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111.
Yang J Alemany LB Driver J Hartgerink JD Barron AR 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(9):2530-2545
A series of [60]fullerene-substituted phenylalanine (Baa) and lysine derivatives have been prepared by the condensation of 1,2-(4'-oxocyclohexano)fullerene with the appropriately protected (4-amino)phenylalanine and lysine, respectively. Conversion of the imine to the corresponding amine is achieved by di-acid catalyzed hydroboration. The reduction of the imine is not accompanied by hydroboration of the fullerene cage. The [70]fullerene phenylalanine derivative has also been prepared as have the di-amino acid derivatives. The compounds were characterized by MALDI-TOF mass spectrometry, UV/Vis spectroscopy, and cyclic voltammetry. 1H and 13C NMR spectroscopy allowed the observation of diastereomers. Fullerene-substituted peptides may be synthesized on relatively large scale by solid-phase peptide synthesis. The presence of the C60-substituted amino acid in a peptide has a significant effect on the secondary structures and self-assembly properties of peptides as compared to the native peptide. The antioxidant assay of Baa and a Baa-derived anionic peptide was determined to be significantly more potent than Trolox. 相似文献
112.
Victoria E. Campbell Xavier de Hatten Dr. Nicolas Delsuc Dr. Brice Kauffmann Dr. Ivan Huc Dr. Jonathan R. Nitschke Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(25):6138-6142
Systemic change : A system of transformations between helical structures was observed to be governed by interactions mediated by the electronic effects of substituents, entropic effects, the conformational preferences of organic building blocks, and the coordinative preferences of the metal ion. All of these effects were important, but all must be considered together to allow the prediction of the product observed (see scheme).
113.
Wang Y Urban C Rodríguez-Fernández J Gallego JM Otero R Martín N Miranda R Alcamí M Martín F 《The journal of physical chemistry. A》2011,115(45):13080-13087
Formation of self-assembled chains of tetrathiafulvalene (TTF) on the Cu(100) surface has been investigated by scanning tunneling microscopy and density functional theory calculations that include semiempirical van der Waals (vdW) interaction corrections. The calculations show that the chain structures observed in the experiments can only be explained by including the vdW interactions. The molecules are tilted along the chain in order to achieve maximal intermolecular interaction. The chains are metastable on the surface, which is consistent with the experimental observation that they disappear after annealing. The fact that all TTF chains observed in the experiment are short might be possibly explained by the interplay between the stabilizing vdW molecule-molecule interaction and the destabilizing rearrangement of surface atoms due to the strong molecule-substrate interaction. 相似文献
114.
A highly diastereo- and enantioselective Pd(II)-catalyzed hydrophosphination of dienones with Ph(2)PH involving formation of double C*-P bonds has been developed, providing a series of chiral tertiary diphosphines (chiral PCP pincer ligands) in high yields. A catalytic cycle for the reaction was proposed. 相似文献
115.
Adam M. Hawkridge Rebecca B. Wysocky James N. Petitte Kenneth E. Anderson Paul E. Mozdziak Oscar J. Fletcher Jonathan M. Horowitz David C. Muddiman 《Analytical and bioanalytical chemistry》2010,398(2):737-749
The domestic chicken (Gallus domesticus) has emerged as a powerful experimental model for studying the onset and progression of spontaneous epithelial ovarian cancer
(EOC) with a disease prevalence that can exceed 35% between 2 and 7 years of age. An experimental strategy for biomarker discovery
is reported herein that combines the chicken model of EOC, longitudinal plasma sample collection with matched tissues, advanced
mass spectrometry-based proteomics, and concepts derived from the index of individuality (Harris, Clin Chem 20: 1535–1542,
1974). Blood was drawn from 148 age-matched chickens starting at 2.5 years of age every 3 months for 1 year. At the conclusion
of the 1 year sample collection period, the 73 birds that remained alive were euthanized, necropsied, and tissues were collected.
Pathological assessment of resected tissues from these 73 birds confirmed that five birds (6.8%) developed EOC. A proteomics
workflow including in-gel digestion, nanoLC coupled to high-performance mass spectrometry, and label-free (spectral counting)
quantification was used to measure the biological intra-individual variability (CVW) of the chicken plasma proteome. Longitudinal plasma sample sets from two birds within the 73-bird biorepository were selected
for this study; one bird was considered “healthy” and the second bird developed late-stage EOC. A total of 116 proteins from
un-depleted plasma were identified with 80 proteins shared among all sample sets. Analytical variability (CVA) of the label-free proteomics workflow was measured using a single plasma sample analyzed five times and was found to be
≥CVW in both birds for 16 proteins (20%) and in either bird for 25 proteins (31%). Ovomacroglobulin (ovostatin) was found to increase
(p < 0.001) over a 6 month period in the late-stage EOC bird providing an initial candidate protein for further investigation. 相似文献
116.
Emily B. Corcoran Jonathan P. McMullen Franois Lvesque Michael K. Wismer John R. Naber 《Angewandte Chemie (International ed. in English)》2020,59(29):11964-11968
With the development of new photocatalytic methods over recent decades, the translation of these chemical reactions to industrial‐production scales using continuous‐flow reactors has become a topic of increasing interest. In this context, we describe our studies toward elucidating an empirically derived parameter for scaling photocatalytic reactions in flow. By evaluating the performance of a photocatalytic C?N cross‐coupling reaction across multiple reactor sizes and geometries, it was demonstrated that expressing product yield as a function of the absorbed photon equivalents provides a predictive, empirical scaling parameter. Through the use of this scaling factor and characterization of the photonic flux within each reactor, the cross‐coupling was scaled successfully from the milligram scale in batch to a multi‐kilogram reaction in flow. 相似文献
117.
Dr. Jonathan Rittle Prof. Jonas C. Peters 《Angewandte Chemie (International ed. in English)》2016,55(40):12262-12265
Nitrogenase enzymes mediate the six‐electron reductive cleavage of cyanide to CH4 and NH3. Herein we demonstrate for the first time the liberation of CH4 and NH3 from a well‐defined iron cyanide coordination complex, [SiPiPr3]Fe(CN) (where [SiPiPr3] represents a tris(phosphine)silyl ligand), on exposure to proton and electron equivalents. [SiPiPr3]Fe(CN) additionally serves as a useful entry point to rare examples of terminally‐bound Fe(CNH) and Fe(CNH2) species that, in accord with preliminary mechanistic studies, are plausible intermediates of the cyanide reductive protonation to generate CH4 and NH3. Comparative studies with a related [SiPiPr3]Fe(CNMe2) complex suggests the possibility of multiple, competing mechanisms for cyanide activation and reduction. 相似文献
118.
Diah Anggraini Wulandari Elizabeth Sidhartha Iriani Setyaningsih Jonathan Marshall Marbun Din Syafruddin 《Natural product research》2018,32(17):2067-2070
The rapid emergence of antimalarial drug resistance necessitates a continual effort on novel drug discovery. A cyanobacterium, Spirulina platensis, is a potential antimalarial agent that has been widely consumed as food supplement in the form of crude extract. It is known to possess antiviral, antibacterial and antifungi activities. This study examined the antimalarial activities of several Spirulina formulas against Plasmodium falciparum 3D7, in vitro. The tested Spirulina formulas included commercially available capsule, crude extract and alkaloid fraction. Results showed that all tested formula possessed antimalarial activities with the Spirulina capsule exhibited the highest activities (IC50 = 2.16 μg/mL). Light and electron microscopies revealed interference of the Spirulina with the parasite hemozoin formation. In conclusion, all tested Spirulina formulas and fraction exhibited moderate to high antimalarial activities. 相似文献
119.
Intercalation of trioxatriangulenium ion in DNA: binding,electron transfer,x-ray crystallography,and electronic structure 总被引:1,自引:0,他引:1
Reynisson J Schuster GB Howerton SB Williams LD Barnett RN Cleveland CL Landman U Harrit N Chaires JB 《Journal of the American Chemical Society》2003,125(8):2072-2083
Trioxatriangulenium ion (TOTA(+)) is a flat, somewhat hydrophobic compound that has a low-energy unoccupied molecular orbital. It binds to duplex DNA by intercalation with a preference for G-C base pairs. Irradiation of intercalated TOTA(+) causes charge (radical cation) injection that results in strand cleavage (after piperidine treatment) primarily at GG steps. The X-ray crystal structure of TOTA(+) intercalated in the hexameric duplex d[CGATCG](2) described here reveals that intercalation of TOTA(+) results in an unusually large extension of the helical rise of the DNA and that the orientation of TOTA(+) is sensitive to hydrogen-bonding interactions with backbone atoms of the DNA. Electronic structure calculations reveal no meaningful charge transfer from DNA to TOTA(+) because the lowest unoccupied molecular orbital of TOTA(+), (LUMO)(T), falls in the gap between the highest occupied molecular orbital, (HOMO)(D), and the (LUMO)(D) of the DNA bases. These calculations reveal the importance of backbone, water, and counterion interactions, which shift the energy levels of the bases and the intercalated TOTA(+) orbitals significantly. The calculations also show that the inserted TOTA(+) strongly polarizes the intercalation cavity where a sheet of excess electron density surrounds the TOTA(+). 相似文献
120.
In an effort to understand the formation of marine bioadhesives, mussel protein extracts were cured with various reagents and the enhanced cross-linking ability of Fe3+ was found. 相似文献