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71.
Lucia De Rosa Rossella Di Stasi Alessandra Romanelli Luca Domenico DAndrea 《Molecules (Basel, Switzerland)》2021,26(12)
Although a plethora of chemistries have been developed to selectively decorate protein molecules, novel strategies continue to be reported with the final aim of improving selectivity and mildness of the reaction conditions, preserve protein integrity, and fulfill all the increasing requirements of the modern applications of protein conjugates. The targeting of the protein N-terminal alpha-amine group appears a convenient solution to the issue, emerging as a useful and unique reactive site universally present in each protein molecule. Herein, we provide an updated overview of the methodologies developed until today to afford the selective modification of proteins through the targeting of the N-terminal alpha-amine. Chemical and enzymatic strategies enabling the selective labeling of the protein N-terminal alpha-amine group are described. 相似文献
72.
Dr. Agnese Marcelli Dr. Barbara Patrizi Prof. Alessandra Bonamore Prof. Alberto Boffi Prof. Maurizio Becucci Prof. Paolo Foggi 《Chemphyschem》2021,22(11):1134-1140
Flavohemoglobins have the particular capability of binding unsaturated and cyclopropanated fatty acids as free acids or phospholipids. Fatty acid binding to the ferric heme results in a weak but direct bonding interaction. Ferrous and ferric protein, in presence or absence of a bound lipid molecule, have been characterized by transient absorption spectroscopy. Measurements have been also carried out both on the ferrous deoxygenated and on the CO bound protein to investigate possible long-range interaction between the lipid acyl chain moiety and the ferrous heme. After excitation of the deoxygenated derivatives the relaxation process reveals a slow dynamics (350 ps) in lipid-bound protein but is not observed in the lipid-free protein. The latter feature and the presence of an extra contribution in the absorption spectrum, indicates that the interaction of iron heme with the acyl chain moiety occurs only in the excited electronic state and not in the ground electronic state. Data analysis highlights the formation of a charge-transfer complex in which the iron ion of the lipid-bound protein in the expanded electronic excited state, possibly represented by a high spin Fe III intermediate, is able to bind to the sixth coordination ligand placed at a distance of at 3.5 Å from the iron. A very small nanosecond geminate rebinding is observed for CO adduct in lipid-free but not in the lipid-bound protein. The presence of the lipid thus appears to inhibit the mobility of CO in the heme pocket. 相似文献
73.
We analyze the influence of surface heterogeneity, inducing a random ζ-potential at the walls in electroosmotic incompressible flows. Specifically, we focus on how surface heterogeneity modifies the physico-chemical processes (transport, chemical reaction, mixing) occurring in microchannel and microreactors. While the macroscopic short-time features associated with solute transport (e.g. chromatographic patterns) do not depend significantly on ζ-potential heterogeneity, spatial randomness in the surface ζ-potential modifies the spectral properties of the advection-diffusion operator, determining different long-term properties of transport/reaction phenomena compared to the homogeneous case. Examples of physical relevance (chromatography, infinitely fast reactions) are addressed. 相似文献
74.
Dr. Andrea Previtali Dr. Wei He Dr. Alessandra Forni Dr. Daniele Malpicci Dr. Elena Lucenti Dr. Daniele Marinotto Prof. Lucia Carlucci Prof. Pierluigi Mercandelli Dr. Marco Aldo Ortenzi Prof. Giancarlo Terraneo Dr. Chiara Botta Prof. Ryan Tsz Kin Kwok Dr. Jacky Wing Yip Lam Prof. Ben Zhong Tang Prof. Elena Cariati 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(67):16690-16700
Organic materials with multiple emissions tunable by external stimuli represent a great challenge. TTPyr, crystallizing in different polymorphs, shows a very rich photophyisics comprising excitation-dependent fluorescence and phosphorescence at ambient conditions, and mechanochromic and thermochromic behavior. Transformation among the different species has been followed by thermal and X-ray diffraction analyses and the emissive features interpreted through structural results and DFT/TDDFT calculations. Particularly intriguing is the polymorph TTPyr(HT), serendipitously obtained at high temperature but stable also at room temperature, whose non-centrosymmetric structure guarantees an SHG efficiency 10 times higher than that of standard urea. Its crystal packing, where only the TT units are strongly rigidified by π-π stacking interactions while the Pyr moieties possess partial conformational freedom, is responsible for the observed dual fluorescence. The potentialities of TTPyr for bioimaging have been successfully established. 相似文献
75.
Tuning the phase transition of ZnO thin films through lithography: an integrated bottom‐up and top‐down processing 下载免费PDF全文
Luca Malfatti Alessandra Pinna Stefano Enzo Paolo Falcaro Benedetta Marmiroli Plinio Innocenzi 《Journal of synchrotron radiation》2015,22(1):165-171
An innovative approach towards the physico‐chemical tailoring of zinc oxide thin films is reported. The films have been deposited by liquid phase using the sol–gel method and then exposed to hard X‐rays, provided by a synchrotron storage ring, for lithography. The use of surfactant and chelating agents in the sol allows easy‐to‐pattern films made by an organic–inorganic matrix to be deposited. The exposure to hard X‐rays strongly affects the nucleation and growth of crystalline ZnO, triggering the formation of two intermediate phases before obtaining a wurtzite‐like structure. At the same time, X‐ray lithography allows for a fast patterning of the coatings enabling microfabrication for sensing and arrays technology. 相似文献
76.
Inside Cover: Rational Design of Carboxyl Groups Perpendicularly Attached to a Graphene Sheet: A Platform for Enhanced Biosensing Applications (Chem. Eur. J. 1/2014) 下载免费PDF全文
77.
Dr. Pushpak Mizar Alessandra Burrelli Erika Günther Martin Söftje Prof. Dr. Umar Farooq Prof. Dr. Thomas Wirth 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(41):13113-13116
A new chiral thiohydantoin catalyst is used for the stereoselective iodoamination of alkenes. N‐iodosuccinimide as the source of the electrophilic iodine is activated by catalytic amounts of different additives which also influence the regioselectivity of some cyclizations. 相似文献
78.
Frontispiece: Picket‐Fence Polythiophene and its Diblock Copolymers that Afford Microphase Separations Comprising a Stacked and an Isolated Polythiophene Ensemble 下载免费PDF全文
79.
Eleonora Bolli Alessandra Fava Saulius Kaciulis Alessio Mezzi Roberto Montanari Alessandra Varone 《Surface and interface analysis : SIA》2020,52(12):1089-1092
Cr martensitic steels are promising materials for structural applications in future nuclear fusion reactors. Because the embrittlement after tempering treatments can be a serious problem, the fracture mode of a steel with 10.5 wt% of Cr treated at 700°C for 18 h has been investigated through Charpy tests in the temperature range from −100°C to +150°C. X-ray photoelectron spectroscopy (XPS) analyses carried out on the fracture surfaces evidenced the segregation of Cr in both ductile and brittle (quasicleavage) fields. The unexpected result indicates that Cr segregation weakens the atomic bonds; thus, the fracture path in both the cases corresponds to the zones with higher Cr content. 相似文献
80.
Yuri A. de Oliveira Só Mônica de Abreu Silva Fernando M. Carvalho Alessandra S. Kiametis Ricardo Gargano 《International journal of quantum chemistry》2020,120(11):e26194
Oxidative stress is an imbalance between the production of free radicals and the antioxidant defenses of the organism. Heart diseases, anemia, inflammation, and neurodegenerative disorders have been associated with this biological condition. Trolox is a notable antioxidant drug similar to vitamin E, and it is used to decrease the oxidative stress or repair the damage caused by it. In this work, the virtual screening technique is applied to identify compounds with antioxidant activities similar to Trolox. The antioxidant activity of these compounds was assessments by the mechanisms of hydrogen atom transfer and single electron transfer. Properties such as bond dissociation enthalpy, adiabatic ionization potential, Gibbs free reaction energy, spin density, highest occupied molecular orbital (HOMO), and GAP (HOMO-LUMO) energies, obtained from the DFT approach, point out to the predominance of the HAT mechanism for the antioxidant action of these compounds. The obtained results contribute to a better understanding of the chemical and physical properties responsible for antioxidant activity and the design of new antioxidant agents. 相似文献