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Although hydrogens comprise half of the atoms in a protein molecule and are of great importance chemically and structurally, direct visualization of them by using crystallography is difficult. Neutron crystallography is capable of directly revealing the position of hydrogens, but its use on unlabeled samples faces certain technical difficulties: the large(More)
As the first International Tables volume devoted to the crystallography of large biological molecules, Volume F is intended to complement existing volumes of International Tables for Crystallography. A background history of the subject is followed by a concise introduction to the basic theory of X-ray diffraction and other requirements for the practice of(More)
The time-of-flight neutron Laue technique has been used to determine the location of hydrogen atoms in the enzyme d-xylose isomerase (XI). The neutron structure of crystalline XI with bound product, d-xylulose, shows, unexpectedly, that O5 of d-xylulose is not protonated but is hydrogen-bonded to doubly protonated His54. Also, Lys289, which is neutral in(More)
Time-of-flight neutron diffraction has been used to locate hydrogen atoms that define the ionization states of amino acids in crystals of D-xylose isomerase. This enzyme, from Streptomyces rubiginosus, is one of the largest enzymes studied to date at high resolution (1.8 A) by this method. We have determined the position and orientation of a metal ion-bound(More)
Water in close proximity to the protein surface is fundamental to protein folding, stability, recognition and activity. Protein structures studied by diffraction methods show ordered water molecules around some charged, polar, and non-polar (hydrophobic) amino acids, although the later are only observed when they are at the interface between symmetry(More)
Lamellar neutron diffraction from oriented multilayers of hydrated dipalmitoyl lecithin was phased by isomorphous H(2)O-D(2)O exchange and swelling techniques. Bound water sites were located in the polar head group region of the bilayer profile. A 6-A resolution structure based on the neutron scattering density profile is proposed for the bilayer. It is(More)
The advantageous use of neutron scattering techniques for the determination of membrane structures is described. Constituents of biological membranes show much larger differences in their scattering factors for neutrons than for X-rays, permitting the assignment of chemical groups to features in the Fourier map. Deuteration of particular components further(More)
The relative positions of the centers of mass of the 21 proteins of the 30S ribosomal subunit from Escherichia coli have been determined by triangulation using neutron scattering data. The resulting map of the quaternary structure of the small ribosomal subunit is presented, and comparisons are made with structural data from other sources.