Small-Angle X-ray Scattering Study of Macrophage Migration Inhibitory Factor Complexed with Albumin

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine, which plays a pivotal role in the regulation of immune response. Hence, the search for new inhibitors of MIF tautomerase activity has attracted great attention. This protein is known to serve as a superligand, by involving in protein–protein interactions that are poorly studied. Macrophage migration inhibitory factor was prepared in complex with albumin, and its solution structure was studied. Difficulties encountered in performing this research were due to the fact that the sample was a mixture of the MIF–albumin complex and the individual proteins. The interaction was found to be weak and unstable. Three most probable models of the MIF–albumin complex were obtained using small-angle X-ray scattering and molecular docking simulation, and one of these models was shown to be preferable. One albumin molecule binds to the MIF trimer in the active-site region of the protein.     

In-situ SEOP polarizer and initial tests on a high flux neutron beam

Polarized ³He has shown its unique characteristics in many areas of polarized neutron scattering, its ability to polarize neutrons at short wavelengths, accept wide-angle and divergent beams and low backgrounds enable new classes of experiments. While polarized ³He is not a steady state solution as commonly applied, the benefits have been shown to offset the drawbacks of polarizing and refreshing the polarization in the neutron spin filter cells. As an extension of this work, in-situ polarization using the spin-exchange optical pumping (SEOP) method was explored as a means to construct a system which could be used to polarize ³He in the state used for an effective neutron spin filter to constant polarization while on the neutron beam. An in-situ SEOP polarizer was constructed. This device utilized many devices and principles developed for neutron spin filters which are polarized off the beam line using either SEOP or metastability exchange optical pumping (MEOP) under the same research program. As a collimation of this work effects of extremely high neutron capture flux density incident on the in-situ polarizer were explored.     

Neutron beam effects on spin-exchange-polarized 3He

We have observed depolarization effects when high intensity cold neutron beams are incident on alkali-metal spin-exchange-polarized 3He cells used as neutron spin filters. This was first observed as a reduction of the maximum attainable 3He polarization and was attributed to a decrease of alkali-metal polarization, which led us to directly measure alkali-metal polarization and spin relaxation over a range of neutron fluxes at Los Alamos Neutron Science Center and Institute Laue-Langevin. The data reveal a new alkali-metal spin-relaxation mechanism that approximately scales as sqrt[phi_{n}], where phi_{n} is the neutron capture-flux density incident on the cell. This is consistent with an effect proportional to the concentration of electron-ion pairs but is much larger than expected from earlier work.     

Determination of electron affinity of carbonyl radicals by means of negative ion mass spectrometry

Appearance energies of [M-H](-) ions from carbonyl compounds R-CO-R' (R,R' = H, CH(3), NH(2), OH) have been measured by means of negative ion mass spectrometry in resonant electron capture mode. Values of electron affinity of the corresponding radicals, CH(2)&dbond;C(X)O, NH&dbond;C(X)O and O&dbond;C(X)O, have been determined. Copyright 1999 John Wiley & Sons, Ltd.     

Copper-Induced Oligomerization of Ceruloplasmin

Crystallography Reports - Oligomerization of copper-containing ferroxidase of ceruloplasmin in the presence of protein-unbound copper in a solution has been investigated by small-angle X-ray...     

Measurement of the proton asymmetry parameter in neutron beta decay

The proton asymmetry parameter C in neutron decay describes the angular correlation between neutron spin and proton momentum. In this Letter, the first measurement of this quantity is presented. The result C= -0.2377(26) agrees with the standard model expectation. The coefficient C provides an additional parameter for new and improved standard model tests.