Temperature-jump 2D IR Spectroscopy to Study Protein Conformational Dynamics

Temperature-jump 2D IR Spectroscopy to Study Protein Conformational Dynamics
Author: Kevin Chapman Jones
Publisher:
Total Pages: 324
Release: 2012
Genre:
ISBN:

Download Temperature-jump 2D IR Spectroscopy to Study Protein Conformational Dynamics Book in PDF, Epub and Kindle

Temperature-jump (T-jump) two-dimensional infrared spectroscopy (2D IR) is developed, characterized, and applied to the study of protein folding and association. In solution, protein conformational changes span a wide range of timescale from nanoseconds to minutes. Ultrafast 2D IR spectroscopy measures time-dependent structural changes within the protein ensemble by probing the frequency changes associated with amide I backbone vibrations. Combining 2D IR with a perturbing laser-induced T-jump enables the study of conformational dynamics from 5 ns to 50 ms. To access a finer time-sampling of the conformational evolution, a one-dimensional variant of 2D IR, heterodyne-detected dispersed vibrational echo spectroscopy (HDVE), is implemented. The framework for interpreting transient HDVE and 2D IR spectra is developed, and we propose a method to remove the linear absorption distortions along both frequency axes. We first present the T-jump 2D IR spectra of a dipeptide to reveal the general amide I baseline response expected in the absence of conformational change. To facilitate the analysis of T-jump data, singular value decomposition (SVD) is employed for reducing noise, identifying the number of distinguishable states, and separating spectral changes based on shared timescales. Finally, T-jump 2D IR spectroscopy is applied to study the unfolding of ubiquitin, disordering of the 12-residue p-hairpin peptide trpzip2 (TZ2), and the dissociation of insulin dimers to monomers. Experimental results for ubiquitin highlight the importance of linear absorption corrections for interpretation of the data. In response to the T-jump, 2D IR results indicate p-sheet structure melts in ubiquitin with a small amplitude (~10 gs) and large amplitude (17 ms) response. Isotope-labeling T-jump experiments on TZ2 allow for the proposal of a free energy surface in which transitions from a native and misfolded state proceed through a disordered hub-like state with a 1-2 gs timescale. Multiple timescales are observed in the T-jump induced dissociation of insulin. Based on their spectral features and concentration dependence, the insulin timescales can be assigned to dissociation, disordering, and oligomerization processes. With these applications, we demonstrate the capability of T-jump 2D IR spectroscopy to reveal detailed molecular dynamics.

Two-dimensional Infrared Spectroscopy and Computational Modeling

Two-dimensional Infrared Spectroscopy and Computational Modeling
Author: Ziad Ganim
Publisher:
Total Pages: 291
Release: 2010
Genre:
ISBN:

Download Two-dimensional Infrared Spectroscopy and Computational Modeling Book in PDF, Epub and Kindle

In this thesis, dynamics experiments are developed that can be used to study protein conformational changes such as folding and binding. Every functional motion of a protein is inextricably linked to conformational dynamics. However, most of our insight into protein folding and binding is indirectly obtained through kinetics experiments that measure reaction rates and reveal how fast populations of stable states interconvert. Two-dimensional infrared spectroscopy (2D IR) is the central tool developed in this thesis for protein dynamics experiments due to its combination of time and structural resolution. As a vibrational spectroscopy, 2D IR potentially offers femtosecond time resolution. Its advantages over linear, absorption spectroscopy come through correlating excitation and emission frequencies to allow for a separation of homogenous and inhomogeneous line shape components, and to give rise to structurally sensitive cross-peaks. One general problem was repeatedly addressed in this thesis: how can 2D IR spectra best be modeled to reveal atomistic structural information? The key feature that now sets 2D IR apart from other fast protein probes is that the data can readily be calculated from an atomistic structure or molecular dynamics simulation using the methods developed in this thesis work. Demonstrative applications are presented for the amide 1-11 spectroscopy of NMA, the amide 1'-II' spectroscopy of poly-L-lysine, isotope-edited 2D IR spectroscopy of trpzip2, and transient 2D JR spectroscopy of ubiquitin unfolding after a temperature jump. The emerging paradigm is to interpret 2D IR spectra with the aid of an atomistic, molecular dynamics simulation. The applications to protein binding use the monomer-dimer transition of insulin as a model system. Using a combination of experiments and simulations, this equilibrium was characterized as a function of protein concentration, temperature, and solvent. Finally, as a complement to the structural information provided by 2D IR, dye-labeling and intrinsic tyrosine fluorescence experiments on insulin are described.

Two-dimensional Infrared Spectroscopy as a General Approach for the Study of Protein Dynamics

Two-dimensional Infrared Spectroscopy as a General Approach for the Study of Protein Dynamics
Author: Sashary Ramos
Publisher:
Total Pages: 250
Release: 2020
Genre: Fourier transform infrared spectroscopy
ISBN:

Download Two-dimensional Infrared Spectroscopy as a General Approach for the Study of Protein Dynamics Book in PDF, Epub and Kindle

Complete understanding of protein function requires knowledge of protein conformational dynamics, or the structural fluctuations of a protein. However, characterization of protein dynamics is challenged by protein complexity, as they are large, heterogeneous molecules with potentially important motions on very fast timescales. This complexity demands the use of a technique with high spatial and temporal resolution. Two-dimensional infrared (2D IR) spectroscopy has emerged as a powerful tool for the characterization and direct measurement of molecular heterogeneity and dynamics due to its excellent spatial and temporal resolution. However, application to proteins is hindered by their severely congested spectra due to the large number of similar bonds. To overcome this issue, proteins can be site-specifically labeled with spectrally resolved IR probes that are active in the transparent frequency region (~1800 - 2500 cm-1) and are sensitive to their environment. The studies presented here take advantage of the combination of site-specific labeling and IR spectroscopy to study the environments and dynamics at specific locations in three distinct protein systems. Herein, I describe our investigations of dynamic complexes of proteins that have challenged experimental characterization with conventional methods: plastocyanin (Pc) and its binding partner cytochrome f (cyt f); cytochrome P450cam (P450cam) and substrates or its redox partner, putidaredoxin; and the SH3Sho1 domain and the proline-rich (PR) recognition motif of its binding partner Pbs2. In addition, we describe my attempts at improving the experimental technique of site-specific IR spectroscopy as a general biophysical approach for protein characterization. Overall, I present evidence for the importance of fast dynamics in protein function and illustrate the rich information provided by 2D IR spectroscopy to complement existing biophysical methods.

Ultrafast Infrared Vibrational Spectroscopy

Ultrafast Infrared Vibrational Spectroscopy
Author: Michael D. Fayer
Publisher: CRC Press
Total Pages: 491
Release: 2013-03-04
Genre: Science
ISBN: 1466510137

Download Ultrafast Infrared Vibrational Spectroscopy Book in PDF, Epub and Kindle

The advent of laser-based sources of ultrafast infrared pulses has extended the study of very fast molecular dynamics to the observation of processes manifested through their effects on the vibrations of molecules. In addition, non-linear infrared spectroscopic techniques make it possible to examine intra- and intermolecular interactions and how such interactions evolve on very fast time scales, but also in some instances on very slow time scales. Ultrafast Infrared Vibrational Spectroscopy is an advanced overview of the field of ultrafast infrared vibrational spectroscopy based on the scientific research of the leading figures in the field. The book discusses experimental and theoretical topics reflecting the latest accomplishments and understanding of ultrafast infrared vibrational spectroscopy. Each chapter provides background, details of methods, and explication of a topic of current research interest. Experimental and theoretical studies cover topics as diverse as the dynamics of water and the dynamics and structure of biological molecules. Methods covered include vibrational echo chemical exchange spectroscopy, IR-Raman spectroscopy, time resolved sum frequency generation, and 2D IR spectroscopy. Edited by a recognized leader in the field and with contributions from top researchers, including experimentalists and theoreticians, this book presents the latest research methods and results. It will serve as an excellent resource for those new to the field, experts in the field, and individuals who want to gain an understanding of particular methods and research topics.

Protein Folding and Misfolding

Protein Folding and Misfolding
Author: Heinz Fabian
Publisher: Springer Science & Business Media
Total Pages: 257
Release: 2011-09-18
Genre: Science
ISBN: 3642222307

Download Protein Folding and Misfolding Book in PDF, Epub and Kindle

Infrared spectroscopy is a new and innovative technology to study protein folding/misfolding events in the broad arsenal of techniques conventionally used in this field. The progress in understanding protein folding and misfolding is primarily due to the development of biophysical methods which permit to probe conformational changes with high kinetic and structural resolution. The most commonly used approaches rely on rapid mixing methods to initiate the folding event via a sudden change in solvent conditions. Traditionally, techniques such as fluorescence, circular dichroism or visible absorption are applied to probe the process. In contrast to these techniques, infrared spectroscopy came into play only very recently, and the progress made in this field up to date which now permits to probe folding events over the time scale from picoseconds to minutes has not yet been discussed in a book. The aim of this book is to provide an overview of the developments as seen by some of the main contributors to the field. The chapters are not intended to give exhaustive reviews of the literature but, instead to illustrate examples demonstrating the sort of information, which infrared techniques can provide and how this information can be extracted from the experimental data. By discussing the strengths and limitations of the infrared approaches for the investigation of folding and misfolding mechanisms this book helps the reader to evaluate whether a particular system is appropriate for studies by infrared spectroscopy and which specific advantages the techniques offer to solve specific problems.

Thermal Unfolding Dynamics of Proteins Probed by Nonlinear Infrared Spectroscopy

Thermal Unfolding Dynamics of Proteins Probed by Nonlinear Infrared Spectroscopy
Author: Hoi Sung Chung
Publisher:
Total Pages: 231
Release: 2007
Genre:
ISBN:

Download Thermal Unfolding Dynamics of Proteins Probed by Nonlinear Infrared Spectroscopy Book in PDF, Epub and Kindle

This thesis presents spectroscopic approaches to study the thermal unfolding dynamics of proteins. The spectroscopic tool is nonlinear infrared (IR) spectroscopy of the protein amide I band. Among various nonlinear IR techniques, two-dimensional infrared (2D IR) spectroscopy, which is an IR analogue of 2D NMR, is the most informative. A 2D IR spectrum is obtained from a double Fourier transform of the heterodyned third-order nonlinear signal, which is generated by three consecutive interactions between femtosecond IR pulses and the vibrations of the system. This technique is sensitive to the presence of P-sheet structure in proteins through the formation of cross peaks between the two characteristic vibrational modes of 0-sheets. In this work, 2D IR spectroscopy is used to measure equilibrium thermal unfolding of ribonuclease A and ubiquitin. For transient unfolding studies, the temperature of the solution is rapidly raised by a nanosecond temperature jump (T-jump) laser, which is followed by probing structural changes of proteins with dispersed vibrational echo (DVE) spectroscopy or 2D IR spectroscopy.

Protein Dynamics by Two-dimensional Infrared Spectroscopy

Protein Dynamics by Two-dimensional Infrared Spectroscopy
Author: Goran Tumbic
Publisher:
Total Pages: 0
Release: 2021
Genre: Proteins
ISBN:

Download Protein Dynamics by Two-dimensional Infrared Spectroscopy Book in PDF, Epub and Kindle

Proteins function as ensembles of interconverting structures. The motions span from picosecond bond rotations to millisecond and longer subunit displacements. Characterization of functional dynamics on all spatial and temporal scales remains challenging experimentally. Two-dimensional IR spectroscopy (2D IR) is maturing as a powerful approach for investigating proteins and their dynamics. This document outlines the advantages of IR spectroscopy, describes 2D IR and the information it provides, and introduces vibrational groups for protein analysis. Following this introduction, example studies are presented that illustrate the power and versatility of 2D IR for characterizing protein dynamics. The thesis concludes with a brief discussion of the outlook for biomolecular 2D IR.

Protein Structure, Stability, and Folding

Protein Structure, Stability, and Folding
Author: Kenneth P. Murphy
Publisher: Springer Science & Business Media
Total Pages: 258
Release: 2008-02-04
Genre: Science
ISBN: 1592591930

Download Protein Structure, Stability, and Folding Book in PDF, Epub and Kindle

In Protein Structure, Stability, and Folding, Kenneth P. Murphy and a panel of internationally recognized investigators describe some of the newest experimental and theoretical methods for investigating these critical events and processes. Among the techniques discussed are the many methods for calculating many of protein stability and dynamics from knowledge of the structure, and for performing molecular dynamics simulations of protein unfolding. New experimental approaches presented include the use of co-solvents, novel applications of hydrogen exchange techniques, temperature-jump methods for looking at folding events, and new strategies for mutagenesis experiments. Unique in its powerful combination of theory and practice, Protein Structure, Stability, and Folding offers protein and biophysical chemists the means to gain a more comprehensive understanding of some of this complex area by detailing many of the major techniques in use today.