scholarly journals Spontaneous Adhesion of DOPA and Tryptophan Functionalized PEG to Polystyrene Nanobeads: An EPR Study

2018 ◽  
Vol 915 ◽  
pp. 243-247 ◽  
Author(s):  
Yaman Göksel ◽  
İklima Kırpat ◽  
Yasar Akdogan
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Amino Acid ◽  
Poly Ethylene Glycol ◽  
Paramagnetic Resonance ◽  
Adhesion Mechanism ◽  
Free Condition ◽  
Different Types ◽  
Long Time ◽  
Poly Ethylene ◽  
Electron Paramagnetic

Wet adhesion is achieved by mussels so naturally. Their adhesion mechanism has inspired scientists to obtain wet adhesives for a long time. The amino acid 3,4-dihydroxyphenylalanine (DOPA) produced by mussels adheres to different types of surfaces and also contributes to cohesive interactions. Here, we showed the spontaneous adhesion of DOPA functionalized four armed poly (ethylene glycol) (PEG) polymer to spin labeled polystyrene (SL-PS) nanosurfaces by electron paramagnetic resonance (EPR) spectroscopy. In addition to DOPA, adhesion property of another amino acid of tryptophan (Trp) was studied. Trp attached four armed PEG polymers did not adhere to the surface of SL-PS in the force free condition. However, two armed DOPA and two armed Trp functionalized PEG adhere to the PS.

scholarly journals Coupling of [33S]sulphur to molybdenum(V) in different reduced forms of xanthine oxidase

1981 ◽  
Vol 199 (3) ◽  
pp. 629-637 ◽  
Author(s):  
J P G Malthouse ◽  
G N George ◽  
D J Lowe ◽  
R C Bray
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Xanthine Oxidase ◽  
The Other ◽  
Reduced Form ◽  
Sulphur Atom ◽  
Paramagnetic Resonance ◽  
Different Types ◽  
Resonance Coupling ◽  
Electron Paramagnetic ◽  
Reduced Forms

Different reduced forms of xanthine oxidase, labelled specifically in the cyanide-labile site with 33S, were prepared and examined by electron paramagnetic resonance. Coupling of this isotope to molybdenum(V) was quantified with the help of computer simulations and found to differ markedly from one reduced form to another. The xanthine Very Rapid signal shows strong, highly anisotropic, coupling with A(33S)av. 1.27 mT. For this signal, axes of the g- and A(33S)-tensors are rotated relative to one another. One axis of the A-tensor is in the plane of gxx ang gyy, but rotated by 40 degrees relative to the gxx axis, whereas the direction of weakest coupling to sulphur deviates by 10 degrees from the gzz axis. In contrast with this signal, only rather weaker coupling was observed in different types of Rapid signal [A(33S)av. 0.3--0.4 mT], and in the Inhibited signal coupling was weaker still [A(33S)av. 0.1--0.2 mT]. Clearly, there must be substantial differences in the structures of the molybdenum centre in the different signal-giving species, with the sulphur atom perhaps in an equatorial type of ligand position in the Very Rapid species but in a more axial one in the other species. Structures are discussed in relation to the mechanism of action of the enzyme and the nature of the proton-accepting group that participates in turnover.

Persistent P-Stabilized Boryl Radicals with Bulky Substituents at Boron

Synthesis ◽  
2018 ◽  
Vol 50 (18) ◽  
pp. 3671-3678
Author(s):  
Didier Bourissou ◽  
Amos Rosenthal ◽  
Sonia Mallet-Ladeira ◽  
Ghenwa Bouhadir
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Room Temperature ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Radical Reactivity ◽  
Different Types ◽  
Electron Paramagnetic

Two new P-stabilized boryl radicals [Ph2P(naph)BAr] (Ar = Tip and Ter) have been prepared and characterized by electron paramagnetic resonance spectroscopy. These radicals are persistent for several days in solution at room temperature. The high steric congestion at boron does not prevent radical reactivity. Two different types of dimerization equilibrium have been observed. The structures of the dimers have been unambiguously established by X-ray diffraction crystallography.

scholarly journals A four-iron ferredoxin from Desulfovibrio desulfuricans (Short Communication)

1973 ◽  
Vol 133 (4) ◽  
pp. 851-854 ◽  
Author(s):  
J. A. Zubieta ◽  
R. Mason ◽  
J. R. Postgate
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Absorption Spectrum ◽  
Amino Acid ◽  
Short Communication ◽  
Visible Region ◽  
Desulfovibrio Desulfuricans ◽  
Paramagnetic Resonance ◽  
Desulfovibrio Gigas ◽  
Electron Paramagnetic ◽  
Acid Labile

Ferredoxin from Desulfovibrio desulfuricans was isolated, purified and crystallized. It contains four iron atoms and four sulphido or ‘acid-labile’ sulphur atoms for a molecule of 6000 daltons. The absorption spectrum in the u.v.–visible region and the electron-paramagnetic-resonance signals of the reduced protein are similar to those observed for other four-iron ferredoxins. The amino acid composition is different from that of Desulfovibrio gigas ferredoxin. The redox potential of −0.33V at pH7.0 was determined by dye techniques.

scholarly journals Prediction of favourable sites for spin labelling of proteins

2010 ◽  
Vol 24 (6) ◽  
pp. 651-659 ◽  
Author(s):  
Yevhen Polyhach ◽  
Gunnar Jeschke
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Structural Changes ◽  
Point Mutations ◽  
Paramagnetic Resonance ◽  
Rotamer Library ◽  
Figures Of Merit ◽  
Electron Paramagnetic ◽  
Spin Labelling

Electron paramagnetic resonance studies on diamagnetic proteins are based on site-directed spin labelling and require relatively much effort for engineering cystein point mutations as well as expressing and labelling the protein. Therefore, it is advantageous to predict those sites and pairs of sites that can provide the most precise and most reliable information on accessibility and distances. Systematic site scans based on a rotamer library approach for spin label side groups allow for such predictions. Figures of merit are defined that can be used to rank sites according to their potential suitability in studies of structure and structural changes. Such site scans can still provide useful results if only a backbone model and the amino acid sequence of the protein are known.

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