SPECIAL TIME AND LOCATION - Biophysical chemistry in the membrane: visualizing protein lipid interactions and multiscale organization using infrared spectroscopic imaging.

Date: 
Thursday, January 15, 2015 - 2:00pm to Friday, January 16, 2015 - 10:00am
Speaker: 
Carlos Baiz
Speaker's Institution: 
MIT/University of Chicago

Research Interests

Biophysical chemistry in the membrane: visualizing protein lipid interactions and multiscale organization using infrared spectroscopic imaging.    

Seminars

Thursday, January 15, 2pm, 331 Klamath Hall: Research Seminar

Friday, January 16, 9am, 217 LISB: Future Research Workshop

Title and Abstract

"Mapping protein conformational ensembles and folding pathways with temperature-jump two-dimensional infrared spectroscopy"

Understanding the relationship between protein structure and dynamics remains a central topic in biophysics. Structural fluctuations, disorder, and conformational rearrangements are key elements of protein function. Measuring protein dynamics requires methods that combine structural sensitivity with fast time resolution, which remain particularly challenging.

In this seminar I will describe a recently-developed toolkit that combines ultrafast two-dimensional infrared (2D IR) spectroscopy with site-specific isotope labeling, spectral simulations based on spectroscopic maps, and Markov state models derived from extensive MD simulations. These techniques provide a detailed view of the equilibrium conformational heterogeneity and folding pathways of NTL9, a 39-residue ?/? miniprotein. Spectra of the folded ensemble suggest that certain regions exhibit significant disorder and solvent penetration into the backbone, while others remain in rigid hydrogen bonded configurations. Temperature-jump folding experiments provide evidence for a well-defined folding mechanism initiated by the formation of the rigid ?-helix followed by the collapse of the ?-sheet. 2DIR spectroscopy measures snapshots of protein conformational ensembles with subpicosecond time resolution. Amide-I vibrations, consisting of backbone C=O stretching modes, contain a wealth of structural information, and 2D IR offers superior structural sensitivity by spreading the spectral information onto two frequency axes to measure couplings between different vibrational modes. 

Select Publications

Carlos R. Baiz, Yu-Shan Lin, Chunte Sam Peng, Kyle A. Beauchamp, Vincent A. Voelz, Vijay S. Pande ,and Andrei Tokmakoff "A Molecular Interpretation of 2D IR Protein Folding Experiments with Markov State Models", Biophysical Journal, 106, 1359 (2014)

 

Carlos R. Baiz, Chunte S. Peng, Michael E. Reppert, Kevin C. Jones, and Andrei Tokmakoff, "Coherent two-dimensional infrared spectroscopy: Quantitative analysis of protein secondary structure in solution", Analyst, 137, 1793-1799 (2012)

Carlos R. Baiz and Kevin J. Kubarych, "Ultrafast Transient Vibrational Stark Spectroscopy: Exploring Excited-State Charge-Transfer by Measuring the Solvent Response", J. Amer. Chem. Soc (Comm), 132 (37), 12784-12785 (2010)