Spiral Superstructures of Amyloid-Like Fibrils of Polyglutamic Acid: An Infrared Absorption and Vibrational Circular Dichroism Study

Fulara, Aleksandra; Lakhani, Ahmed; Wójcik, Sławomir; Nieznanska, Hanna; Keiderling, Timothy A.; Dzwolak, Wojciech

doi:10.1021/jp206271e

Cited by 58 publications

(131 citation statements)

References 27 publications

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“…Detection of β 2 -structures through infrared absorption coincides with formation of twisted supermolecular assemblies of PLGA fibrils [21]. In all our previous investigations employing high quality linear PLGA chains [20]–[21] only β 2 -aggregates were observed, although the aggregation conditions were essentially the same or very similar to those used by Fändrich and Dobson. In our earlier studies on acid-and-temperature-induced conformational transitions in PLGA, β 1 -aggregates were detected only as metastable transient forms occurring upon co–aggregation of PLGA and PDGA (poly-D-glutamic acid) [22].…”

Section: Introductionsupporting

confidence: 68%

“…While Itoh et al did not study the β 2 architecture in the context of amyloid fibrils this has become subject of recent investigations carried out by our group, as well as by Keiderling′s, Kubelka's and Bouř's groups [20]–[24]. Detection of β 2 -structures through infrared absorption coincides with formation of twisted supermolecular assemblies of PLGA fibrils [21]. In all our previous investigations employing high quality linear PLGA chains [20]–[21] only β 2 -aggregates were observed, although the aggregation conditions were essentially the same or very similar to those used by Fändrich and Dobson.…”

Section: Introductionmentioning

confidence: 81%

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Covalent Defects Restrict Supramolecular Self-Assembly of Homopolypeptides: Case Study of β2-Fibrils of Poly-L-Glutamic Acid

et al. 2014

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Poly-L-glutamic acid (PLGA) often serves as a model in studies on amyloid fibrils and conformational transitions in proteins, and as a precursor for synthetic biomaterials. Aggregation of PLGA chains and formation of amyloid-like fibrils was shown to continue on higher levels of superstructural self-assembly coinciding with the appearance of so-called β2-sheet conformation manifesting in dramatic redshift of infrared amide I′ band below 1600 cm−1. This spectral hallmark has been attributed to network of bifurcated hydrogen bonds coupling C = O and N-D (N-H) groups of the main chains to glutamate side chains. However, other authors reported that, under essentially identical conditions, PLGA forms the conventional in terms of infrared characteristics β1-sheet structure (exciton-split amide I′ band with peaks at ca. 1616 and 1683 cm−1). Here we attempt to shed light on this discrepancy by studying the effect of increasing concentration of intentionally induced defects in PLGA on the tendency to form β1/β2-type aggregates using infrared spectroscopy. We have employed carbodiimide-mediated covalent modification of Glu side chains with n-butylamine (NBA), as well as electrostatics-driven inclusion of polylysine chains, as two different ways to trigger structural defects in PLGA. Our study depicts a clear correlation between concentration of defects in PLGA and increasing tendency to depart from the β2-structure toward the one less demanding in terms of chemical uniformity of side chains: β1-structure. The varying predisposition to form β1- or β2-type aggregates assessed by infrared absorption was compared with the degree of morphological order observed in electron microscopy images. Our results are discussed in the context of latent covalent defects in homopolypeptides (especially with side chains capable of hydrogen-bonding) that could obscure their actual propensities to adopt different conformations, and limit applications in the field of synthetic biomaterials.

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Section: Introductionsupporting

confidence: 68%

Section: Introductionmentioning

confidence: 81%

Covalent Defects Restrict Supramolecular Self-Assembly of Homopolypeptides: Case Study of β2-Fibrils of Poly-L-Glutamic Acid

et al. 2014

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“…Amyloid Formation by Polyamino Acids-The preparation of polyamino acid (PAA) amyloids was reported previously (45)(46)(47). Briefly, the 1 mg of lyophilized powder of positively charged poly-L-lysine (PLL) (M r 70,000 -150,000; Sigma) and negatively charged polyglutamic acid (PE) (M r 2000 -15,000; Sigma) were separately dissolved in 1 ml of sterile Milli-Q water.…”

Section: Methodsmentioning

confidence: 99%

“…To do so, we used positively charged PLL, negatively charged PE, and neutral PLA. All of these PAAs have been previously reported to form amyloid in vitro (45)(46)(47).…”

Section: Rho Kinase Signaling Modulates Cell Contractility Onmentioning

confidence: 99%

Cell Adhesion on Amyloid Fibrils Lacking Integrin Recognition Motif

Jacob¹,

George²,

Singh

et al. 2016

Journal of Biological Chemistry

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Amyloids are highly ordered, cross-␤-sheet-rich protein/peptide aggregates associated with both human diseases and native functions. Given the well established ability of amyloids in interacting with cell membranes, we hypothesize that amyloids can serve as universal cell-adhesive substrates. Here, we show that, similar to the extracellular matrix protein collagen, amyloids of various proteins/peptides support attachment and spreading of cells via robust stimulation of integrin expression and formation of integrin-based focal adhesions. Additionally, amyloid fibrils are also capable of immobilizing non-adherent red blood cells through charge-based interactions. Together, our results indicate that both active and passive mechanisms contribute to adhesion on amyloid fibrils. The present data may delineate the functional aspect of cell adhesion on amyloids by various organisms and its involvement in human diseases. Our results also raise the exciting possibility that cell adhesivity might be a generic property of amyloids.

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“…7,8 Consequently, VCD has become an essential tool employed in biophysical, biochemical, and pharmaceutical research laboratories. [9][10][11][12][13][14][15][16] To the best of our knowledge, the only VCD spectra of chiral organic radicals have been reported by Mori et al 17 However, these radical cations were obtained on addition of a chemical oxidant, so that many aspects of the chiroptical activity (e.g., the reversibility of the oxidation, and optically transparent thin-layer electrochemical (OTTLE) 18 cell applicable for VCD measurements on electrochemically generated radical ions, using a commercially available VCD spectrometer.…”

Section: Introductionmentioning

confidence: 99%

An optically transparent thin-layer electrochemical cell for the study of vibrational circular dichroism of chiral redox-active molecules

Domingos¹,

Luyten²,

Anrooij³

et al. 2013

Review of Scientific Instruments

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An optically transparent thin-layer electrochemical cell for the study of vibrational circular dichroism of chiral redox-active molecules Domingos, S.R.; Luyten, H.; van Anrooij, F.; Sanders, H. J.; Bakker, B.H.; Buma, W.J.; Hartl, F.; Woutersen, S. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. An optically transparent thin-layer electrochemical (OTTLE) cell with a locally extended optical path has been developed in order to perform vibrational circular dichroism (VCD) spectroscopy on chiral molecules prepared in specific oxidation states by means of electrochemical reduction or oxidation. The new design of the electrochemical cell successfully addresses the technical challenges involved in achieving sufficient infrared absorption. The VCD-OTTLE cell proves to be a valuable tool for the investigation of chiral redox-active molecules.

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Spiral Superstructures of Amyloid-Like Fibrils of Polyglutamic Acid: An Infrared Absorption and Vibrational Circular Dichroism Study

Cited by 58 publications

References 27 publications

Covalent Defects Restrict Supramolecular Self-Assembly of Homopolypeptides: Case Study of β2-Fibrils of Poly-L-Glutamic Acid

Covalent Defects Restrict Supramolecular Self-Assembly of Homopolypeptides: Case Study of β2-Fibrils of Poly-L-Glutamic Acid

Cell Adhesion on Amyloid Fibrils Lacking Integrin Recognition Motif

An optically transparent thin-layer electrochemical cell for the study of vibrational circular dichroism of chiral redox-active molecules

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