@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 = {<p>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.</p>
},
	keywords = {binding},
	isbn = {0027-8424},
	doi = {Doi 10.1073/Pnas.170278897},
	url = {<Go to ISI>://WOS:000088840500026},
	author = {Rubin, S. M. and Spence, M. M. and Goodson, B. M. and Wemmer, D. E. and Pines, A.}
}
@article {393,
	title = {Effects of diffusion on magnetic resonance imaging of laser-polarized xenon gas},
	journal = {Journal of Chemical Physics},
	volume = {108},
	year = {1998},
	note = {J Chem PhysZh114Times Cited:30Cited References Count:24},
	month = {Apr 15},
	pages = {6233-6239},
	abstract = {<p>Molecular diffusion during the application of magnetic field gradients can distort magnetic resonance images. A systematic characterization of these distortions in one dimension was performed using highly spin-polarized xenon gas. By varying the strength of the applied gradient and the geometric dimension of the sample, the evolution of these image distortions between the regimes of strong and weak diffusion was observed. These results are compared with numerical simulations. By directly measuring the displacement distribution of the polarized xenon atoms, it is shown that in the weak-diffusion regime the image distortions originate from the restricted diffusive motion near the sample boundaries, in agreement with previous theoretical work. Additionally, it is shown that the effects of diffusion can be utilized to enhance the contrast between the boundaries and bulk in the images of polarized gas samples, and thus may be exploited as a means of boundary detection in such systems. (C) 1998 American Institute of Physics. [S0021-9606(98)02915-8].</p>
},
	keywords = {xe-129},
	isbn = {0021-9606},
	doi = {Doi 10.1063/1.476030},
	url = {<Go to ISI>://WOS:000073073700018},
	author = {Song, Y. Q. and Goodson, B. M. and Sheridan, B. and de Swiet, T. M. and Pines, A.}
}
