Circular dichroism studies of distorted α-helices, twisted β-sheets, and β-turns

Manning, Mark C.; Illangasekare, Mali; Woody, Robert W.

doi:10.1016/0301-4622(88)80011-5

Cited by 280 publications

(212 citation statements)

References 68 publications

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“…1 (ref. 15,25,26). This is consistent with the electron microscopy image detailing the very long and bundled features of the assembled material, see Supplementary Fig.…”

Section: Resultssupporting

confidence: 88%

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Photoinitiated charge separation in a hybrid titanium dioxide metalloporphyrin peptide material

et al. 2014

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In natural systems, electron flow is mediated by proteins that spatially organize donor and acceptor molecules with great precision. Achieving this guided, directional flow of information is a desirable feature in photovoltaic media. Here, we design self-assembled peptide materials that organize multiple electronic components capable of performing photoinduced charge separation. Two peptides, c16-AHL 3 K 3 -CO 2 H and c16-AHL 3 K 9 -CO 2 H, self-assemble into fibres and provide a scaffold capable of binding a metalloporphyrin via histidine axial ligation and mineralize titanium dioxide (TiO 2 ) on the lysine-rich surface of the resulting fibrous structures. Electron paramagnetic resonance studies of this self-assembled material under continuous light excitation demonstrate charge separation induced by excitation of the metalloporphyrin and mediated by the peptide assembly structure. This approach to dye-sensitized semiconducting materials offers a means to spatially control the dye molecule with respect to the semiconducting material through careful, strategic peptide design.

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“…1 (ref. 15,25,26). This is consistent with the electron microscopy image detailing the very long and bundled features of the assembled material, see Supplementary Fig.…”

Section: Resultssupporting

confidence: 88%

“…When c16-AHL 3 K 9 -CO 2 H in 100 mM ammonium hydroxide is heated to 65°C and then cooled back to room temperature (RT), CD yields a spectrum slightly red shifted from a typical b-sheet spectrum, l min ¼ 224 nm, see Supplementary Fig. 1 (refs 25,26). Electron microscopy shows nanoscale bundled fibres, see Supplementary Fig.…”

Section: Resultsmentioning

confidence: 98%

Photoinitiated charge separation in a hybrid titanium dioxide metalloporphyrin peptide material

et al. 2014

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“…Such uncharacteristic spectra from the deconvolution may be the cause of distortions of the other components, such as the spectrum correlated with the unordered conformation, with the blue-shifted T -K * transitions and two maxima at 208 and 225 nm. Furthermore, two other component spectra, although correlated with the 0 turn and the @ sheet, respectively, are also ambiguous in that the bands corresponding to the T-T* transitions are shifted (Nemethy et al, 1967;Manning et al, 1988). Therefore, the overall effect of the deconvolution into six components is that of overestimating the number of the components.…”

Section: Deconvolution Of the Membrane Protein CD Spectra By The Convmentioning

confidence: 99%

Differentiation between transmembrane helices and peripheral helices by the deconvolution of circular dichroism spectra of membrane proteins

1992

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The interpretation of the circular dichroism (CD) spectra of proteins to date requires additional secondary structural information of the proteins to be analyzed, such as X-ray or NMR data. Therefore, these methods are inappropriate for a CD database whose secondary structures are unknown, as in the case of the membrane proteins. The convex constraint analysis algorithm (Perczel, A., Hollosi, M., Tusnady, G., & Fasman, G.D., 1991, Protein Eng. 4, 669-679), on the other hand, operates only on a collection of spectral data to extract the common spectral components with their spectral weights. The linear combinations of these derived "pure" CD curves can reconstruct the original data set with great accuracy. For a membrane protein data set, the five-component spectra so obtained from the deconvolution consisted of two different types of a helices (the a helix in the soluble domain and the aT helix, for the transmembrane a helix), a /3-pleated sheet, a class C-like spectrum related to /3 turns, and a spectrum correlated with the unordered conformation. The deconvoluted CD spectrum for the aT helix was characterized by a positive red-shifted band in the range 195-200 nm (+95,000 deg cm2 dmol"), with the intensity of the negative band at 208 nm being slightly less negative than that of the 222-nm band (-50,000and -60,000 deg cm2 dmol-I , respectively) in comparison with the regular (Y helix, with a positive band at 190 nm and two negative bands at 208 and 222 nm with magnitudes of +70,000, -30,000, and -30,000 deg cm2 dmol", respectively.Keywords: circular dichroism spectra; membrane proteins; secondary structure; transmembrane helices Conformational studies of membrane proteins lag far behind those of soluble proteins mainly due to the difficulties associated with crystallization of membrane proteins for X-ray diffraction studies and to the restricted movement of the proteins embedded in the membrane for

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“…However, at 2 wt % the D2I3 sequence was significantly stiffer and had the greatest red‐shift in the CD spectra at this concentration (Figure 3 A,B). Previous studies have suggested that a red‐shift in the CD spectra of β‐sheets is representative of more twisted and distorted arrangements 28, 36, 37. The degree of twisting of β‐sheets is centered around the middle of the sequence 34.…”

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confidence: 96%

Tunable Pentapeptide Self‐Assembled β‐Sheet Hydrogels

2018

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Oligopeptide‐based supramolecular hydrogels hold promise in a range of applications. The gelation of these systems is hard to control, with minor alterations in the peptide sequence significantly influencing the self‐assembly process. We explored three pentapeptide sequences with different charge distributions and discovered that they formed robust, pH‐responsive hydrogels. By altering the concentration and charge distribution of the peptide sequence, the stiffness of the hydrogels could be tuned across two orders of magnitude (2–200 kPa). Also, through reassembly of the β‐sheet interactions the hydrogels could self‐heal and they demonstrated shear‐thin behavior. Using spectroscopic and cryo‐imaging techniques, we investigated the relationship between peptide sequence and molecular structure, and how these influence the mechanical properties of the hydrogel. These pentapeptide hydrogels with tunable morphology and mechanical properties have promise in tissue engineering, injectable delivery vectors, and 3D printing applications.

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Circular dichroism studies of distorted α-helices, twisted β-sheets, and β-turns

Cited by 280 publications

References 68 publications

Photoinitiated charge separation in a hybrid titanium dioxide metalloporphyrin peptide material

Photoinitiated charge separation in a hybrid titanium dioxide metalloporphyrin peptide material

Differentiation between transmembrane helices and peripheral helices by the deconvolution of circular dichroism spectra of membrane proteins

Tunable Pentapeptide Self‐Assembled β‐Sheet Hydrogels

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