scholarly journals Crystal structures of egg-white lysozyme of hen in acetate-free medium and of lysozyme complexes with N-acetylglucosamine and β-methyl N-acetylglucosaminide

1978 ◽  
Vol 173 (2) ◽  
pp. 607-616 ◽  
Author(s):  
S J Perkins ◽  
L N Johnson ◽  
P A Machin ◽  
D C Phillips
Keyword(s):  
Conformational Changes ◽  
Crystal Form ◽  
Egg White ◽  
Real Space ◽  
X Ray Diffraction ◽  
Fourier Synthesis ◽  
X Ray ◽  
Egg White Lysozyme ◽  
Tetragonal Crystal ◽  
Difference Fourier

The binding of beta-methyl N-acetylglucosaminide (betaMeGlcNAc) to egg-white lysozyme of hen in the tetragonal crystal form was studied by X-ray diffraction techniques to a resolution of 0.25 nm. The binding of the beta-methyl glycoside is almost identical with the binding of beta-N-acetylglucosamine (betaGlcNAc). Real-space refinement of the lysozyme-alpha/beta GlcNAc and lysozyme-betaMeGlcNAc complexes allowed preliminary analysis of the conformational changes observed on binding monosaccharide inhibitors, specially in the region involving tryptophan-62 and residues 70–76. Tetagonal lysozyme crystals, grown in the absence of acetate ions, were examined by X-ray diffraction to 0.25nm resolution. The resulting difference Fourier synthesis shows no firm evidence for bound acetate ions and indicates only minor conformational changes in the side-chain positions of aspartic acid-101 and asparagine-103. The close similarity of the lysozyme structures in the presence and absence of acetate is contrary to expectations from previous n.m.r. studies.

scholarly journals Direct Observation of Molecular Orbitals Using Synchrotron X-ray Diffraction

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 998
Author(s):  
Shunsuke Kitou ◽  
Yuto Hosogi ◽  
Ryo Kitaura ◽  
Toshio Naito ◽  
Toshikazu Nakamura ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Real Space ◽  
Molecular Orbitals ◽  
New Method ◽  
C60 Fullerene ◽  
X Ray Diffraction ◽  
Fourier Synthesis ◽  
Orbital State ◽  
X Ray ◽  
Valence Electron Density

The physical properties of molecular crystals are governed by the frontier orbitals of molecules. A molecular orbital, which is formed by superposing the atomic orbitals of constituent elements, has complicated degrees of freedom in the crystal because of the influence of electron correlation and crystal field. Therefore, in general, it is difficult to experimentally observe the whole picture of a frontier orbital. Here, we introduce a new method called “core differential Fourier synthesis” (CDFS) using synchrotron X-ray diffraction to observe the valence electron density in materials. By observing the valence electrons occupied in molecular orbitals, the orbital state can be directly determined in a real space. In this study, we applied the CDFS method to molecular materials such as diamond, C60 fullerene, (MV)I2, and (TMTTF)2X. Our results not only demonstrate the typical orbital states in some materials, but also provide a new method for studying intramolecular degrees of freedom.

The structure of vitamin B 12 . VIII. The crystal structure of vitamin B 12 -5'-phosphate

1970 ◽  
Vol 318 (1533) ◽  
pp. 143-167 ◽  
Keyword(s):  
Crystal Structure ◽  
Phosphate Ester ◽  
Water Molecules ◽  
Vitamin B ◽  
X Ray Diffraction ◽  
Fourier Synthesis ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Vitamin B 12 ◽  
Difference Fourier

The crystal structure of vitamin B 12 -5' -phosphate, a biosynthetic precursor of vitamin B 12 , has been determined by X-ray diffraction methods. The air-dried crystals are orthorhombic, space group P 2 1 2 1 2 1 , with a = 23.72 Å, b = 21.74 Å and c = 16.07 Å. The observed density of 1.362 g cm -3 indicates four vitamin B 12 -5' -phosphate and about sixty water molecules in the unit cell. The X-ray diffraction data to 1.2 Å resolution were collected with a PAILRED linear diffractometer using Cu K α radiation from a silicon monochromator. The structure was solved by using Patterson methods in conjunction with the tangent formula and was refined by Fourier and least-squares methods. The final R value for the 2112 observed reflexions is 16.2 %. The structure is very similar to that found by Hodgkin and co-workers for air-dried vitamin B 12 crystals. The difference Fourier synthesis between this compound and vitamin B 12 shows that two water molecules move into phosphate oxygen positions when the phosphate in the precursor is removed, and one acetamide in contact with these water molecules in the vitamin is rotated out of the way in the phosphate. A second acetamide is also differently oriented in the two crystals. The α -glycosidic bond between the ribose and the dimethylbenzimidazole is 16° out of the plane of the base. The ribose conformation is C2'>- exo , and the phosphate ester conformations are similar to those found in other B 12 crystals.

Improvement of crystal quality for tetragonal hen egg white lysozyme crystals under application of an external alternating current electric field

2013 ◽  
Vol 46 (1) ◽  
pp. 25-29 ◽  
Author(s):  
H. Koizumi ◽  
S. Uda ◽  
K. Fujiwara ◽  
M. Tachibana ◽  
K. Kojima ◽  
...  
Keyword(s):  
Electric Field ◽  
Egg White ◽  
Crystal Quality ◽  
Hen Egg White Lysozyme ◽  
X Ray Diffraction ◽  
Rocking Curve ◽  
X Ray ◽  
Egg White Lysozyme ◽  
Ac Electric Field ◽  
Hen Egg White

X-ray diffraction rocking-curve measurements were performed on tetragonal hen egg white lysozyme (HEWL) crystals grown with and without application of an external alternating current (AC) electric field, and then the crystal quality was assessed by the FWHMs of each rocking-curve profile. The FWHMs for HEWL crystals grown with an external electric field were smaller than those for crystals grown without. In particular, the average FWHM for the 12 12 0 reflection with an external electric field (0.0034°) was significantly smaller than that without (0.0061°). This indicates that the crystal quality of HEWL crystals was improved by application of the external AC electric field. This crystallization technique can be expected to enhance the resolution of protein molecule structure analysis by X-ray diffraction.

Structure determination of di-μ-hydroxo-bis[(2-(2-pyridyl)phenyl-κ2 N,C 1)palladium(II)] by X-ray powder diffractometry

2007 ◽  
Vol 63 (1) ◽  
pp. 75-80 ◽  
Author(s):  
J. Pérez ◽  
J. L. Serrano ◽  
J. M. Galiana ◽  
F. L. Cumbrera ◽  
A. L. Ortiz ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Search Algorithm ◽  
Parallel Tempering ◽  
X Ray Diffraction ◽  
Fourier Synthesis ◽  
X Ray ◽  
Planar Conformation ◽  
Unit Cells ◽  
Difference Fourier

The title compound was synthesized in the form of a powder, and was studied by elemental analysis, IR spectroscopy, thermogravimetry and mass spectroscopy. Its crystal structure was then determined by X-ray powder diffractometry, using X-ray diffraction data collected in the reflection Bragg–Brentano geometry. The methodology followed in the present study to resolve the crystal structure consisted of peak indexing, then the use of the Monte-Carlo/parallel tempering search algorithm, and finally Rietveld refinement coupled with difference-Fourier synthesis. We found that the crystals are composed of monoclinic unit cells, with 1.5 molecules in the asymmetric unit and therefore six molecules per unit cell. In addition, we concluded that the complexes adopt a planar conformation, forming trimers created by groups of parallel molecules.

ESI mass spectrometry and X-ray diffraction studies of adducts between anticancer platinum drugs and hen egg white lysozyme

2007 ◽  
pp. 156-158 ◽  
Author(s):  
Angela Casini ◽  
Guido Mastrobuoni ◽  
Claudia Temperini ◽  
Chiara Gabbiani ◽  
Simona Francese ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Egg White ◽  
Platinum Drugs ◽  
Hen Egg White Lysozyme ◽  
X Ray Diffraction ◽  
X Ray ◽  
Egg White Lysozyme ◽  
Esi Mass Spectrometry ◽  
Hen Egg White ◽  
Hen Egg

scholarly journals Born out of Fire and Ice: Polymorph Studies of the Antiviral Famciclovir

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 129
Author(s):  
Liana Vella-Zarb ◽  
Ulrich Baisch
Keyword(s):  
Variable Temperature ◽  
Chemical Properties ◽  
Crystal Form ◽  
X Ray Diffraction ◽  
Crystal Forms ◽  
X Ray ◽  
Physical Chemical ◽  
Diffraction Patterns ◽  
Crystalline Forms

There is much interest and focus on solid forms of famciclovir. However, in spite of the abundance of reported differences in oral bioavailability, compressibility, and other physical–chemical properties of the various crystal forms of this drug, very little precise structural analysis is available in the literature to date. The form used in the commercial formulation is the anhydrous form I. Patents and patent applications report three different anhydrous crystalline forms on the basis of unindexed powder diffraction patterns. Single-crystal and variable-temperature X-ray diffraction experiments using the commercially available anhydrous form of famciclovir were carried out and led not only to the crystal structure determination of the anhydrous form I, but also to discovery of a new crystal form of anhydrous famciclovir from powder data.

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