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91.
Taylor M. Courtney Chasity P. Hankinson Trevor J. Horst Alexander Deiters 《Chemical science》2021,12(40):13425
Chemically induced dimerization of FKBP and FRB using rapamycin and rapamycin analogs has been utilized in a variety of biological applications. Formation of the FKBP-rapamycin-FRB ternary complex is typically used to activate a biological process and this interaction has proven to be essentially irreversible. In many cases, it would be beneficial to also have temporal control over deactivating a biological process once it has been initiated. Thus, we developed the first reactive oxygen species-generating rapamycin analog toward this goal. The BODIPY-rapamycin analog BORap is capable of dimerizing FKBP and FRB to form a ternary complex, and upon irradiation with 530 nm light, generates singlet oxygen to oxidize and inactivate proteins of interest fused to FKBP/FRB.Utilization of a ROS-generating chromophore for the development of reversible control of rapamycin-induced protein dimerization via targeted oxidation. 相似文献
92.
93.
Molecular mechanics force field calculations have historically shown significant limitations in modeling the energetic and conformational interconversions of highly substituted furanose rings. This is primarily due to the gauche effect that is not easily captured using pairwise energy potentials. In this study, we present a refinement to the set of torsional parameters in the General Amber Force Field (gaff) used to calculate the potential energy of mono, di-, and gem-fluorinated nucleosides. The parameters were optimized to reproduce the pseudorotation phase angle and relative energies of a diverse set of mono- and difluoro substituted furanose ring systems using quantum mechanics umbrella sampling techniques available in the IpolQ engine in the Amber suite of programs. The parameters were developed to be internally consistent with the gaff force field and the TIP3P water model. The new set of angle and dihedral parameters and partial charges were validated by comparing the calculated phase angle probability to those obtained from experimental nuclear magnetic resonance experiments. 相似文献
94.
F. F. Hopkins W. J. Courtney W. R. Coker C. F. Moore P. Richard 《Zeitschrift für Physik A Hadrons and Nuclei》1971,243(5):446-451
The (p, α) reaction was studied on a208Pb target at 16.475 MeV. Nineteen states were observed in205Tl, up to 3.6 MeV in excitation. Angular distributions were obtained for five strong proton-hole transitions, and DWBA fits made to determinelj values. Results are compared with previous206Pb(t, α)205Tl,206Pb(d,3He)205Tl,205Tl(p, p′), and205Tl(n, n′) work. 相似文献
95.
96.
Lee Courtney Paul A. Sermon Jenny Towers Dost Halepoto Angela F. Danil de Namor Ian R. Collins 《Journal of Sol-Gel Science and Technology》2004,32(1-3):229-236
Work on the development of a Ba2 +-sensitive sol–gel based optical fiber (OF) for use in oil wells is described. The optical fiber (OF) has on its surface a Ba2 + chelating ligand (L) immobilized at a 2–16 wt% loading immobilized in a porous SiO2 sol–gel host. The authors report sol–gel routes to these SiO2 and L/SiO2 nanocomposites and describe their characterization by XPS, fluorescence, NMR, UV-vis and BET methods. They also report on the sol–gel coating and its selectivity to Ba2 +(aq). 相似文献
97.
Beck BJ Aldrich CC Fecik RA Reynolds KA Sherman DH 《Journal of the American Chemical Society》2003,125(16):4682-4683
The unique ability of the pikromycin polyketide synthase (Pik PKS) to generate 12- and 14-membered ring macrolactones presents an opportunity to explore the fundamental processes of polyketide synthesis, specifically, the mechanistic details of the chain extension process. We have overexpressed and purified PikAIII and PikAIV and demonstrated the ability of these proteins to generate triketide lactone products using (14)C-methylmalonyl-CoA as the sole substrate. Monomodular PikAIII generates TKL (1) when reacted alone, and synthesizes TKL (2) upon reaction in combination with PikAIV. Product formation remains dependent on the enzymatic decarboxylation of methylmalonyl-CoA and transfer of the acyl chain within the enzyme rather than acylation by propionyl-CoA from spontaneous decarboxylation. We propose that synthesis of TKL (1) by PikAIII involves iterative assembly of the triketide chain within a PikAIII homodimer analogous to the nonmodular type I PKS systems. 相似文献
98.
Prof. Bhajan Lal Karam B. Idrees Dr. Haomiao Xie Courtney S. Smoljan Saman Shafaie Prof. Timur Islamoglu Prof. Omar K. Farha 《Angewandte Chemie (International ed. in English)》2023,62(16):e202219053
Metal–organic frameworks (MOFs) have been proposed as a promising material for non-thermal chemical separations owing to their high structural diversity and tunability. Here, we report the synthesis of a zinc-based MOF containing a three-dimensional (3D) linker, bicyclo[2.2.2]octane-1,4-dicarboxylic acid, with high thermal stability towards the separation of hexane isomers. The incorporation of the 3D linker enhances the structural stability and provides well-defined pore apertures/channels with sub-Ångstrom precision. This precision allowed for the separation of similarly sized hexane isomers based on subtle differences in their kinetic diameters. Multi-component liquid phase batch experiments confirmed the separation of hexanes mixture into linear, monobranched, and dibranched isomers. This work represents a significant milestone in the construction of stable Zn-based MOFs and the incorporation of 3D linkers as a potential solution to challenging separations. 相似文献
99.
Younker JM Krest CM Jiang W Krebs C Bollinger JM Green MT 《Journal of the American Chemical Society》2008,130(45):15022-15027
The class Ic ribonucleotide reductase from Chlamydia trachomatis ( Ct) uses a stable Mn(IV)/Fe(III) cofactor to initiate nucleotide reduction by a free-radical mechanism. Extended X-ray absorption fine structure (EXAFS) spectroscopy and density functional theory (DFT) calculations are used to postulate a structure for this cofactor. Fe and Mn K-edge EXAFS data yield an intermetallic distance of approximately 2.92 A. The Mn data also suggest the presence of a short 1.74 A Mn-O bond. These metrics are compared to the results of DFT calculations on 12 cofactor models derived from the crystal structure of the inactive Fe 2(III/III) form of the protein. Models are differentiated by the protonation states of their bridging and terminal OH X ligands as well as the location of the Mn(IV) ion (site 1 or 2). The models that agree best with experimental observation feature a mu-1,3-carboxylate bridge (E120), terminal solvent (H 2O/OH) to site 1, one mu-O bridge, and one mu-OH bridge. The site-placement of the metal ions cannot be discerned from the available data. 相似文献
100.