Democracy&amp;#39;s Ancient Ancestors

Fleming, Daniel Ε.

doi:10.1017/cbo9780511499623

Cited by 236 publications

(6 citation statements)

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“…Instead, the major peaks in the amide I region absorb between 1640-1650 cm −1 , indicative of disordered hydrogen bonds (shaded green in Figure 2C-D). 38 Thus, the major contribution in the formation of these spherical micelles (2-3 PK/PD) or worm-like micelles (1 PK/PD and 2-3 AK/AD) are driven by the formation of diphenylalanine hydrophobic core solubilized by the hydrophilic lysine or aspartic acid tail. 39 In contrast, 1 AK/AD show prominent characteristics of anti-parallel β-sheet arrangement of the peptide backbone which absorbs at 1620 and 1687 cm −1 for 1 AK and at 1623 and 1696 cm −1 for 1 AD (shaded blue in Figure 2C-D).…”

Section: Characterization Of the Peptide Nanostructuresmentioning

confidence: 99%

Customizing Morphology, Size, and Response Kinetics of Matrix Metalloproteinase-Responsive Nanostructures by Systematic Peptide Design

et al. 2019

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Over-expression and activation of matrix metalloproteinase-9 (MMP-9) is associated with multiple diseases, and can serve as a stimulus to activate nanomaterials for sensing and controlled release. In order to achieve autonomous therapeutics with improved space-time targeting capabilities, several features need to be considered beyond the introduction of an enzyme-cleavable linker into a nanostructure. We introduce guiding principles for a customizable platform using supramolecular peptide nanostructures with three modular components to achieve tunable kinetics and morphology changes upon MMP-9 exposure. This approach enables: (1) fine-tuning of kinetics through introduction of ordered/disordered structures, (2) a 12-fold variation in hydrolysis rates achieved by electrostatic (mis) matching of particle and enzyme charge, and (3) selection of enzymatic reaction products that are either cell-killing nanofibers or that disintegrate. These guiding principles, which can be rationalized and involve exchange of just a few amino acids, enable systematic customization of enzyme-responsive peptide nanostructures for general use in performance optimization of enzyme-responsive materials.

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Section: Characterization Of the Peptide Nanostructuresmentioning

confidence: 99%

Customizing Morphology, Size, and Response Kinetics of Matrix Metalloproteinase-Responsive Nanostructures by Systematic Peptide Design

et al. 2019

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“…Aromatic stacking and β-sheet H-bonding interactions govern the self-assembly of APAs in water, with nanostructure morphologies including spheres, cylindrical micelles, sheets, ribbons, tapes, and nanofibers. 34 When designed appropriately, APA nanostructures can entangle to form gels upon changes in ionic strength, pH, solvent, or addition of specific salts.…”

Section: Introductionmentioning

confidence: 99%

Supramolecular Tuning of H₂S Release from Aromatic Peptide Amphiphile Gels: Effect of Core Unit Substituents

et al. 2019

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H 2 S is a gasotransmitter with several physiological roles, but its reactivity and short half-life in biological media make it difficult to deliver in a controlled manner. For biological applications of the gas, hydrogels have the potential to deliver H 2 S with several advantages over other donor systems, including localized delivery, controlled release rates, biodegradation, and variable mechanical properties. In this study, we designed and evaluated peptide-based H 2 S-releasing hydrogels with controllable H 2 S delivery. The hydrogels were prepared from short, selfassembling aromatic peptide amphiphiles (APAs), functionalized on their N-terminus with Saroylthiooximes (SATOs), which release H 2 S in response to a thiol trigger. The APAs were studied both in solution and in gel forms, with gelation initiated by addition of CaCl 2. Various substituents were included on the SATO component of the APAs in order to evaluate their effect on selfassembled morphology and H 2 S release rate in both the solution and gel phases. Transmission electron microscopy (TEM) images confirmed that all H 2 S-releasing APAs self-assembled into nanofibers above a critical aggregation concentration (CAC) of ~0.5 mg/mL. Below the CAC, substituents on the SATO group affected H 2 S release rates predictably in line with electronic effects (Hammett σ values) according to a linear free energy relationship. Above the CAC, circular dichroism, infrared, and fluorescence spectroscopies demonstrated that substituents influenced the self-assembled structures by affecting hydrogen bonding (β-sheet formation) and π-π stacking. At these concentrations, electronic control over release rates diminished, both in solution and in the gel form. Rather, the release rate depended primarily on the degree of organization in the β-sheets and the amount of π-π stacking. This supramolecular control over release rate may enable the evaluation of H 2 S-releasing hydrogels with different release rates in biological applications.

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“…We also consider η-η ′ mixing and showed that due to the vanishing of the gluon contributions the flavor structure of the SCET operators imply Br( B → D ( * ) η ′ )/Br( B → D ( * ) η) = tan 2 (θ) = 0.67 where θ = 39.3 • is the η −η ′ mixing angle in the FKS scheme, and that Br( B → D ( * ) φ)/Br( B → D ( * ) ω) < ∼ 0.2. Corrections here are only order α s ( √ EΛ) and should be computed in the near future. At one-loop the effect of operator mixing will also need to be considered [33]. Finally, tests of SU(3) symmetry were given in Eqs.…”

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confidence: 99%

Heavy quark symmetry in isosinglet non-leptonic B-decays

2005

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We use a factorization theorem from the soft-collinear effective theory along with heavy quark symmetry to make model independent predictions forB 0 → D ( * )0 M where M = {η, η ′ , φ, ω}. Gluon production of these isosinglet mesons is included. We predict the equality of branching fractions in theB → DM andB → D * M channels, with corrections at order Λ QCD /Q and α s (Q) where Q = m b , m c , or E M . We also predict that Br(B 0 → Dη ′ )/Br(B 0 → Dη) = tan 2 θ = 0.67 and Br(B → Dφ)/Br(B → Dω) < ∼ 0.2, where here there are also α s ( √ EΛ) corrections. These results agree well with the available data. A test for SU(3) violation in these decays is constructed.Nonleptonic weak-decays involving b → cqq ′ transitions provide an interesting framework for testing power expansions and factorization in QCD at the m b ∼ 5 GeV scale. The Soft-Collinear Effective Theory (SCET) [1,2,3,4] has been used to make predictions for two-body non-leptonic b → c decays such as color allowed decaysB → DThese predictions make use of a systematic expansion in Λ QCD /m b,c and Λ QCD /E M . For earlier work on color allowed decays see [9,10,11,12]. The nature of factorization has also been studied in inclusive B → D ( * ) X decays, as well as decays to multi-body final states like B → Dππππ, and decays to higher spin mesons [13,14,15,16].The Belle and BaBar Collaborations have recently reported measurements of the color suppressed decay channelsB 0 → D ( * )0 η,B 0 → D 0 η ′ , andB 0 → D ( * )0 ω which have an isosinglet meson M in the final state [17,18,19]. A summary of the data is given in Table I. By now it is well understood that "naive" factorization [20] fails miserably for these "color-suppressed" decays. A rigorous framework for discussing them in QCD is provided by the factorization theorem derived in Ref. [6]. The presence of isosinglet mesons enriches the structure of the decays due to η-η ′ and ω-φ mixing effects and gluon production mechanisms [21,22,23]. In this paper, we generalize the SCET analysis of [6] to include isosinglets. We also construct a test of SU(3) flavor symmetry in color suppressed decays, using our results to include the η − η ′ mixing.The quark level weak Hamiltonian is

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Democracy's Ancient Ancestors

Cited by 236 publications

References 0 publications

Customizing Morphology, Size, and Response Kinetics of Matrix Metalloproteinase-Responsive Nanostructures by Systematic Peptide Design

Customizing Morphology, Size, and Response Kinetics of Matrix Metalloproteinase-Responsive Nanostructures by Systematic Peptide Design

Supramolecular Tuning of H₂S Release from Aromatic Peptide Amphiphile Gels: Effect of Core Unit Substituents

Heavy quark symmetry in isosinglet non-leptonic B-decays

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Democracy&#39;s Ancient Ancestors

Cited by 236 publications

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Customizing Morphology, Size, and Response Kinetics of Matrix Metalloproteinase-Responsive Nanostructures by Systematic Peptide Design

Customizing Morphology, Size, and Response Kinetics of Matrix Metalloproteinase-Responsive Nanostructures by Systematic Peptide Design

Supramolecular Tuning of H2S Release from Aromatic Peptide Amphiphile Gels: Effect of Core Unit Substituents

Heavy quark symmetry in isosinglet non-leptonic B-decays

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Product

Resources

About

Democracy's Ancient Ancestors

Supramolecular Tuning of H₂S Release from Aromatic Peptide Amphiphile Gels: Effect of Core Unit Substituents