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X-RAY RUNS: Apply for Beamtime

2017  Nov 1 - Dec 21
2017  Proposal/BTR deadline: 9/1/17

Talk Abstracts

 

 
"Oriented 2D Covalent Organic Framework Thin Films on Single-Layer Graphene"

John Colson
Cornell University - Dichtel Group

Abstract:  Covalent organic frameworks (COFs), in which molecular building blocks form robust microporous networks, are usually synthesized as insoluble and unprocessable powders. We have grown two-dimensional (2D) COF films on single-layer graphene (SLG) under operationally simple solvothermal conditions. The layered films stack normal to the SLG surface and show improved crystallinity compared with COF powders. We used SLG surfaces supported on copper, silicon carbide, and transparent fused silica (SiO2) substrates, enabling optical spectroscopy of COFs in transmission mode. The synthetic flexibility of the building blocks enables COF films with varying pore sizes to be grown on SLG. A number of these are of interest for organic electronic devices for which thin-film formation is a prerequisite for characterizing their optoelectronic properties.

 

 
"Structural Studies of Multidomain Enzymes Involved in Natural Product Synthesis"

Andrew Gulick
Hauptman-Woodward Medical Research Institute and University of Buffalo

Abstract:  Many bacteria produce small peptides using a family of modular enzymes called Non-Ribosomal Peptide Synthetases (NRPSs). Each NRPS module contains, at a minimimum, three domains: a carrier protein, an adenylation, and a condensation domain. Together, these domains are responsible for the incorporation of a single amino acid into the peptide. The internal carrier protein domain serves as an anchor for the amino acids and nascent peptide during synthesis. Amino acids are selectively activated by the adenylation domain and covalently loaded onto the pantetheine cofactor of the carrier domain. An intervening condensation domain then catalyzes peptide bond formation between two amino acids on the carrier protein domains of adjacent modules. Crystallization of the multidomain NRPS proteins is hindered by the inherent flexibility of these proteins. While numerous structures exist of the isolated domains, structures of functionally relevant multidomain complexes are rare. We will present a novel structure of a multidomain NRPS protein that was obtained through a combination of protein engineering and rational inhibitor design.

 

 
"Oriented 2D Covalent Organic Framework Thin Films on Single-Layer Graphene"

Gregory Van Duyne
University of Pennsylvania School of Medicine and Howard Hughes Medical Institute

Abstract:  Small angle x-ray scattering (SAXS) provides information about the size and shape of a macromolecule in solution and when combined with existing structural data for the components of a macromolecular complex can provide experimental restraints to test specific models. We have been using SAXS in conjunction with other biophysical methods to understand the solution structures of retroviral integrase-DNA assemblies, large serine recombinase-DNA complexes, group II introns, and the SMN complex responsible for spliceosomal snRNP assembly. In each case, SAXS experiments have led to important insights into the nature of the oligomeric states and shapes of these macromolecular complexes. We will present an overview of these results, with an emphasis on experiments performed at the CHESS G1 and F2 beam lines.