Chemical Physics and Physical Chemistry

Physical Chemistry Seminar Dr. Thomas Rizzo (École Polytechnique Fédérale de Lausanne)

Thu, 2017-10-12 13:00 - 14:00
Speaker: 

 

Host Lester

Title Cryogenic spectroscopy of biomolecular ions: From homo-chiral selection to carbohydrate analysis

 

Abstract While mass spectrometry (MS) has been a workhorse tool for the detection and identification of biological molecules, it is limited in its ability to determine 3-dimensional structure. When MS is combined with ion mobility spectrometry (IMS), which determines the orientationally averaged cross section of ions as they are dragged through a static gas, one gains valuable information on the molecular shape, albeit not the precise 3-D structure. On the other hand, adding a vibrational spectroscopic dimension to MS provides a fingerprint that is directly related to an ion’s precise conformation, particularly when measurements are performed at cryogenic temperatures. In our laboratory, we have constructed a hybrid instrument that combines all three techniques – MS, IMS, and cryogenic ion spectroscopy (CIS). This multidimensional approach allows one to leverage the advantages of each technique for augmenting the information available from each method separately. This talk will focus on two specific applications of cryogenic ion spectroscopy, combined in one case with MS and in the second case with IMS-MS. In the first, we use it to unravel the mystery of the serine octamer. Clusters of the amino acid serine show an extremely strong “magic number” at the octamer, which is also strongly homo-chiral, and this has caused some to speculate as to its role in chiral selection. However, the structure that gives rise to this selective behaviour has never been determined. We use cryogenic ion spectroscopy coupled to mass spectrometry, together with high-level quantum chemical calculations, to solve this mystery. The second application combines cryogenic ion spectroscopy with IMS-MS to determine the primary structure of oligosaccharides, or glycans. Glycosylation of proteins is one of the most common post-translational modifications, and the attached glycans play a fundamental role in all biological systems. Glycans attached to proteins or lipids are present at the surface of almost all cells and mediate cell-to-cell recognition and signaling, for example. They largely govern the interaction of cells with bacteria and viruses and are central to immune response and inflammation. Despite their importance, glycan structure is notoriously difficult to determine, because of the many different types of isomerization that can exist. We have shown that cryogenic vibrational spectroscopy is exquisitely sensitive to even the slightest change in structure and can easily distinguish all types of glycan isomerization. This talk will present our initial results applying this approach and explain how it could lead to high-throughput sequencing of glycans.

Location: 

Carol Lynch Lecture Hall, Chemistry Complex

Attached Document: 
inquires please contact Rosa M. Vargas rvargas@sas.upennn.edu

Physical Chemistry Seminar Dr. Jin Wang(Stony Brook University)

Thu, 2017-10-26 13:00 - 14:00
Speaker: 
Host:Saven
Location: 

Carol Lynch Lecture Hall, Chemistry Complex

Title: Landscape and Flux Theory of Nonequilibrium Physical and Biological Systems

 

Physical Chemistry Seminar Dr. Reshef Tenne (Weizmann Institute- Israel)

Thu, 2017-10-05 13:00 - 14:00
Speaker: 
Host: Nitzan
Location: 

Carol Lynch Lecture Hall , Chemistry Complex

Attached Document: 

Title: Inorganic nanotubes and fullerene-like nanoparticles from 2D compounds at the crossroad between materials science and nanotechnology and their applications

Physical Chemsitry Seminar Dr. Frances Hellman (Univerisity of California- Berkeley)

Thu, 2017-10-19 13:00 - 14:00
Speaker: 
Host: Fakhraai
Location: 
Lynch Lecture Hall , Chemistry Complex

Title :Ideality and Tunneling Level Systems (TLS) in Amorphous Silicon Films

 

Physical Chemistry Seminar Dr. Aleksandra Vojvodic ( University of Pennsylvania)

Thu, 2017-09-28 13:00 - 14:00
Speaker: 
Host: Fakhraai
Location: 
Lynch Lecture Hall Chemistry Complex

Title: Computationally predicting transition-metal compound materials for catalysis

 

Special Physical Chemistry Seminar: Victor Muñoz, University of California-Merced

Mon, 2017-05-08 16:00 - 17:00
Speaker: 

Prof. Victor Muñoz

University of California, Merced

Location: 
Lynch Lecture Hall

Using Physical Chemistry to Solve Important Problems in Molecular Biology and Nanotechnology

 

Special Physical Chemistry Seminar: Todd Kraus, University of Rochester

Tue, 2017-05-02 16:00 - 17:00
Speaker: 

Prof. Todd Kraus

University of Rochester

Location: 
Lynch Lecture Hall

Colloidal Semiconductor Nanocrystal Photocatalysts: Teaching an Old Dot New Tricks 

 

Special Physical Chemistry Seminar: Marcos Dantus, Michigan State University

Tue, 2017-04-25 16:00 - 17:00
Speaker: 

Prof. Marcos Dantus

Michigan State University

Location: 
Lynch Lecture Hall

A deep-learning approach to molecular dynamics

 

Physical Chemistry Seminar (Adam Smith, University of Akron)

Thu, 2017-03-30 13:00 - 14:00
Speaker: 

Biography Adam W. Smith was born in Texas and grew up in Utah. He was an undergraduate at the University of Utah in Salt Lake City, where he did in research on the gas phase electronic spectroscopy of diatomic metal carbides with Michael Morse. He then entered the chemistry PhD program at MIT and joined the lab of Andrei Tokmakoff. His thesis research was to investigate the structure and dynamics of proteins and peptides with femtosecond 2D IR spectroscopy. After graduating in 2008, Adam moved to UC Berkeley to do postdoctoral work with Jay T Groves. There he focused on problems in membrane biophysics and cell signaling using a wide range of advanced fluorescence microscopy methods including two-photon imaging, patterned photoactivation, single molecule imaging, photoactivated localization microscopy (PALM), and pulsed interleaved excitation fluorescence cross-correlation spectroscopy (PIE-FCCS). After his postdoc, Adam was a visiting scientist at the National University of Singapore and then briefly employed at Lawrence Berkeley National Laboratory. In 2012 he started his own lab at the University of Akron, where he is currently an Assistant Professor of Chemistry.

 

 The plasma membrane is the boundary between a cell and its surroundings. At the membrane, cells present an array of protein receptors that process environmental cues. The spatial and temporal arrangement of these receptors is critical to function, but the chemical forces driving this organization are not well understood. Membrane protein dimerization, for example, is a key regulator of many receptor pathways, but its role in others is still controversial or completely unknown. Assembly of receptor complexes upon ligand stimulation is central to many signaling pathways, but the kinetics and thermodynamics of the assembly process are still poorly understood. Lipids in the membrane have been hypothesized to play many structural and regulatory roles in receptor activation, but the details of the lipid-protein interface are still largely unexplored because of experimental difficulties. I will describe two ongoing projects in my group. In the first project we investigate membrane protein interactions in live cells using PIE-FCCS and related methods. These efforts have led to several key insights into the organization and activation mechanism of receptors like plexins, growth factor receptors, and visual photoreceptors. The second project is to resolve the details of lipid-protein coupling in model membranes to build a more complete picture of the chemical landscape that governs cell communication.

Location: 

Lynch Lecture Hall Chemistry Complex

 

inquires please contact Rosa M. Vargas rvargas@sas.upenn.edu

Physical Chemistry Seminar (Katherine A. (Kallie) Willets, Temple University)

Thu, 2017-01-26 13:00 - 14:00
Location: 

Lynch Lecture Hall Chemistry Complex

Inquires please contact Camille Pride at campride@sas.upenn.edu

Department of Chemistry

231 S. 34 Street, Philadelphia, PA 19104-6323

215.898.8317 voice | 215.573.2112 fax | web@chem.upenn.edu

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