@article {313, title = {Distinguishing multiple chemotaxis Y protein conformations with laser-polarized Xe-129 NMR}, journal = {Protein Science}, volume = {14}, year = {2005}, note = {Protein Sci907SSTimes Cited:23Cited References Count:27}, month = {Apr}, pages = {848-855}, abstract = {

The chemical shift of the Xe-129 NMR signal has been shown to be extremely sensitive to the local environment around the atom and has been used to follow processes such as ligand binding by bacterial periplasmic binding proteins. Here we show that the Xe-129 shift can sense more subtle changes: magnesium binding, BeF3- activation, and peptide binding by the Escherichia coli chemotaxis Y protein. H-1-N-15 correlation spectroscopy and X-ray crystallography were used to identify two xenon-binding cavities in CheY that are primarily responsible for the shift changes. One site is near the active site, and the other is near the peptide binding site.

}, keywords = {cavity}, isbn = {0961-8368}, doi = {Doi 10.1110/Ps.041231005}, url = {://WOS:000227738900002}, author = {Lowery, T. J. and Doucleff, M. and Ruiz, E. J. and Rubin, S. M. and Pines, A. and Wemmer, D. E.} } @article {333, title = {Design of a conformation-sensitive xenon-binding cavity in the ribose-binding protein}, journal = {Angewandte Chemie-International Edition}, volume = {43}, year = {2004}, note = {Angew Chem Int Edit877MVTimes Cited:10Cited References Count:20}, pages = {6320-6322}, keywords = {probe}, isbn = {1433-7851}, doi = {Doi 10.1002/Anie.200460629}, url = {://WOS:000225575600015}, author = {Lowery, T. J. and Rubin, S. M. and Ruiz, E. J. and Pines, A. and Wemmer, D. E.} } @article {325, title = {Development of a functionalized xenon biosensor}, journal = {Journal of the American Chemical Society}, volume = {126}, year = {2004}, note = {J Am Chem Soc872UHTimes Cited:60Cited References Count:76}, month = {Nov 24}, pages = {15287-15294}, abstract = {

NMR-based biosensors that utilize laser-polarized xenon offer potential advantages beyond current sensing technologies. These advantages include the capacity to simultaneously detect multiple analytes, the applicability to in vivo spectroscopy and imaging, and the possibility of \"remote\" amplified detection. Here, we present a detailed NMR characterization of the binding of a biotin-derivatized caged-xenon sensor to avidin. Binding of \"functionalized\" xenon to avidin leads to a change in the chemical shift of the encapsulated xenon in addition to a broadening of the resonance, both of which serve as NMR markers of ligand-target interaction. A control experiment in which the biotin-binding site of avidin was blocked with native biotin showed no such spectral changes, confirming that only specific binding, rather than nonspecific contact, between avidin and functionalized xenon leads to the effects on the xenon NMR spectrum. The exchange rate of xenon (between solution and cage) and the xenon spin-lattice relaxation rate were not changed significantly upon binding. We describe two methods for enhancing the signal from functionalized xenon by exploiting the laser-polarized xenon magnetization reservoir. We also show that the xenon chemical shifts are distinct for xenon encapsulated in different diastereomeric cage molecules. This demonstrates the potential for tuning the encapsulated xenon chemical shift, which is a key requirement for being able to multiplex the biosensor.

}, keywords = {drug discovery}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja0483037}, url = {://WOS:000225233600051}, author = {Spence, M. M. and Ruiz, E. J. and Rubin, S. M. and Lowery, T. J. and Winssinger, N. and Schultz, P. G. and Wemmer, D. E. and Pines, A.} } @article {354, title = {Detection and characterization of xenon-binding sites in proteins by Xe-129 NMR spectroscopy}, journal = {Journal of Molecular Biology}, volume = {322}, year = {2002}, note = {J Mol Biol597PTTimes Cited:53Cited References Count:54}, month = {Sep 13}, pages = {425-440}, abstract = {

Xenon-binding sites in proteins have led to a number of applications of xenon in biochemical and structural studies. Here we further develop the utility of Xe-129 NMR in characterizing specific xenon-protein interactions. The sensitivity of the Xe-129 chemical shift to its local environment and the intense signals attainable by optical pumping make xenon a useful NMR reporter of its own interactions with proteins. A method for detecting specific xenon-binding interactions by analysis of Xe-129 chemical shift data is illustrated using the maltose binding protein (MBP) from Escherichia coli as an example. The crystal structure of MBP in the presence of 8 atm of xenon confirms the binding site determined from NMR data. Changes in the structure of the xenon-binding cavity upon the binding of maltose by the protein can account for the sensitivity of the Xe-129 chemical shift to MBP conformation. Xe-129 NMR data for xenon in solution with a number of cavity containing phage T4 lysozyme mutants show that xenon can report on cavity structure. In particular, a correlation exists between cavity size and the binding-induced Xe-129 chemical shift. Further applications of Xe-129 NMR to biochemical assays, including the screening of proteins for xenon binding for crystallography are considered. (C) 2002 Elsevier Science Ltd. All rights reserved

}, keywords = {nonpolar cavity}, isbn = {0022-2836}, doi = {Doi 10.1016/S0022-2836(02)00739-8}, url = {://WOS:000178230500014}, author = {Rubin, S. M. and Lee, S. Y. and Ruiz, E. J. and Pines, A. and Wemmer, D. E.} } @article {366, title = {Characterization of the effects of nonspecific xenon-protein interactions on Xe-129 chemical shifts in aqueous solution: Further development of xenon as a biomolecular probe}, journal = {Journal of Magnetic Resonance}, volume = {152}, year = {2001}, note = {J Magn Reson472QDTimes Cited:37Cited References Count:34}, month = {Sep}, pages = {79-86}, abstract = {

The sensitivity of Xe-129 chemical shifts to weak nonspecific xenon-protein interactions has suggested the use of xenon to probe biomolecular structure and interactions. The realization of this potential necessitates a further understanding of how different macromolecular properties influence the Xe-129 chemical shift in aqueous solution. Toward this goal, we have acquired Xe-129 NMR spectra of xenon dissolved in amino acid, peptide, and protein solutions under both native and denaturing conditions. In general, these cosolutes induce Xe-129 chemical shifts that are downfield relative to the shift in water, as they deshield the xenon nucleus through weak, diffusion-mediated interactions. Correlations between the extent of deshielding and molecular properties including chemical identity, structure, and charge are reported. Xenon deshielding was found to depend linearly on protein size under denaturing solution conditions; the denaturant itself has a characteristic effect on the Xe-129 chemical shift that likely results from a change in the xenon solvation shell structure. In native protein solutions, contributions to the overall Xe-129 chemical shift arise from the presence of weak xenon binding either in cavities or at the protein surface. Potential applications of xenon as a probe of biological systems including the detection of conformational changes and the possible quantification of buried surface area at protein-protein interfaces are discussed. (C) 2001 Academic Press.

}, keywords = {gas}, isbn = {1090-7807}, doi = {Doi 10.1006/Jmre.2001.2389}, url = {://WOS:000170995700009}, author = {Rubin, S. M. and Spence, M. M. and Pines, A. and Wemmer, D. E.} } @article {367, title = {Detection of a conformational change in maltose binding protein by Xe-129 NMR spectroscopy}, journal = {Journal of the American Chemical Society}, volume = {123}, year = {2001}, note = {J Am Chem Soc467XNTimes Cited:28Cited References Count:28}, month = {Sep 5}, pages = {8616-8617}, keywords = {blood}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja0110325}, url = {://WOS:000170729200029}, author = {Rubin, S. M. and Spence, M. M. and Dimitrov, I. E. and Ruiz, E. J. and Pines, A. and Wemmer, D. E.} } @article {364, title = {Functionalized xenon as a biosensor}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {98}, year = {2001}, note = {P Natl Acad Sci USA472CZTimes Cited:112Cited References Count:29}, month = {Sep 11}, pages = {10654-10657}, abstract = {

The detection of biological molecules and their interactions is a significant component of modern biomedical research. In current biosensor technologies, simultaneous detection is limited to a small number of analytes by the spectral overlap of their signals. We have developed an NMR-based xenon biosensor that capitalizes on the enhanced signal-to-noise, spectral simplicity, and chemical-shift sensitivity of laser-polarized xenon to detect specific biomolecules at the level of tens of nanomoles. We present results using xenon \"functionalized\" by a biotin-modified supramolecular cage to detect biotin-avidin binding. This biosensor methodology can be extended to a multiplexing assay for multiple analytes.

}, keywords = {mri}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.191368398}, url = {://WOS:000170966800030}, author = {Spence, M. M. and Rubin, S. M. and Dimitrov, I. E. and Ruiz, E. J. and Wemmer, D. E. and Pines, A. and Yao, S. Q. and Tian, F. and Schultz, P. G.} } @article {375, title = {Evidence of nonspecific surface interactions between laser-polarized xenon and myoglobin in solution}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {97}, year = {2000}, note = {P Natl Acad Sci USA345XMTimes Cited:40Cited References Count:35}, month = {Aug 15}, pages = {9472-9475}, abstract = {

The high sensitivity of the magnetic resonance properties of xenon to its local chemical environment and the large Xe-129 NMR signals attainable through optical pumping have motivated the use of xenon as a probe of macromolecular structure and dynamics. In the present work, we report evidence for nonspecific interactions between xenon and the exterior of myoglobin in aqueous solution, in addition to a previously reported internal binding interaction. Xe-129 chemical shift measurements in denatured myoglobin solutions and under native conditions with varying xenon concentrations confirm the presence of nonspecific interactions. Titration data are modeled quantitatively with treatment of the nonspecific interactions as weak binding sites. Using laser-polarized xenon to measure Xe-129 spin-lattice relaxation times (T-1), we observed a shorter T-1 in the presence of 1 mM denatured apomyoglobin in 6 M deuterated urea (T-1 = 59 +/- 1 s) compared with that in 6 M deuterated urea alone (T-1 = 291 +/- 2 s), suggesting that nonspecific xenon-protein interactions can enhance Xe-129 relaxation. An even shorter T1 was measured in ? mM apomyoglobin in D2O (T-1 = 15 +/- 0.3 s), compared with that in D2O alone (T-1 = 506 +/- 5 s). This difference in relaxation efficiency likely results from couplings between laser-polarized xenon and protons in the binding cavity of apomyoglobin that may permit the transfer of polarization between these nuclei via the nuclear Overhauser effect.

}, keywords = {binding}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.170278897}, url = {://WOS:000088840500026}, author = {Rubin, S. M. and Spence, M. M. and Goodson, B. M. and Wemmer, D. E. and Pines, A.} }