Low-Angle X-Ray Diffraction and Electron-Microscope Studies of Isolated Erythrocyte Membranes

1970 ◽  
Vol 7 (2) ◽  
pp. 357-371
Author(s):  
S. KNUTTON ◽  
J. B. FINEAN ◽  
R. COLEMAN ◽  
A. R. LIMBRICK
Keyword(s):  
Erythrocyte Membranes ◽  
Multiphase System ◽  
Type I ◽  
Type Ii ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural Differences ◽  
Diffraction Patterns ◽  
Haemoglobin Content ◽  
Human Erythrocyte Ghost

Two alternative sequences of low angle X-ray diffraction patterns (Type I and Type II) have been observed during the controlled dehydration of rat (and human) erythrocyte ghost preparations in which the residual haemoglobin content has varied. The Type I sequence has been obtained when haemoglobin has comprised more than 30% of the total protein of the membrane preparation. It features an initial lamellar pattern that has been interpreted in terms of a predominantly continuous lipoprotein sandwich structure. Subsequent changes in diffraction pattern have been suggested to represent a partial breakdown of the lipoprotein structure to give a multiphase system. The Type II sequence was most readily obtained from haemoglobin-free ghosts. At no stage during the dehydration of these ghosts did the diffraction feature a stable lamellar pattern. At all levels of hydration the X-ray reflections appeared to represent independent lipid and lipoprotein phases. Osmium tetroxide fixation of haemoglobin-free membranes prevented the separation of lipid and lipoprotein phases during dehydration. Comparisons of electron micrographs of condensed membrane preparations have revealed some structural differences between membranes which give rise to the Type I and Type II diffraction sequences.

Low-Angle X-Ray Diffraction and Electron-Microscope Studies of Isolated Cell Membranes

1966 ◽  
Vol 1 (3) ◽  
pp. 287-296
Author(s):  
J. B. FINEAN ◽  
R. COLEMAN ◽  
W. G. GREEN ◽  
A. R. LIMBRICK
Keyword(s):  
Diffraction Pattern ◽  
Close Packing ◽  
Hexagonal Structure ◽  
Erythrocyte Membranes ◽  
Multiphase System ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns ◽  
Guinea Pig Brain ◽  
Isolated Cell

A sequence of low-angle X-ray diffraction patterns obtained during the controlled drying of a preparation of rat erythrocyte ghosts has been interpreted with the aid of corresponding electron micrographs and of a parallel study of myelin isolated from guinea-pig brain. A diffraction pattern that persists down to a level of 10-20% hydration of the sample is believed to arise from the close packing of native erythrocyte membranes. Each membrane is about 100 Å thick and it is suggested that it consists of a predominantly continuous bimolecular layer of lipid, with non-lipid components associated with both surfaces. Further changes in diffraction pattern which accompany continued drying could be interpreted either as a change from a lamellar to a hexagonal structure or as the formation of a multiphase system. Evidence is put forward to support the latter interpretation.

X-ray structure determination of the monoclinic (121 K) and orthorhombic (85 K) phases of langbeinite-type dithallium dicadmium sulfate

2000 ◽  
Vol 56 (6) ◽  
pp. 921-935 ◽  
Author(s):  
A. Guelylah ◽  
G. Madariaga ◽  
W. Morgenroth ◽  
M. I. Aroyo ◽  
T. Breczewski ◽  
...  
Keyword(s):  
Orthorhombic Symmetry ◽  
Type I ◽  
Type Ii ◽  
Monoclinic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Distortion Analysis ◽  
Precise Analysis ◽  
Monoclinic Distortion

The structures of the monoclinic and the orthorhombic phases of type I langbeinite Tl2Cd2(SO4)3 have been determined at 121 and 85 K, respectively, by X-ray diffraction. A precise analysis of these structures shows the existence of some differences compared to langbeinites of type II. The monoclinic structure differs very little from the high-temperature cubic structure and the distortion relating the monoclinic structure to the cubic one is very small. SO4 tetrahedra seem to rotate under orthorhombic symmetry in the monoclinic phase. A symmetry distortion analysis of the ferroelectric monoclinic distortion discloses the importance of the secondary modes with orthorhombic symmetry, especially for the O atoms of the SO4 groups.

scholarly journals Acemetacin cocrystal structures by powder X-ray diffraction

IUCrJ ◽  
2017 ◽  
Vol 4 (3) ◽  
pp. 206-214 ◽  
Author(s):  
Geetha Bolla ◽  
Vladimir Chernyshev ◽  
Ashwini Nangia
Keyword(s):  
Crystal Structures ◽  
Molecular Electrostatic Potential ◽  
Acid Group ◽  
Mutual Orientation ◽  
Type I ◽  
Type Ii ◽  
Melt Crystallization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrogen Bond Interactions

Cocrystals of acemetacin drug (ACM) with nicotinamide (NAM),p-aminobenzoic acid (PABA), valerolactam (VLM) and 2-pyridone (2HP) were prepared by melt crystallization and their X-ray crystal structures determined by high-resolution powder X-ray diffraction. The powerful technique of structure determination from powder data (SDPD) provided details of molecular packing and hydrogen bonding in pharmaceutical cocrystals of acemetacin. ACM–NAM occurs in anhydrate and hydrate forms, whereas the other structures crystallized in a single crystalline form. The carboxylic acid group of ACM forms theacid–amide dimer three-point synthonR32(9)R22(8)R32(9) with three differentsynamides (VLM, 2HP and caprolactam). The conformations of the ACM molecule observed in the crystal structures differ mainly in the mutual orientation of chlorobenzene fragment and the neighboring methyl group, beinganti(type I) orsyn(type II). ACM hydrate, ACM—NAM, ACM–NAM-hydrate and the piperazine salt of ACM exhibit the type I conformation, whereas ACM polymorphs and other cocrystals adopt the ACM type II conformation. Hydrogen-bond interactions in all the crystal structures were quantified by calculating their molecular electrostatic potential (MEP) surfaces. Hirshfeld surface analysis of the cocrystal surfaces shows that about 50% of the contribution is due to a combination of strong and weak O...H, N...H, Cl...H and C...H interactions. The physicochemical properties of these cocrystals are under study.

X-ray diffraction patterns and anatomical properties of claw tissues of beef and dairy cattle

2007 ◽  
Vol 145 (6) ◽  
pp. 623-633 ◽  
Author(s):  
M. P. BROWNE ◽  
D. W. L. HUKINS ◽  
J. M. S. SKAKLE ◽  
C. H. KNIGHT ◽  
K. A. K. HENDRY ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Dairy Cattle ◽  
Type I ◽  
X Ray Diffraction ◽  
Dorsal Wall ◽  
X Ray ◽  
Dairy Heifers ◽  
Physical Measurements ◽  
Proximal Site ◽  
Diffraction Patterns

SUMMARYMedial claws from the right hind feet were obtained post mortem from four 19–20-month-old beef heifers and from four 28-month-old first-calving dairy heifers 3–4 days postpartum. X-ray diffraction (XRD) studies were undertaken on samples of soft and hard (cornified) integumental tissues of dorsal wall, sole and heel (bulb) for varying sites and planes of exposure. The measurements were interpreted as defining diffraction patterns and intermolecular spacings of cytoskeletal and extracellular fibrous structural proteins. The orientation of these proteins was examined in relation to physical characteristics and function including bearing of body weight by these tissues.Physical measurements taken included impression hardness which showed typically greater values for wall than sole and variable differences between horn of dairy and beef origin and husbandry systems. Claws from dairy heifers had significantly smaller values for toe (dorsal wall) angle, claw height and heel height and thickness of solear horn and heel soft tissue. Although few were studied, the results reflected typical husbandry origins and indicated the susceptibility to the lesion formation well recognized in postpartum dairy cattle.Typical XRD patterns for horn samples showed defined arcs of reflectance on the equatorial axis consistent with findings for the presence of α-helices in fibrils reported to occur in other hard-keratin-containing integumental tissues. However, reflectance on the meridional axis also reported for these other tissues was not detected. A similar defined pattern was obtained for less than 0·10 of samples of internal soft pre-cornified epidermal and attached dermal tissue although the values for intermolecular ‘d’ spacing for these were consistent with those reported for type I collagen. Diffuse reflection patterns were thus evident for the majority of samples of soft tissue epidermis and dermis and also for adipose tissue of the digital cushion.The formation of defined arcs of reflectance allowed the determination of fibril alignment in wall and solear horn. For the orientated samples of dorsal wall horn tissue, the outer layer showed a longitudinal angle of orientation essentially maintained proximal to distal. This pattern was maintained throughout the depth of horn at the proximal site. In contrast, layers in mid-wall and towards the distal edge showed a greater circumferential (horizontal) orientation in sections collected anterior to posterior towards the inner corial, including laminar, tissues. The orientation of fibrils in inner wall horn appears to relate to the direction of load-bearing forces in connecting horn to the distal phalanx. Horizontal alignment of fibrils was observed in the sole. In presenting the long axis of cells to the ground surface this orientation may facilitate erosive forces and contribute to the thinning of cornified sole horn under adverse underfoot conditions.

X-ray diffraction patterns from haemoglobin-free erythrocyte membranes

Nature ◽  
1975 ◽  
Vol 257 (5528) ◽  
pp. 718-719 ◽  
Author(s):  
J. B. FINEAN ◽  
R. FREEMAN ◽  
R. COLEMAN
Keyword(s):  
Erythrocyte Membranes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns

Lactate dehydrogenase from the hyperthermophilic archaeon Methanococcus jannaschii: overexpression, crystallization and preliminary X-ray analysis

2000 ◽  
Vol 56 (1) ◽  
pp. 81-83 ◽  
Author(s):  
Byung Il Lee ◽  
Changsoo Chang ◽  
Seung-Je Cho ◽  
Gye Won Han ◽  
Yeon Gyu Yu ◽  
...  
Keyword(s):  
Type I ◽  
X Rays ◽  
Type Ii ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Protein Mass ◽  
Crystal Volume

L(+)-Lactate dehydrogenase (LDH) is a key enzyme in anaerobic metabolism which converts pyruvate to lactate. LDH from the hyperthermophilic archaebacterium Methanococcus jannaschii has been overexpressed in Escherichia coli and crystallized in two crystal forms at 297 K using 2-methyl-2,4-pentanediol as precipitant. Type I crystals grew rapidly and diffracted to at least 2.8 Å Bragg spacing upon exposure to Cu Kα X-rays. X-ray diffraction data to 2.9 Å have been collected from a native crystal. The type I crystal is tetragonal, belonging to the space group P42212, with unit-cell parameters a = b = 99.74, c = 170.00 Å. The asymmetric unit contains two LDH subunits, with a corresponding crystal volume per protein mass (V m ) of 3.05 Å3 Da−1 and a solvent content of 59.7%. Type II crystals, which grew more slowly, diffracted to at least 1.8 Å Bragg spacing upon exposure to Cu Kα X-rays. X-ray diffraction data to 1.9 Å have been collected from a native crystal. The type II crystal is orthorhombic, belonging to the space group P21212, with unit-cell parameters a = 47.65, b = 125.10, c = 58.08 Å. The asymmetric unit contains a single LDH subunit, with a corresponding crystal volume per protein mass (V m ) of 2.50 Å3 Da−1 and a solvent content of 50.8%. Therefore, the type II crystal is more suitable for high-resolution structure determination than the type I crystal.

Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction

1977 ◽  
Vol 35 ◽  
pp. 330-333
Author(s):  
T. Gulik-Krzywicki ◽  
M.J. Costello
Keyword(s):  
Biological Materials ◽  
Molecular Organization ◽  
X Ray Diffraction ◽  
Glass Capillary ◽  
X Ray ◽  
Rate Dependent ◽  
Before And After ◽  
Freeze Etching ◽  
Diffraction Patterns ◽  
Set Up

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.

Examination of Rabbit Fc Crystals

1968 ◽  
Vol 26 ◽  
pp. 140-141
Author(s):  
J. P. Robinson ◽  
P. G. Lenhert
Keyword(s):  
Molecular Weight ◽  
Flat Plate ◽  
Phosphate Buffer ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
X Ray ◽  
Neutral Ph ◽  
Small Crystals ◽  
Carbon Coated ◽  
Diffraction Patterns

Crystallographic studies of rabbit Fc using X-ray diffraction patterns were recently reported. The unit cell constants were reported to be a = 69. 2 A°, b = 73. 1 A°, c = 60. 6 A°, B = 104° 30', space group P21, monoclinic, volume of asymmetric unit V = 148, 000 A°3. The molecular weight of the fragment was determined to be 55, 000 ± 2000 which is in agreement with earlier determinations by other methods.Fc crystals were formed in water or dilute phosphate buffer at neutral pH. The resulting crystal was a flat plate as previously described. Preparations of small crystals were negatively stained by mixing the suspension with equal volumes of 2% silicotungstate at neutral pH. A drop of the mixture was placed on a carbon coated grid and allowed to stand for a few minutes. The excess liquid was removed and the grid was immediately put in the microscope.

Control of the phase composition of advanced calcium phosphates using an x-ray diffractometer with a curved position-sensitive detector

2020 ◽  
Vol 86 (6) ◽  
pp. 29-35
Author(s):  
V. P. Sirotinkin ◽  
O. V. Baranov ◽  
A. Yu. Fedotov ◽  
S. M. Barinov
Keyword(s):  
Phase Composition ◽  
Calcium Phosphates ◽  
Position Sensitive Detector ◽  
Sensitive Detector ◽  
X Ray Diffraction ◽  
X Ray ◽  
Impurity Phases ◽  
Position Sensitive ◽  
Diffraction Peaks ◽  
Diffraction Patterns

The results of studying the phase composition of advanced calcium phosphates Ca10(PO4)6(OH)2, β-Ca3(PO4)2, α-Ca3(PO4)2, CaHPO4 · 2H2O, Ca8(HPO4)2(PO4)4 · 5H2O using an x-ray diffractometer with a curved position-sensitive detector are presented. Optimal experimental conditions (angular positions of the x-ray tube and detector, size of the slits, exposure time) were determined with allowance for possible formation of the impurity phases during synthesis. The construction features of diffractometers with a position-sensitive detector affecting the profile characteristics of x-ray diffraction peaks are considered. The composition for calibration of the diffractometer (a mixture of sodium acetate and yttrium oxide) was determined. Theoretical x-ray diffraction patterns for corresponding calcium phosphates are constructed on the basis of the literature data. These x-ray diffraction patterns were used to determine the phase composition of the advanced calcium phosphates. The features of advanced calcium phosphates, which should be taken into account during the phase analysis, are indicated. The powder of high-temperature form of tricalcium phosphate strongly adsorbs water from the environment. A strong texture is observed on the x-ray diffraction spectra of dicalcium phosphate dihydrate. A rather specific x-ray diffraction pattern of octacalcium phosphate pentahydrate revealed the only one strong peak at small angles. In all cases, significant deviations are observed for the recorded angular positions and relative intensity of the diffraction peaks. The results of the study of experimentally obtained mixtures of calcium phosphate are presented. It is shown that the graphic comparison of experimental x-ray diffraction spectra and pre-recorded spectra of the reference calcium phosphates and possible impurity phases is the most effective method. In this case, there is no need for calibration. When using this method, the total time for analysis of one sample is no more than 10 min.

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