1,720,994 research outputs found
Crystal structure of the wild-type and D30A mutant thioredoxin h of Chlamydomonas reinhardtii and implications for the catalytic mechanism
No full textCrystal structure of the W35A mutant thioredoxin h from Chlamydomonas reinhardtii: the substitution of the conserved active site Trp leads to modifications in the environment of the two catalytic cysteines
No full textFunctional and structural features of the oxyanion hole in a thermophilic esterase from Alicyclobacillus acidocaldarius.
No full textExofacial protein thiols as a route for the internalization of Gd(III)-based complexes for MRI cell labelling
No full textFour novel MRIGd(III)-based probes have been synthesized and evaluated for their labeling properties on cultured cell lines K562, C6, and B16. The labeling strategy relies upon the fact that cells display a large number of reactive exofacial protein thiols (EPTs) that can be exploited as anchorage points for suitably activated MRI probes. The probes are composed of a Gd(III) chelate (based on eitherDO3A or DTPA) connected through a flexible linker to the 2-pyridyldithio chemical function for binding to EPTs. GdDO3A-based chelates could efficiently label cells (up to a level of 1.2 1010 Gd(III) atoms/cell), whereas GdDTPA-based chelates showed poor or no cell labeling ability at all. Among the GdDO3A based compounds, that having the longest spacer (compound GdL1A) showed the best labeling efficacy. The mechanism of EPT mediated cell labeling by GdL1A involves probe internalization without sequestration of the Gd(III) chelate within subcellular structures such as endosomes
Crystallization and preliminary X-ray diffraction studies of Aes acetyl-esterase from Escherichia coli.
No full textCrystal structure of the W35A mutant thioredoxin h from Chlamydomonas reinhardtii: the substitution of the conserved active site Trp leads to modifications in the environment of the two catalytic cysteines
No full textDesign of Weakly Basic Thrombin Inhibitors Incorporating Novel P1 Binding Functions: Molecular and X-ray Crystallographic Studies
No full textDesign of Weakly Basic Thrombin Inhibitors Incorporating Novel P1 Binding Functions: Molecular and X-ray Crystallographic Studies
No full textThe Crystal Structure of an EST2 Mutant Unveils Structural Insights on the H Group of the Carboxylesterase/Lipase Family
No full textIn Vivo Labelling of B16 Melanoma Tumor Xenograft with a Thiol-Reactive Gadolinium Based MRI Contrast Agent
No full textMurine melanoma B16 cells display on the extracellular side of the plasma membrane a large number of reactive protein thiols (exofacial protein thiols, EPTs). These EPTs can be chemically labeled with Gd-DO3A-PDP, a Gd(III)-based MRI contrast agent bearing a 2-pyridinedithio chemical function for the recognition of EPTs. Uptake of gadolinium up to 109 Gd atoms per cell can be achieved. The treatment of B16 cells ex vivo with a reducing agent such as tris(2-carboxyethyl)phosphine (TCEP)
results in an increase by 850% of available EPTs and an increase by 45% of Gd uptake. Blocking EPTs with N-ethylmaleimide (NEM) caused a decrease by 84% of available EPTs and a decrease by 55% of Gd uptake. The amount of Gd taken up by B16 cells is therefore dependent upon the availability of EPTs, whose actual level in turn changes according to the extracellular redox microenvironment. Then Gd-DO3A-PDP has been assessed for the labeling of tumor cells in vivo on B16.F10 melanoma tumor-bearing mice. Gd-DO3A-PDP (or Gd-DO3A as the control) has been injected directly into the tumor region at a dose level of 0.1 μmol and the signal enhancement inMR images followed over time. The washout kinetics of Gd-DO3A-PDP from tumor is very slow if compared to that of control Gd-DO3A, and 48 h post injection, the gadolinium-enhancement is still clearly visible. Therefore, B16 cells can be labeled ex vivo as well as in vivo according to a common EPTs-dependent route, provided that high levels of the thiol reactive probe can be delivered to the tumor
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