Polymeric peptide pigments with sequence-encoded properties

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Science  09 Jun 2017:
Vol. 356, Issue 6342, pp. 1064-1068
DOI: 10.1126/science.aal5005
  • Fig. 1 Sequence-dependent polymeric peptide pigments.

    (A) Schematic representation of the selected tripeptide sequences and the controlled formation of polymeric peptide pigments by enzymatic oxidation and further polymerization of preorganized tripeptides. (B) Macroscopic images of the materials formed by the self-assembly of the tripeptides (20 mM in phosphate buffer at pH 8), before (top) and after (bottom) 24 hours of enzymatic oxidation (0.2 μg/μl), including oxidation of tyrosine as a control.

  • Fig. 2 Differential organization in tripeptide assemblies.

    (A) TEM micrographs of structures formed by self-assembly of tripeptides. Scale bars, 100 nm. (B and C) DYF (B) and YFD (C) crystal structures, showing different interfaces forming the lattice. (D) FTIR absorption spectra of the tripeptides (20 mM in D2O phosphate buffer at pH 8). a.u., arbitrary units. (E) Distribution of the CZ(Y)-CA(Y)-CA(F)-CZ(F) dihedral angle for each peptide over the course of 50 ns. (F) Preferred conformations for each peptide.

  • Fig. 3 From order to disorder in polymeric peptide pigments.

    (A and B) WAXS analysis including 1D (A) and 2D (B) patterns of tripeptides before [black in (A)] or after [red in (A)] 24 hours of enzymatic oxidation. θ, angle. (C) FTIR absorption spectra of tripeptides before (solid lines) or after (dashed lines) 24 hours of enzymatic oxidation. (D) LC-MS chromatograms at 280 nm (black) and 350 nm (red) of the soluble fraction of tripeptides oxidized for 24 hours. Numbers refer to (F). (E) Summed mass/charge (m/z) intensities of soluble higher-molecular-weight polymers composed of heterogeneously connected monomers [“4” in (F)] eluted between 8 and 10 min. (F) Chemical structures of the nonoxidized peptides (“1”) and the oxidation products 3,4-dihydroxyphenylalanine (“2”) and 3,4-quinone (“3”) in the context of tripeptides. “4,” connectivity of potential aryl cross-linked and Michael addition products (supplementary materials).

  • Fig. 4 Morphology, UV-Vis absorption, and electrochemical properties of polymeric peptide pigments.

    (A) Structures formed by the polymeric peptide pigments at the micron scale, observed using optical microscopy. Scale bars for FYDox, YFDox, and DFYox, 20 μm; for DYFox, 10 μm. (B) UV-Vis absorption spectra of solution fractions of polymeric peptide pigments and oxidized tyrosine. (C) Macroscopic image of polymeric peptide pigment electrode and schematic illustration of the electrochemical cell used for discharge measurements. (D) Electrochemical potential profiles and (E) average specific capacity of polymeric peptide pigments. Error bars, standard errors (n = 3). MSE, mercury/mercurous sulfate electrode; Ah, ampere hour.

Supplementary Materials

  • Polymeric peptide pigments with sequence-encoded properties

    Ayala Lampel, Scott A. McPhee, Hang-Ah Park, Gary G. Scott, Sunita Humagain, Doeke R. Hekstra, Barney Yoo, Pim W. J. M. Frederix, Tai-De Li, Rinat R. Abzalimov, Steven G. Greenbaum, Tell Tuttle, Chunhua Hu, Christopher J. Bettinger, Rein V. Ulijn

    Materials/Methods, Supplementary Text, Tables, Figures, and/or References

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    •  Materials and Methods
    • Figs. S1 to S20
    • Tables S1 to S4
    • Captions for Movies S1 and S2
    • References

    Images, Video, and Other Media

    Movie S1
    DYF macroscopic crystallization and gelation. The movie is X8 faster than real time.
    Movie S2
    DYF crystallization and crystal elongation at the micron-scale. The movie is X8 faster than real time

    Additional Data

    Data S1

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