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Selected Applications of Laser-Induced Fluorescence Spectroscopy
Published in Helmut H. Telle, Ángel González Ureña, Laser Spectroscopy and Laser Imaging, 2018
Helmut H. Telle, Ángel González Ureña
In this respect, Czar et al. (2015) reported the first FRET measurements of a gaseous ionized protein, a 59-residue variant of the immunoglobulin G-binding domain of protein G (GB1). This protein has a common structural motif, composed of a four-stranded ß-sheet, which is spanned by a single α-helix, thus forming a densely packed hydrophobic core (as shown schematically at the top of Figure 10.16). Although both the structural and dynamic properties of GB1 had been studied in the condensed phase, there was no information about its structure in the gas phase. In their study, the authors investigated the FRET efficiency (ET) of the gaseous protein, as a function of charge state, by measuring both the dispersed and time-resolved fluorescence from the donor dye. The derived gas-phase FRET efficiencies and distance constraints were compared with the results from solution-phase single-molecule FRET experiments to obtain insight into the structural desolvated protein.
Antihypertensive Drugs: Controlling Blood Pressure
Published in Richard J. Sundberg, The Chemical Century, 2017
Examination of Figure 14.1 suggests another possible point of control of the RAAS, namely inhibition of renin itself. This objective has been recognized since the 1970s and became especially relevant when it was observed that both the ACE and ARB classes of drugs induce a feedback mechanism that increases renin concentration. As a result there have been extensive efforts to identify drugs that would be DRI. Renin is an aspartic acid peptidase and its crystal structure and several complexes with inhibitors became available around 1990. This permitted structurally modeling to identify molecules that might act as inhibitors. Most attention was focused on peptidomimetics, which are structures that resemble peptide substrates but are not susceptible to hydrolysis. This is a theme that is applicable to many areas of drug design and several structural motifs that can act as peptidomimetics have been identified.
In situ atomic force microscopy as a tool for investigating assembly of protein matrices
Published in Elaine DiMasi, Laurie B. Gower, Biomineralization Sourcebook, 2014
Sungwook Chung, James J. De Yoreo
Self-assembled protein architectures exhibit a range of structural motifs (Mann 2008) including particles (Johnson 2008), bers (Rambaran and Serpell 2008), ribbons (Du et al. 2005), and sheets (Tanaka et al. 2008). eir functions include selective transport (Tanaka et al. 2008), structural sca olding (Engelhardt 2007), mineral templating (Du et al. 2005; Schultzelam and Beveridge 1994), and propagation of or protection from pathogenesis (Cherny and Gazit 2008; Rambaran and Serpell 2008). Although the molecular structures of the isolated proteins dictate their governing interactions, these functions emerge from the nanoscale organization that arises out of self-assembly. Typically, proteins that naturally self-assemble into extended ordered structures adopt conformations that are distinct from those of the individual monomeric proteins (Chiti and Dobson 2009; Salgado et al. 2008; Schoen et al. 2011; Shoulders and Raines 2009). For example, as discussed previously, collagen matrices, which constitute monomeric sca olds of bones and teeth in all higher organisms, are constructed from triple helices of the individual collagen monomers (Shoulders and Raines 2009). These helices further assemble into highly organized twisted brils exhibiting a pseudohexagonal symmetry. In some cases, assembly is inexorably linked to folding transformations, as in the case of prion or amyloid brils, where misfolding of the monomers triggers assembly, which in turn drives misfolding of new monomers (Chiti and Dobson 2009). Nonetheless, while the phenomenon of folding by individual proteins has been well explained both experimentally and theoretically, much less attention has been given to protein assembly, and the role of folding transformations in de ning the assembly pathway is largely unexplored.
Combining benzotriazoles and azides in copper(II) chemistry: synthesis, structural and spectroscopic characterization of a 1-D corrugated tape [Cu(N3)2(1-Mebta)]n coordination polymer (1-Mebta = 1-methylbenzotriazole)
Published in Journal of Coordination Chemistry, 2021
Gerasimi Lazari, Spyridon Grammatikopoulos, Spyros P. Perlepes, Theocharis C. Stamatatos
We have herein reported the synthesis, crystal structure and spectroscopic characterization of a new 1-D coordination polymer of Cu(II) with an unusual corrugated tape structural motif, which is ensembled by end-on bridging azides and terminally coordinated 1-Mebta groups. The latter are arranged into a parallel, face-to-face conformation, thus providing additional thermodynamic stability to the compound through strong intra-chain π-π stacking interactions. Complex 1 is the first azido-bridged compound of any metal that contains 1-Mebta coordinated ligands and the first copper(II) azido complex with any benzotriazole ligand, and therefore our future research endeavors are oriented towards the development of this chemistry to other 3d- or 4f-metal ions with potentially exciting magnetic, optical and catalytic properties.
Zero/one-dimensional coordination complexes constructed from the carboxylate and multi-nitrogen chelating ligands: structural insights and photocatalytic degradation of organic dye
Published in Inorganic and Nano-Metal Chemistry, 2020
Su-Peng Xu, Feng-Ting Qin, An-Xiong Zheng, Jiang-Tao Li
Solvothermal reaction of Co(NO3)2·6H2O, bimb and H2cbba in a mixed solvent of DMF and 1,2-dichlorobenzene with the presence of NaOH as the pH modulator affords the targeted complex 1 as pink block crystals. The chemical formula of 1 is established to be [Co(cbba)(bimb)](H2O) based on the single crystal X-ray diffraction as well as elemental analysis results. The structural solution and refinement results based on the single crystal data collected around room temperature show that complex 1 crystallizes in the centrosymmetric triclinic space group P-1 and has a 0 D structure. The basic molecular repeating unit of complex 1 is shown in the Figure 1a, which reveal that there are one crystallography independent Co(II) ion, one fully deprotonated cbba2- ligand, one chelating bimb ligand as well as one lattice water molecule, which contribute to the half of the structural motif. The coordination surrounding of the Co(II) ion could be described as a distorted [CoN4O2] octahedron, which is completed by four N atoms from the chelating bimb ligand and two O atoms from two cbba2- ligand. The Co(II)-O bond distances are in the range of 2.130(4) to 2.175(4) Å and the Co(II)-N bond lengths are with the scope of 2.288(5) to 2.338(5) Å, which are comparable with those observed in other Co(II)-containing coordination complexes based on the N,O-donor ligands [15,16]. Two V-shape cbba2- ligands connect with two Co(bimb) motifs to form the molecular structure of 1, in which the two carboxylate groups are in the μ1-η1: η0 pattern (Figure 1b). In addition, the neighboring mononuclear ones are bound together by hydrogen bonds (N6-H6···O2, distance of 1.776 Å) to form a one-dimensional supramolecular structure (Figure 1c).