Nanosecond T-Jump Experiment in Poly(glutamic acid): A Circular Dichroism Study

Mendonça, Lucille; Hache, F.

doi:10.3390/ijms13022239

Cited by 16 publications

(22 citation statements)

References 20 publications

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“…The fitted timescale was found matching literature values reported in a T jump experiment in which folding was observed with the CD signal [6].…”

Section: -P2supporting

confidence: 84%

“…In fact, laser induced temperature jumps are an established method to observe the unfolding of proteins caused by the temperature increase [2,6]. In this project, the effort is directed to explore the experimental potential of pH jumps.…”

mentioning

confidence: 99%

“…confront the observed folding kinetics with the rich literature knowledge about poly-L-glutamic acid helix formation [1,2,6]. …”

mentioning

confidence: 99%

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pH jump induced α-helix folding.

Donten

Hamm

2013

EPJ Web of Conferences

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Abstract. pH can be used to impact the folding equilibrium of peptides and proteins. This fact is utilized, similarly to temperature jumps, in pH jump experiments employing laser time-resolved spectroscopy to study the function and structural dynamics of these molecules. Here the application of pH jumps in folding experiments was investigated. Experiments with poly-L-glutamic acid alpha-helix formation shown the critical aspects of pH jump experiments and yielded direct information about the folding kinetics monitored with the amide I IR band.Time-resolved studies of protein folding and functionality are an essential to understand the biological role of those macro molecules and the physical interactions responsible for their complex structure and activity. Taking advantage of time-resolved IR laser spectroscopy in the amide I range allows collection of non-equilibrium kinetic data on phenomena like protein folding [1,2]. For recording transient spectra of the rearranging molecule effective methods of initiating the process are needed. The discussed case of peptide and protein folding equilibrium, like all other thermodynamic equilibria, is temperature dependent. Additionally it is influenced, even more directly, by the properties of the biomolecule such as local charge and hydrophobic/hydrophilic interactions [1,3]. These, even for a given compound, can often be altered and controlled by pH. This is possible since one third of the 21 naturally occurring amino acids carry protonatable carboxyl or amine groups in their side chains. Side chain protonation affects the amino acid's properties by changing its charge, solvation and, in general, ability to interact with nearby molecules. As a result, side chain protonation has a dramatic impact on the protein or peptide secondary and tertiary structure. Among many examples of how protonation impacts structure and functionality, the influenza A M2 membrane proton channel [4] and folding of GCN4 leucine zippers [5] can be mentioned.When dynamic control over temperature or pH is obtained they can be used as folding triggers. In fact, laser induced temperature jumps are an established method to observe the unfolding of proteins caused by the temperature increase [2,6]. In this project, the effort is directed to explore the experimental potential of pH jumps. It is expected that this method opens access to, new more direct and truly biomimetic folding experiments. Ultimately the folding equilibrium can be switched completely, starting from completely unfolded samples.Here, formation of an α-helix was studied in pH jump experiments on poly-L-glutamic acid (poly-L-glu). The experiments had a two-fold aim. On one hand, they were conducted on a relatively simple system to explore the challenges of pH jump triggering. On the other hand, their goal was to EPJ Web of Conferences

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“…The fitted timescale was found matching literature values reported in a T jump experiment in which folding was observed with the CD signal [6].…”

Section: -P2supporting

confidence: 84%

mentioning

confidence: 99%

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pH jump induced α-helix folding.

Donten

Hamm

2013

EPJ Web of Conferences

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“…12 To achieve this rapid heating, we start from a nanosecond 20 Hz Nd:YAG laser, which pumps an optical parametric oscillator (OPO). We tune the output of the OPO to either 1.5 μm (corresponding to the ν 2 + ν 3 overtone in light water) or 1.9 μm (corresponding to the ν 2 + ν 3 overtone in heavy water).…”

Section: Experimental Setup Of the T-jump Experimentsmentioning

confidence: 99%

Comparative Study of the Folding/Unfolding Dynamics of Poly(glutamic acid) in Light and Heavy Water

et al. 2014

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The folding/unfolding equilibrium is investigated in poly(glutamic acid) (PGA) by two complementary sets of experiments: temperature-dependent steady-state circular dichroism spectra on the one hand and time-resolved circular dichroism measurements coupled with a T-jump experiment on the other hand. The experiments are performed for PGA dissolved in water for various pH values, as well as in heavy water. The kinetic and thermodynamic parameters extracted from these measurements are shown to be markedly different between light and heavy water, which is assigned to the difference in hydrogen bond energies in both solvents.

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“…To achieve time‐resolved chirality measurements different experimental set‐ups have been implemented. To investigate protein folding: stopped flow CD achieves milliseconds time‐resolution ; microsecond time‐resolution has been employed to study cytochrome c , in which photoinduced electron transfer triggers protein folding ; this time‐resolution is reduced to the ns‐regime by using a nanosecond temperature‐jump to initiate unfolding . Whereas stopped flow CD and ns temperature‐jump are experimentally limited in their time resolution, processes like photolysis and photoinduced ring opening are limited only by the laser pulses used and the photoinduced artefacts.…”

Section: Introductionmentioning

confidence: 99%

Recent advances in ultrafast time-resolved chirality measurements: perspective and outlook

Meyer-Ilse

Akimov

Dietzek

2013

Laser & Photonics Reviews

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Observing chirality changes as they occur is an important topic of research. It provides information that deepens the understanding of biomolecular configuration and conformation under environmental changes. Also, knowing the specific steps in chiral synthesis would simplify the production of specific chiral enantiomers that have a specific function. To gain better insight to the initial steps of conformational and configurational changes, the time‐resolution of chiral spectroscopy is continually pushed toward a shorter time‐scale. Recent advances have produced measurements of chirality changes with a femtosecond time‐resolution. These measurements are hindered by the inherently weak chirality signal, which can be overshadowed by different optical artefacts. This minireview will look at the so far successful techniques which measure chirality changes with femtosecond time‐resolution and discuss the advantages and disadvantages of these techniques. A short outlook will also look at new techniques that could improve the ability to measure chirality changes on an ultrafast time‐scale.

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Nanosecond T-Jump Experiment in Poly(glutamic acid): A Circular Dichroism Study

Cited by 16 publications

References 20 publications

pH jump induced α-helix folding.

pH jump induced α-helix folding.

Comparative Study of the Folding/Unfolding Dynamics of Poly(glutamic acid) in Light and Heavy Water

Recent advances in ultrafast time-resolved chirality measurements: perspective and outlook

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