can subsequently be reversed by shining light on the sample. Read more about the new mechanophore and its properties here.
Postdoctoral associate Sam Banerjee and Dr. Alvin Crumbliss, with collaborators from the Duke Marine Lab (C. Bonaventura and R. Henkens) and NIH (A. Alayash), published an article in a recent issue of Antioxidants & Redox Signaling that features an in-print forum on Redox Reactions of Hemoglobin: Mechanisms of Toxicity and Control (Antioxid. Redox Signal. (2013) 18, 2298-2313). Banerjee, Crumbliss and co-workers explore the molecular level processes that control the redox and O2-binding functions of hemoglobin that allow organisms with significantly different physiological demands to exist in a wide range of environments. For example, elucidating these molecular controls helps to understand the symbiotic relationships that allow L. pectinata clams to live in high sulfur content muds in mangrove swamps, how dolphins can adapt to deep dives, how sickle cell hemoglobin confers resistance against malaria infection, how safe and effective blood substitutes can be developed, and how organisms deal with nitrosative and oxidative stress associated with blood pressure regulation and ageing.
The Widenhoefer group has recently reported the gold(I)-catalyzed stereoconvergent, intermolecular enantioselective hydroamination of chiral, racemic 1,3-disubstituted allenes, which represents the first example of enantioselective intermolecular allene hydroamination. The method effectively forms N-allylic carbamates, which are important chiral building blocks, with high regio- and diastereoselectivity and with up to 92% ee. The editors of Angewandte Chemie have designated it a “hot paper”. Butler, K. L.; Tragni, M.; Widenhoefer, R. A. Abstract available here.
The Hong lab has recently reported the total synthesis of (+)-dactylolide in 19 steps for the longest sequence from commercially available 1,3-dithiane with an overall yield of 1.4%. The total synthesis of (+)-dactylolide was accomplished through the 1,6-oxa conjugate addition reaction of a 2,4-dienal for the facile synthesis of the 2,6-cis-2-(4-oxo-2-butenyl)-tetrahydropyran subunit, the umpolung alkylation reaction of a cyanohydrin, and the NHC-catalyzed oxidative macrolactonization reaction for the synthesis of the 20-membered macrocyle of the natural product. K. Lee et al. Angewandte Chemie.
How does nature handle copper, an essential metal that is also potentially toxic? To find out, check out this Franz lab review article, which was featured on the February cover of the Journal of Inorganic Biochemistry.
The Wiley lab has developed a scalable synthesis to produce long (>20 um), thin (<60 nm), well-dispersed copper nanowires, as well as their scalable coating onto a plastic substrate to create flexible, transparent conducting films with a sheet resistance of 30 Ω sq-1 at a transmittance of 85%. These values make films of copper nanowires among the highest-performing, solution-coatable alternatives to the dominant transparent conductor, indium tin oxide (ITO). Copper nanowire films can carry high currents (>500 mA cm-2), were stable in air at room temperature for over one month, were 80% more transparent than ITO in the near-infrared and, unlike ITO, could be bent 1000 times without any degradation in their properties. This article has been published in Advanced Materials, and has been highlighted by the Duke University News.
Recently reported in Angewandte Chemie, the Chilkoti and McCafferty groups at Duke have collaborated to discover a 'three-in-one' facile method for the chromatography-free purification of recombinant proteins and optional, site-specific conjugation of the protein to a small molecule. The investigators have prepared a first-in-class recombinant expression and purification system that combines elastin-like polypeptide sequences (ELPs), which transition between soluble and insoluble phases with changes in temperature, with staphylococcal sortase SrtA transpeptidase mediated fusion protein removal. Because sortase transpeptidase cleaves via a stable thioester enzyme-acyl intermediate, interception by nucleophilic small molecules can produce terminally-labeled proteins, as well as providing reactive groups for additional ligation chemistry to recombinant protein and peptide fragments.