- Intracellularly Actuated Quantum Dot-Peptide-Doxorubicin Nanobioconjugates for Controlled Drug Delivery via the Endocytic Pathway
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Nanoparticle (NP)-mediated drug delivery (NMDD) has emerged as a novel method to overcome the limitations of traditional systemic delivery of therapeutics, including the controlled release of the NP-associated drug cargo. Currently, our most advanced understanding of how to control NP-associated cargos is in the context of soft nanoparticles (e.g., liposomes), but less is known about controlling the release of cargos from the surface of hard NPs (e.g., gold NPs). Here we employ a semiconductor quantum dot (QD) as a prototypical hard NP platform and use intracellularly triggered actuation to achieve spatiotemporal control of drug release and modulation of drug efficacy. Conjugated to the QD are two peptides: (1) a cell-penetrating peptide (CPP) that facilitates uptake of the conjugate into the endocytic pathway and (2) a display peptide conjugated to doxorubicin (DOX) via three different linkages (ester, disulfide, and hydrazone) that are responsive to enzymatic cleavage, reducing conditions, and low pH, respectively. Formation of the QD-[peptide-DOX]-CPP complex is driven by self-assembly that allows control over both the ratio of each peptide species conjugated to the QD and the eventual drug dose delivered to cells. F?rster resonance energy transfer assays confirmed successful assembly of the QD-peptide complexes and functionality of the linkages. Confocal microscopy was employed to visualize residence of the QD-[peptide-DOX]-CPP complexes in the endocytic pathway, and distinct differences in DOX localization were noted for the ester linkage, which showed clear signs of nuclear delivery versus the hydrazone, disulfide, and amide control. Finally, delivery of the QD-[peptide-DOX]-CPP conjugate resulted in cytotoxicity for the ester linkage that was comparable to free DOX. Attachment of DOX via the hydrazone linkage facilitated intermediary toxicity, while the disulfide and amide control linkages showed minimal toxicity. Our data demonstrate the utility of hard NP-peptide bioconjugates to function as multifunctional scaffolds for simultaneous control over cellular drug uptake and toxicity and the vital role played by the nature of the chemical linkage that appends the drug to the NP carrier.
- Sangtani, Ajmeeta,Petryayeva, Eleonora,Wu, Miao,Susumu, Kimihiro,Oh, Eunkeu,Huston, Alan L.,Lasarte-Aragones, Guillermo,Medintz, Igor L.,Algar, W. Russ,Delehanty, James B.
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- Stereochemical requirements for β-hairpin formation: Model studies with four-residue peptides and depsipeptides
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Spectroscopic and crystallographic data are present for a series of tetrapeptides and analogous depsipeptides that can form a minimal β-hairpin (two intramolecular hydrogen bonds). These model compounds have been used to test the hypothesis that 'mirror image' β-turns promote β-hairpin formation. This hypothesis was inspired by a statistical survey of β-hairpins in globular proteins (Sibanda, B.L.; Thornton, J.M. Nature 1985, 316, 170), which showed that mirror image β-turns (type I' and type II'), although rare in general, are very commonly associated with β-hairpins containing a two-residue loop between the strand segments. Each of our four-residue molecules contains proline at the second position, to promote a central β-turn. The β-turn is induced to be either 'common' or 'mirror-image', relative to the outer residues, by choice of residue configuration (L vs D). In methylene chloride, end-capped tetrapeptide Ac-L-Val-D-Pro-D-Ala-L-Leu-NMe2 folds largely into the β-hairpin conformation, while the diastereomer Ac-L-Val-L-Pro-L-Ala-L-Leu-NMe2 displays little or no β-hairpin folding. For each diastereomer, the hydrogen-bonded driving force for β-hairpin folding is identical, and the dramatic difference in folding behavior therefore reflects a variation in the intrinsic conformational properties of the diastereomeric backbones. Similar behavior is seen for the diastereomeric peptide pair Ac-L-Val-D-Pro-Gly-L-Leu-NMe2 vs Ac-L-Val-L-Pro-Gly-L-Leu-NMe2, and for the analogous depsipeptides with a lactic acid or glycolic acid residue at the third position. Thus, our results show not only that mirror-image Pro-X turns strongly promote β-hairpin folding, but also that common β-turns strongly discourage formation of a β-hairpin with a two-residue loop.
- Haque, Tasir S.,Little, Jennifer C.,Gellman, Samuel H.
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- Enzymatic synthesis of trideuterated sialosides
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Sialic acids are a family of acidic monosaccharides often found on the termini of cell surface proteins or lipid glycoconjugates of higher animals. Herein we describe the enzymatic synthesis of the two isotopically labeled sialic acid derivatives d3-X-Gal-a-2,3-Neu5Ac and d3-X-Gal-a-2,3-Neu5Gc. Using deuterium oxide as the reaction solvent, deuterium atoms could be successfully introduced during the enzymatic epimerization and aldol addition reactions when the sialosides were generated. NMR and mass spectrometric analyses confirmed that the resulting sialosides were indeed tri-deuterated. These compounds may be of interest as internal standards in liquid chromatography/mass spectrometric assays for biochemical or clinical studies of sialic acids. This was further exemplified by the use of this tri-deuterated sialosides as internal standards for the quantification of sialic acids in meat and egg samples.
- Cai, Zhi-P.,Conway, Louis P.,Huang, Ying Y.,Wang, Wen J.,Laborda, Pedro,Wang, Ting,Lu, Ai M.,Yao, Hong L.,Huang, Kun,Flitsch, Sabine L.,Liu, Li,Voglmeir, Josef
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- NEW COMPOUNDS WITH ANTIOXIDANT AND ANTIAGING ACTIVITY
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The present invention describes new derivatives of S-allyicysteine with antioxidant and antiaging activity. Said derivatives can be used alone or in a combined formulation with other compounds with known activity.
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Page/Page column 25
(2017/06/30)
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- Design and synthesis of active heparan sulfate-based probes
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A chemoenzymatic approach for synthesizing heparan sulfate oligosaccharides with a reactive diazoacetyl saccharide residue is reported. The resultant oligosaccharides were demonstrated to serve as specific inhibitors for heparan sulfate sulfotransferases,
- Zhou, Wen,Hsieh, Po-Hung,Xu, Yongmei,O'Leary, Timothy R.,Huang, Xuefei,Liu, Jian
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supporting information
p. 11019 - 11021
(2015/07/02)
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- Hydrogen-bond-mediated folding in depsipeptide models of β-turns and α-helical turns
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The folding of several depsipeptides constructed from α-amino acids [L-proline (P) and L-alanine (A)] and α-hydroxy acids [L-lactic acid (L) and glycolic acid (G)] has been examined in methylene chloride solution by variable- temperature IR spectroscopy. Additional studies have been conducted in some cases, involving variable-temperature 1H NMR spectroscopy and molecular mechanics calculations. The depsipeptides include three-residue molecules (PLL, ALL, and PLG) that can form a 13-membered-ring amide-to-amide hydrogen bond, which, for a peptide backbone, would correspond to a single turn of an α-helix. These depsipeptides can also form 10-membered-ring amide-to-ester hydrogen bonds, which would correspond to β-trun formation for a peptide backbone. For PLL and PLG, distinct N-H stretch bands can be identified for three folding patterns: non-hydrogen-bonded, β-turn, and α-helical turn. IR-based van't Hoff analyses for PLL indicate that the α-helical turn and the β-turn are both modestly enthalpically favored relative to the non-hydrogen-bonded state, but neither turn is enthalpically preferred over the other. For PLG, in contrast, the α-helical turn appears to be enthalpically preferred over both of the alternative folding patterns. Comparison between PLL and ALL indicates that the N-terminal proline residue favors α-helical turn formation. The strengths of amide-to-amide and amide-to-ester hydrogen bonds have been compared in the context of a β-turn geometry by analyzing LG and AG in CH2Cl2. The amide-to-amide hydrogen bond is enthalpically favored by ca. 1.6 kcal/mol, but formation of this enthalpically stronger intramolecular hydrogen bond is more costly entropically. Extrapolation from the behavior of these depsipeptides leads us to predict that for tripeptides in a nonpolar environment, a β-turn will generally be enthalpically preferred over an isolated α-helical turn. β-Turn folding has previously been widely studied in model peptides and depsipeptides; however, the present report appears to represent the first experimental effort to model formation of a single α-helical turn.
- Gallo, Elizabeth A.,Gellman, Samuel H.
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p. 9774 - 9788
(2007/10/02)
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