pH-dependent helix folding dynamics of poly-glutamic acid

Gooding, Edward A.; Sharma, Shalu; Petty, Sarah A.; Fouts, Elizabeth; Palmer, Colin; Nolan, Brian E.; Völk, Martin

doi:10.1016/j.chemphys.2012.11.009

Cited by 43 publications

(52 citation statements)

References 66 publications

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“…The decrease of α-helix and increase of random coil in the γ-PGA secondary structure, as analyzed by CD, are considered to be the main conformation responsible for the shape variation at different pH values. A similar helix to random coil structural change associated with pH variation has been substantiated for poly(glutamic acid) using CD studies 30 , 31 . The conformation of the poly(glutamic acid) was reported to change from random coil to α-helix as the solution pH decreased from 7.2 to 3.0 30 .…”

Section: Discussionmentioning

confidence: 68%

Conformations and molecular interactions of poly-γ-glutamic acid as a soluble microbial product in aqueous solutions

Wang¹,

Chen

Wang

et al. 2017

Sci Rep

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Soluble microbial products (SMPs) are of significant concern in the natural environment and in engineered systems. In this work, poly-γ-glutamic acid (γ-PGA), which is predominantly produced by Bacillus sp., was investigated in terms of pH-induced conformational changes and molecular interactions in aqueous solutions; accordingly, its sedimentation coefficient distribution and viscosity were also elucidated. Experimental results indicate that pH has a significant impact on the structure and molecular interactions of γ-PGA. The conformation of the γ-PGA acid form (γ-PGA-H) is rod-like while that of the γ-PGA sodium form (γ-PGA-Na) is sphere-like. The transformation from α-helix to random coil in the γ-PGA secondary structure is primarily responsible for this shape variation. The intramolecular hydrogen bonds in the γ-PGA-H structure decrease and intramolecular electrostatic repulsion increases as pH increases; however, the sedimentation coefficient distributions of γ-PGA are dependent on intermolecular interactions rather than intramolecular interactions. Concentration has a more substantial effect on intermolecular electrostatic repulsion and chain entanglement at higher pH values. Consequently, the sedimentation coefficient distributions of γ-PGA shift significantly at pH 8.9 from 0.1 to 1.0 g/L, and the viscosity of γ-PGA (5% w/v) significantly increases as pH increases from 2.3 to 6.0.

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Section: Discussionmentioning

confidence: 68%

Conformations and molecular interactions of poly-γ-glutamic acid as a soluble microbial product in aqueous solutions

Wang¹,

Chen

Wang

et al. 2017

Sci Rep

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“…Gooding et al, 9 providing a wealth of information on the dynamics in these systems. In both cases, the monitoring of the unfolding was performed by detecting absorption changes within the amide I′ bands in the infrared (IR) spectral range.…”

Section: And Bymentioning

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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“…The most rapid process is known to be the formation of α-helices from random peptides which corresponds to the first dynamical step in folding of many proteins [12]. Studies of ultrarapid folding of simple peptides prone to form α-helices such as polyAlanine or poly(Glutamic acid) have been carried out by several groups [13][14][15][16]. Measurement of the helical fraction is usually obtained through the monitoring of the amide I band absorption in the mid-IR.…”

Section: Thermal Denaturation Of the Poly(glutamic Acid)mentioning

confidence: 99%

Time-resolved circular dichroism: What can we learn on conformational changes?

Hache

2015

SPIE Proceedings

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Time-resolved circular dichroism (CD) measurements can yield relevant information on the dynamics of conformational changes in molecules on the condition that some a priori knowledge is obtained. This can be the use of simple models such as the excitonic coupling or the octant rule or the phenomenological relationship between far-UV CD and secondary structures in proteins for example. This article describes such experiments where CD has brought relevant conformational information.

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pH-dependent helix folding dynamics of poly-glutamic acid

Cited by 43 publications

References 66 publications

Conformations and molecular interactions of poly-γ-glutamic acid as a soluble microbial product in aqueous solutions

Conformations and molecular interactions of poly-γ-glutamic acid as a soluble microbial product in aqueous solutions

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

Time-resolved circular dichroism: What can we learn on conformational changes?

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