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Atomic Force Microscope Force Spectroscopy
Published in Yuri L. Lyubchenko, An Introduction to Single Molecule Biophysics, 2017
Eric A. Josephs, Piotr E. Marszalek, Zackary N. Scholl
Thioredoxins are enzymes that catalyze the reduction of disulfide (S–S) bonds, which can form between two cysteine (Cys) residues, and are involved in a multitude of cellular processes. These enzymes are evolutionarily widespread, being present in bacteria as well as in higher organisms through plants and mammals, but possess a conserved Cys-X-X-Cys motif in their active site. Biochemical data suggested that the reduction of disulfide bonds by thioredoxins proceeded via an SN2 mechanism (i.e., a bimolecular nucleophilic substitution reaction). However, why different thioredoxins catalyzed this reaction at different rates, and how these differences depended on the specific amino acid sequence and structure of the different thioredoxins, remained unclear (Perez-Jimenez et al. 2009). The Fernandez group, using SMFS using an AFM as a force clamp, was able to monitor the states of individual disulfide bonds in the presence of thioredoxin—first to characterize the chemical mechanisms of bacterial (Escherichia coli) thioredoxin, and then a number of evolutionary divergent thioredoxins. Using this technique, they could identify and differentiate a number of catalytic mechanisms by their modulation of different forces applied to the disulfide bonds. Together with computational modeling, the origin of the diversity of reaction rates and mechanisms by thioredoxins could be directly investigated (four bacterial-origin thioredoxins, and four eukaryotic-origin thioredoxins).
Differential Protein Expression Following JP-8 Jet Fuel Exposure
Published in Mark L. Witten, Errol Zeiger, Glenn D. Ritchie, Jet Fuel Toxicology, 2010
Frank A. Witzmann, Mark L. Witten
Exposure to JP-8 (2,500 mg/m3) resulted in a 66% increase in the expression of GSTP1 over the unexposed group (35% by 1,000 mg/m3), confirming JP-8 lung toxicity. Further confirmation was provided by increased expression of hsp84 (murine hsp90), a constitutive cytoplasmic protein induced in response to various biological stresses as well as chemical exposure in the lung [3]. The moderate induction (8%, p < 0.01) was observed in one of the more abundant cytoplasmic proteins resolved. This reduction was seen in thioether S-methyltransferase, an important enzyme in the metabolism of sulfur- and selenium-containing compounds [47]. JP-8 exposure also reduced the expression of thiol-specific antioxidant thioredoxin peroxidase 1 by more than 50%. Thioredoxin peroxidase 1 catalyzes the removal of thiyl radicals before they generate more reactive radicals, thereby protecting biomolecules from oxidative damage [82]. The observed down-regulation may increase the risk of oxidative damage to the lung during JP-8 and other toxicant exposure.
Design, synthesis, and screening for the antiproliferative activity of new 1,3,4-thiadiazole scaffold linked to substituted phenacyl derivatives and disulfides
Published in Journal of Sulfur Chemistry, 2022
Yang Liu, Junjie Li, Xuguang Liu, Zijian Li, Yanle Men, Yongyue Sun, Baoquan Chen
In addition, thioredoxin (Trx) can be used as a new target for tumor therapy and has significant clinical implications [22]. For instance, 1-methylpropyl 2-imidazolyl disulfide (PX-12) is the first disulfide antitumor drug to enter clinical research in the world. It covalently binds with cysteine residues in Trx to form mixed disulfide to reduce the concentration of thioredoxin reductase (TrxR) in cells, thus inhibiting the thioredoxin system [23–27]. Consequently, we assume that the synthesis of a series of small molecular disulfides can effectively inhibit the proliferation of cancer cells (Figure 1).
Conditioned medium from the three-dimensional culture of human umbilical cord perivascular cells accelerate the migration and proliferation of human keratinocyte and fibroblast
Published in Journal of Biomaterials Science, Polymer Edition, 2018
Min Ho Kim, Wen Hao Wu, Jee Hyun Choi, Ji Hyun Kim, Seok-Ho Hong, Jin Hyun Jun, Yong Ko, Jong Hun Lee
Although a significant difference was not detected in the proliferation of HDFs, the PVC-conditioned medium obtained from a more physiological environment was more effective in the proliferation and migration tests of cell lines than PVC-CM-2D (Figures 3, 4), suggesting that the two systems have different protein profiles. This finding led to further analyses of PVC-CM using 2D electrophoresis and MALDI-TOF (Figure 5, Table 1). PVC-CM-3D contained higher amounts of type I collagen and myosin heavy chain than PVC-CM-2D. The collagen provides cells with environments that mimic the extracellular matrix (ECM) of human skin; ECM has been regarded as very important for cellular adhesion, proliferation, and migration. It is therefore believed that this protein affects the proliferation and migration of keratinocytes and fibroblasts. KIAA0465, N-RAP, and thioredoxin are exclusively expressed in PVC-CM-3D. KIAA0465, which is also called ‘MACF1’, is a member of a family of proteins that form bridges between different cytoskeletal elements. This protein facilitates actin-microtubule interactions at the cell periphery and couples the microtubule network to cellular junctions. Moreover, KIAA0465 is involved in the organization of the cytoskeleton [30], tissue repair [31], and vertebrate development [32]. N-RAP is a nebulin family member that acts as an organizing center for the initial recruitment and assembly of sarcomeric actin filaments and Z-discs [33]. Thioredoxins are proteins that act as antioxidants by facilitating the reduction of other proteins by cysteine thiol-disulfide exchange. Thioredoxins are found in nearly all known organisms and are essential for life in mammals [34]. Recently, Telorack et al. (2016) reported that a glutathione-Nrf2-thioredoxin cross-talk ensures keratinocyte survival and efficient wound repair [35]. These reports indicate that type I collagen, KIAA0465, N-RAP, and thioredoxin are involved not only in the proliferation, migration, and adhesion of human keratinocytes and fibroblasts, but also in the wound-healing process.