Site Directed Spin Labeling
Mostrando 13-24 de 24 artigos, teses e dissertações.
-
13. Site-Directed Spin-Labeling Study of the Light-Harvesting Complex CP29
The topology of the long N-terminal domain (∼100 amino-acid residues) of the photosynthetic Lhc CP29 was studied using electron spin resonance. Wild-type protein containing a single cysteine at position 108 and nine single-cysteine mutants were produced, allowing to label different parts of the domain with a nitroxide spin label. In all cases, the apoprote
The Biophysical Society.
-
14. A method for distance determination in proteins using a designed metal ion binding site and site-directed spin labeling: evaluation with T4 lysozyme.
The use of molecular genetics to introduce both a metal ion binding site and a nitroxide spin label into the same protein opens the use of paramagnetic metalnitroxyl interactions to estimate intramolecular distances in a wide variety of proteins. In this report, a His-Xaa3-His metal ion binding motif was introduced at the N terminus of the long interdomain h
-
15. Structural origins of constitutive activation in rhodopsin: Role of the K296/E113 salt bridge
The intramolecular interactions that stabilize the inactive conformation of rhodopsin are of primary importance in elucidating the mechanism of activation of this and other G protein-coupled receptors. In the present study, site-directed spin labeling is used to explore the role of a buried salt bridge between the protonated Schiff base at K296 in TM7 and it
National Academy of Sciences.
-
16. Osmolyte perturbation reveals conformational equilibria in spin-labeled proteins
Recent evidence suggests that proteins at equilibrium can exist in a manifold of conformational substates, and that these substates play important roles in protein function. Therefore, there is great interest in identifying regions in proteins that are in conformational exchange. Electron paramagnetic resonance spectra of spin-labeled proteins containing the
Wiley Subscription Services.
-
17. Time-resolved EPR studies with DNA photolyase: excited-state FADH0 abstracts an electron from Trp-306 to generate FADH-, the catalytically active form of the cofactor.
Photolyase repairs UV-induced cyclobutane-pyrimidine dimers in DNA by photoinduced electron transfer. The enzyme isolated from Escherichia coli contains 5,10-methenyltetrahydrofolate, which functions as the light-harvesting chromophore, and fully reduced flavin adenine dinucleotide (FAD), which functions as the redox catalyst. During enzyme preparation, the
-
18. Export chaperone SecB uses one surface of interaction for diverse unfolded polypeptide ligands
SecB, a remarkable chaperone involved in protein export, binds diverse ligands rapidly with high affinity and low specificity. Site-directed spin labeling and electron paramagnetic resonance spectroscopy were used to investigate the surface of interaction on the export chaperone SecB. We examined SecB in complex with the unfolded precursor form of outer memb
Wiley Subscription Services.
-
19. Structure of membrane-bound α-synuclein studied by site-directed spin labeling
Many of the proposed physiological functions of α-synuclein, a protein involved in the pathogenesis of Parkinson's disease, are related to its ability to interact with phospholipids. To better understand the conformational changes that occur upon membrane binding of monomeric α-synuclein, we performed EPR analysis of 47 singly labeled α-synuclein derivati
National Academy of Sciences.
-
20. Locations of Arg-82, Asp-85, and Asp-96 in helix C of bacteriorhodopsin relative to the aqueous boundaries.
The amino acids Asp-96, Asp-85, and Arg-82, which are important for proton transport by bacteriorhodopsin, are located in helix C. Site-directed spin labeling has been used to map their positions relative to the aqueous boundaries of the membrane. Selected amino acids in helix C, in the B-C loop on the extracellular side, and in the C-D loop on the intracell
-
21. Structural origin of weakly ordered nitroxide motion in spin-labeled proteins
A disulfide-linked nitroxide side chain (R1) used in site-directed spin labeling of proteins often exhibits an EPR spectrum characteristic of a weakly ordered z-axis anisotropic motion at topographically diverse surface sites, including those on helices, loops and edge strands of β-sheets. To elucidate the origin of this motion, the first crystal structures
Wiley Subscription Services.
-
22. Structure and function in rhodopsin: Topology of the C-terminal polypeptide chain in relation to the cytoplasmic loops*
Cysteine mutagenesis and site-directed spin labeling in the C-terminal region of rhodopsin have been used to probe the local structure and proximity of that region to the cytoplasmic loops. Each of the native amino acids in the sequence T335–T340 was replaced with Cys, one at a time. The sulfhydryl groups of all mutants reacted rapidly with the sulfhydryl
The National Academy of Sciences of the USA.
-
23. Competing ligands stabilize alternate conformations of the energy coupling motif of a TonB-dependent outer membrane transporter
BtuB is a TonB-dependent outer-membrane transporter for vitamin B12 (or cyanocobalamin, CN-Cbl) in Escherichia coli. The binding of CN-Cbl is believed to promote an unfolding or undocking of the Ton box, the conserved N-terminal energy coupling motif at the periplasmic surface of the transporter. This structural change may facilitate the interaction of BtuB
National Academy of Sciences.
-
24. Paramagnetic relaxation enhancements in unfolded proteins: Theory and application to drkN SH3 domain
Site-directed spin labeling in combination with paramagnetic relaxation enhancement (PRE) measurements is one of the most promising techniques for studying unfolded proteins. Since the pioneering work of Gillespie and Shortle (J Mol Biol 1997;268:158), PRE data from unfolded proteins have been interpreted using the theory that was originally developed for ro
Wiley Subscription Services.