scholarly journals Laue diffraction as a tool in dynamic studies: hydrolysis of a transiently stable intermediate in catalysis by trypsin

1992 ◽  
Vol 340 (1657) ◽  
pp. 285-300 ◽  
Keyword(s):  
Careful Analysis ◽  
Crystal Quality ◽  
Laue Diffraction ◽  
X Ray ◽  
Multiple Exposures ◽  
Dynamic Studies ◽  
Stable Intermediate ◽  
Structure Determinations ◽  
Ph Jump ◽  
Hydrolysis Of

A transiently stable intermediate in trypsin catalysis, guanidinobenzoyl-Ser-195 trypsin, can be trapped and then released by control of the pH in crystals of the enzyme. This effect has been investigated by static and dynamic white-beam Laue crystallography. Comparison of structures determined before and immediately after a pH jump reveals the nature of concerted changes that accompany activation of the enzyme. Careful analysis of the results of several structure determinations gives information about the reliability of Laue results in general. A study of multiple exposures taken under differing conditions of beam intensity, crystal quality, and temperature revealed information about ways to control damage of specimens by the X-ray beam.

The hydrolytic water molecule in trypsin, revealed by time-resolved Laue crystallography

Science ◽  
1993 ◽  
Vol 259 (5095) ◽  
pp. 669-673 ◽  
Author(s):  
PT Singer ◽  
A Smalas ◽  
RP Carty ◽  
WF Mangel ◽  
RM Sweet
Keyword(s):  
Water Molecule ◽  
Three Dimensional ◽  
Initial Step ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Density Maps ◽  
Before And After ◽  
Ph Jump ◽  
Hydrolysis Of

Crystals of bovine trypsin were acylated at the reactive residue, serine 195, to form the transiently stable p-guanidinobenzoate. Hydrolysis of this species was triggered in the crystals by a jump in pH. The hydrolysis was monitored by three-dimensional Laue crystallography, resulting in three x-ray diffraction structures, all from the same crystal and each representing approximately 5 seconds of x-ray exposure. The structures were analyzed at a nominal resolution of 1.8 angstroms and were of sufficient quality to reproduce subtle features in the electron-density maps for each of the structures. Comparison of the structures before and after the pH jump reveals that a water molecule has positioned itself to attack the acyl group in the initial step of the hydrolysis of this transient intermediate.

Crystal-Structures of cis-(N-Base)Chlorobis-(Ethane-1,2-Diamine)Cobalt(III) Dichloride (N-Base = Ammonia, Pyridine)

1986 ◽  
Vol 39 (2) ◽  
pp. 339 ◽  
Author(s):  
JM Harrowfield ◽  
BW Skelton ◽  
AH White ◽  
FR Wilner
Keyword(s):  
Crystal Structures ◽  
Base Hydrolysis ◽  
X Ray Diffraction ◽  
Nitrogen Base ◽  
Full Matrix ◽  
X Ray ◽  
Steric Crowding ◽  
Structure Determinations ◽  
Hydrolysis Of ◽  
Least Squares Techniques

The crystal structures of the two title compounds, cis-[Co(en)2(NH3) Cl ] Cl2, (1), and cis-[Co(en)2( py ) Cl ]Cl2.H2O, (2), have been determined by single-crystal X-ray diffraction methods at 295 K, being refined by full-matrix least-squares techniques to residuals of 0.025 and 0.036 for 1744 and 3243 independent 'observed' reflections. Crystals of (1) and (2) are monoclinic, P21/c, Z = 4. For (1), a 7.499(1), b 11.986(2), c 14.325(3)Ǻ, β 111.45(1)°; for (2), a 7.617(2), b 12.866(3), c 16.561(5), β 97.33(2)°. Both complexes are racemates with cation conformations Δ( δ,λ ), (1), and Δ( λ,λ ), (2). The structure determinations suggest that variations in the rate of base hydrolysis of these complexes and their imidazole analogue may be correlated with the degree of steric crowding associated with the introduction of the monodentate nitrogen base into the coordination sphere.

scholarly journals In situserial Laue diffraction on a microfluidic crystallization device

2014 ◽  
Vol 47 (6) ◽  
pp. 1975-1982 ◽  
Author(s):  
Sarah L. Perry ◽  
Sudipto Guha ◽  
Ashtamurthy S. Pawate ◽  
Robert Henning ◽  
Irina Kosheleva ◽  
...  
Keyword(s):  
Structural Dynamics ◽  
Free Electron ◽  
Room Temperature ◽  
Free Electron Lasers ◽  
Biochemical Reactions ◽  
Laue Diffraction ◽  
X Ray ◽  
Experimental Strategy ◽  
Dynamic Studies ◽  
Serial Crystallography

Renewed interest in room-temperature diffraction has been prompted by the desire to observe structural dynamics of proteins as they function. Serial crystallography, an experimental strategy that aggregates small pieces of data from a large uniform pool of crystals, has been demonstrated at synchrotrons and X-ray free-electron lasers. This work utilizes a microfluidic crystallization platform for serial Laue diffraction from macroscopic crystals and proposes that a collection of small slices of Laue data from many individual crystals is a realistic solution to the difficulties in dynamic studies of irreversible biochemical reactions.

Identification of acid-insoluble filter-plugging compounds and optimal acid-washing procedures for tubular backpulse pressure filters

TAPPI Journal ◽  
2011 ◽  
Vol 10 (1) ◽  
pp. 17-23
Author(s):  
KEVIN TAYLOR ◽  
RICH ADDERLY ◽  
GAVIN BAXTER
Keyword(s):  
Calcium Sulfate ◽  
Membrane Filter ◽  
Sulfamic Acid ◽  
Xrd Analysis ◽  
Metal Sulfides ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gypsum Formation ◽  
Acid Washing ◽  
Hydrolysis Of

Over time, performance of tubular backpulse pressure filters in kraft mills deteriorates, even with regular acid washing. Unscheduled filter replacement due to filter plugging results in significant costs and may result in mill downtime. We identified acid-insoluble filter-plugging materials by scanning electron microscope/energy-dispersion X-ray spectroscopy (SEM/EDS) and X-ray diffraction (XRD) analysis in both polypropylene and Gore-Tex™ membrane filter socks. The major filter-plugging components were calcium sulfate (gypsum), calcium phosphate (hydroxylapatite), aluminosilicate clays, metal sulfides, and carbon. We carried out detailed sample analysis of both the standard acid-washing procedure and a modified procedure. Filter plugging by gypsum and metal sulfides appeared to occur because of the acid-washing procedure. Gypsum formation on the filter resulted from significant hydrolysis of sulfamic acid solution at temperatures greater than 130°F. Modification of the acid-washing procedure greatly reduced the amount of gypsum and addition of a surfactant to the acid reduced wash time and mobilized some of the carbon from the filter. With surfactant, acid washing was 95% complete after 40 min.

Investigation of the products of carbothermal reduction of yttrium oxide by the hydrolysis method

1984 ◽  
Vol 49 (4) ◽  
pp. 936-943 ◽  
Author(s):  
Bohumil Hájek ◽  
Pavel Karen ◽  
Vlastimil Brožek
Keyword(s):  
Yttrium Oxide ◽  
Carbothermal Reduction ◽  
Stoichiometric Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrolysis Method ◽  
Sample Decomposition ◽  
Products Of Reaction ◽  
Hydrolysis Of ◽  
Lower Carbon

For the investigation of the products of reaction of yttrium oxide with carbon mixed in various proportions, the chemical and X-ray diffraction methods of analysis were combined with the gas chromatographic analysis of the mixture of hydrocarbons and hydrogen formed on the sample decomposition with water. The carboreduction of Y2O3 was examined at relatively low temperatures, convenient for obtaining the reaction intermediates in higher yields. At 1 600 °C and pressures of 10-3 Pa the reduction of a mixture of Y2O3 with carbon in a stoichiometric ratio of 1 : 7 yields YC2 in equilibrium with 20% of Y2OC phase. At lower carbon contents (down to the Y2O3 : C ratio of 1 : 2) tha fraction of the Y2OC phase increases up to approximately 30%. In addition to Y2O3, the reaction mixture contains also Y2C, Y2OC and a phase giving propyne on hydrolysis. The presence of traces of C3 hydrocarbons and small amounts of methane in the product of hydrolysis of the carbide sample prepared by the carbothermal reduction of the oxide can be explained in terms of the occurrence of the Y15C19 phase, probably substituted in part by oxygen, and of the Y2OC phase. The results are compared with those obtained previously for the Sc2O3 + C system.

VHCF damage in duplex stainless steel revealed by microbeam energy-dispersive X-ray Laue diffraction

2021 ◽  
pp. 106358
Author(s):  
Ali Abboud ◽  
Ali AlHassan ◽  
Benjamin Dönges ◽  
Jean Sebastian Micha ◽  
Robert Hartmann ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Energy Dispersive ◽  
Laue Diffraction ◽  
X Ray

scholarly journals A new synthetic route for the preparation of [Os3(CO)10(μ-OH)(μ-H)] and its reaction with bis(diphenylphosphino)methane (dppm): syntheses and X-ray structures of two isomers of [Os3(CO)8(μ-OH)(μ-H)(μ-dppm)] and [Os3(CO)7(μ3-CO)(μ3-O)(μ-dppm)]

RSC Advances ◽  
2020 ◽  
Vol 10 (73) ◽  
pp. 44699-44711
Author(s):  
Md. Tuhinur R. Joy ◽  
Nikhil C. Bhoumik ◽  
Shishir Ghosh ◽  
Michael G. Richmond ◽  
Shariff E. Kabir
Keyword(s):  
Synthetic Route ◽  
X Ray ◽  
Hydrolysis Of

The cluster [Os3(CO)10(μ-OH)(μ-H)] was obtained in 75% from the hydrolysis of [Os3(CO)10(NCMe)2].

scholarly journals Multifunctional Biodegradable Vascular PLLA Scaffold with Improved X-ray Opacity, Anti-Inflammation, and Re-Endothelization

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1979
Author(s):  
Ho In Lee ◽  
Yun Heo ◽  
Seung-Woon Baek ◽  
Da-Seul Kim ◽  
Duck Hyun Song ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Inflammatory Responses ◽  
Neointimal Hyperplasia ◽  
Film Surface ◽  
High Mechanical Property ◽  
X Ray ◽  
Stent Restenosis ◽  
X Ray Computed ◽  
Hydrolysis Of

Poly(L-lactic acid) (PLLA) has been used as a biodegradable vascular scaffold (BVS) material due to high mechanical property, biodegradability, and biocompatibility. However, acidic byproducts from hydrolysis of PLLA reduce the pH after the surrounding implanted area and cause inflammatory responses. As a result, severe inflammation, thrombosis, and in-stent restenosis can occur after implantation by using BVS. Additionally, polymers such as PLLA could not find on X-ray computed tomography (CT) because of low radiopacity. To this end, here, we fabricated PLLA films as the surface of BVS and divided PLLA films into two coating layers. At the first layer, PLLA film was coated by 2,3,5-triiodobenzoic acid (TIBA) and magnesium hydroxide (MH) with poly(D,L-lactic acid) (PDLLA) for radiopaque and neutralization of acidic environment, respectively. The second layer of coated PLLA films is composed of polydopamine (PDA) and then cystamine (Cys) for the generation of nitric oxide (NO) release, which is needed for suppression of smooth muscle cells (SMCs) and proliferation of endothelial cells (ECs). The characterization of the film surface was conducted via various analyses. Through the surface modification of PLLA films, they have multifunctional abilities to overcome problems of BVS effectively such as X-ray penetrability, inflammation, thrombosis, and neointimal hyperplasia. These results suggest that the modification of biodegradable PLLA using TIBA, MH, PDA, and Cys will have important potential in implant applications.

scholarly journals Leaching of Chalcopyrite under Bacteria–Mineral Contact/Noncontact Leaching Model

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 230
Author(s):  
Pengcheng Ma ◽  
Hongying Yang ◽  
Zuochun Luan ◽  
Qifei Sun ◽  
Auwalu Ali ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Surface Passivation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Leaching Process ◽  
Copper Leaching ◽  
Hydrolysis Of ◽  
Leaching Efficiency ◽  
Leaching Models ◽  
Scanning Electron

Bacteria–mineral contact and noncontact leaching models coexist in the bioleaching process. In the present paper, dialysis bags were used to study the bioleaching process by separating the bacteria from the mineral, and the reasons for chalcopyrite surface passivation were discussed. The results show that the copper leaching efficiency of the bacteria–mineral contact model was higher than that of the bacteria–mineral noncontact model. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) were used to discover that the leaching process led to the formation of a sulfur film to inhibit the diffusion of reactive ions. In addition, the deposited jarosite on chalcopyrite surface was crystallized by the hydrolysis of the excess Fe3+ ions. The depositions passivated the chalcopyrite leaching process. The crystallized jarosite in the bacteria EPS layer belonged to bacteria–mineral contact leaching system, while that in the sulfur films belonged to the bacteria–mineral noncontact system.

Preparation and structural analysis of (±)-threo-ritalinic acid

2013 ◽  
Vol 69 (11) ◽  
pp. 1225-1228 ◽  
Author(s):  
Sara Wyss ◽  
Irmgard A. Werner ◽  
W. Bernd Schweizer ◽  
Simon M. Ametamey ◽  
Selena Milicevic Sephton
Keyword(s):  
Methyl Ester ◽  
Free Acid ◽  
Nmr Analysis ◽  
Intermolecular Hydrogen Bonds ◽  
X Ray ◽  
X Ray Crystallography ◽  
Ph Values ◽  
Ritalinic Acid ◽  
Methyl Phenidate ◽  
Hydrolysis Of

Hydrolysis of the methyl ester (±)-threo-methyl phenidate afforded the free acid in 40% yield,viz.(±)-threo-ritalinic acid, C13H17NO2. Hydrolysis and subsequent crystallization were accomplished at pH values between 5 and 7 to yield colourless prisms which were analysed by X-ray crystallography. Crystals of (±)-threo-ritalinic acid belong to theP21/nspace group and form intermolecular hydrogen bonds. An antiperiplanar disposition of the H atoms of the (HOOC—)CH—CHpygroup (py is pyridine) was found in both the solid (diffraction analysis) and solution state (NMR analysis). It was also determined that (±)-threo-ritalinic acid conforms to the minimization of negativegauche+–gauche−interactions.

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