Protein self-assemblies at the micro- and nano-scale are of great interest because of their morphological diversity and good biocompatibility. High-throughput screening of protein self-assembly at different scales and morphologies using protein crystallization screening conditions is an emerging method. When using this method to screen protein self-assembly conditions, some apparently transparent droplets are often observed, in which it is not clear whether self-assembly occurs. We explored the interaction between β-lactoglobulin and the protein crystallization kit Index™ C10 and observed the presence of micro- and nano-scale protein self-assemblies in the transparent droplets. The diverse morphology of the micro- and nano-scale self-assemblies in the transparent droplets formed by mixing different initial concentrations of β-lactoglobulin and Index™ C10 was further investigated by scanning electron microscope. Self-assembly process of fluorescence-labelled β-lactoglobulin was monitored continuously by laser confocal microscope, allowing real-time observation of the liquid-liquid phase separation phenomenon and the morphology of the final self-assemblies. The internal structure of the self-assemblies was gradually ordered over time by in-situ X-ray diffraction. This indicates that the self-assembly phenomenon within transparent droplets, observed in protein self-assembly condition screening experiments, is worthy of further in-depth exploration.
Crystallization ; Lactoglobulins

This study was designed to observe the effects of various concentration of polyacrylic acid containing different concentration of sulfate ion on the crystal formation on the enamel surface. Experimental crystal growth solutions were made of 10/, 20% 30%, and 40% polyacrylic acid(molecnlar weight, 5,000) solutions which containing O.1M, 0.2M, 0.3M, 0.5M, and LOM sulfate ion respectively. The extracted human first bicuspid enamel surface was contacted for 60 seconds with these solutions, washed for 15 seconds, dried, and then the crystal topography on the enamel surface was observed under the scanning electron microscope. The crystal topography were evaluated on the SEM photographs by degree of crystal coverage, crystal length, and consistency of crystal morphology, and conclusions were as the follows. 1. Polyacrylic acid. solution etched slightly the enamel surface, and the difference of etching effect by its concentration was not observed. 2. The effect of concentration of polyacrylic acid on the crystal formation was less, especially that of 20% - 40% polyacrylic? acid was almost not different. 3. Concentration of the sulfate ion was a- determinant factor in precipitating crystals on the enamel. The experimental crystal growth solutions containing 0.1 M sulfate ion did not make crystal formation but those containing over 0.2 M sulfate ion did. 4. The degree of crystal coverage showed a tendency to increase and then decrease according to the concentration of sulfate ion in the 20%-40% polyacrylic acid. The experimental solutions containing 0.5 M sulfate ion showed the peak of degree of crystal coverage. 5. The crystal length showed a tendency to decrease by increment of sulfate ion in the polyacrylic acid solution. 6. There was a tendency to increase the frequency of random arragement of short crystals when increasing the concentration of sulfate ion in the polyacrylic acid solution. The lower concentration of sulfate ion in the polyacrylic acid solutions tended to make spherulitic arrangement of crystals, the higher concentration of sulfate ion, the more random arrangement of crystals. The experimental solutions containing 0.5M sulfate ion showed more spherulitic arrangement than random arrangement of crystals. 7. The best one of these experimental crystal growth solutions was 30% polyacrylic acid solution containing 0.5M sulfate ion.
Bicuspid ; Crystallization ; Dental Enamel ; Humans

OBJECTIVETo prepare Form A and Form B of benazepril hydrochloride and to compare the differences in spectrums, thermodynamics and crystal structure between two polymorphic forms.

METHODSForm A and Form B of benazepril hydrochloride were characterized by Fourier transform infrared spectroscopy (IR), thermal gravimetric analysis (TG), differential scanning calorimetry (DSC), powder x-ray diffraction (PXRD) and single crystal x-ray diffraction (SCXRD).

RESULTSPreparation method, crystal structure and polymorphic stability of Form A and Form B of benazepril hydrochloride were obtained. Based on the analysis of crystal structure of both polymorphs, Form A belonged to monoclone space group P2(1) with a=7.8655(4)Å, b= 11.7700(6)Å, c= 13.5560(7)Å, β= 102.9470(10)°, V=1223.07 (11)Å(3) and Z=2, while Form B belonged to orthorhombic space group P212121, with a=7.9353(8)Å, b=11.6654(11)Å, c=26.6453(16)Å, V=2466.5(4)Å(3) and Z=4. From the DSC and XRD results, Form B of benazepril hydrochloride could be transformed into Form A after heating treatment.

CONCLUSIONForm A and Form B of benazepril hydrochloride are both anhydrous and displayed different polymorphs due to different molecular configuration. Furthermore, Form A exhibits more stable than Form B at high temperatures.

The aim of this vitro-study is to evaluate the effects of fluoride on remineralization of artificial dentine caries. 10 sound permanent premolars, which were extracted for orthodontic reason within 1 week, were used for this study. Artificial dentine caries was created by using a partially saturated buffer solution for 2 days with grounded thin specimens and fractured whole-body specimens. Remineralization solutions with three different fluoride concentration (1 ppm, 2 ppm and 4 ppm) were used on demineralized-specimens for 7 days. Polarizing microscope and scanning electron microscope were used for the evaluation of the mineral distribution profile and morphology of crystallites of hydroxyapatite. The results were as follows : 1. When treated with the fluoride solutions, the demineralized dentine specimens showed remineralization of the upper part and demineralization of the lower part of the lesion body simultaneously. 2. As the concentration of fluoride increased, the mineral precipitation in the caries dentine increased. The mineral precipitation mainly occurred in the surface layer in 1 and 2 ppm-specimens and in the whole lesion body in 4 ppm-specimens. 3. When treated with the fluoride solution, the hydroxyapatite crystals grew. This crystal growth was even observed in the lower part of the lesion body which had shown the loss of mineral.
Bicuspid ; Crystallization ; Dentin ; Durapatite ; Electrons ; Fluorides

In order to develop tinted infiltration glass and its colorants, which can make the ceramic have good spectrum transmittance, color space, color stability and be suitable for clinical use, we selected the best prescription and confirm the ingredient and content of the colorants. Molten glass was prepared in Al2O3 crucible by heating the components to 1420 degrees C for 2 hours. The refractive index and thermal stability of the glass were investigated. The refractive index of the MIC infiltration glass was 1.5969(587.6 nm, nd). It was close to the index of aluminous matrix 1.759(546.07 nm, ne), which increased the spectrum transmittance of MIC. The thermal expansion coefficient of the glass was 7.565 microns/m/degree C, which was compatible with the thermal expansion coefficient of aluminous matrix(8.214 microns/m/degree C). This study proved that the tinted infiltration glass has good color stability, spectrum transmittance, and thermal expansion properties.
Aluminum Silicates ; Coloring Agents ; Crystallization ; Dental Porcelain ; Elasticity ; Glass ; Hardness

Kinesin is a motor protein that uses the energy from ATP hydrolysis to move along the microtubule system. To investigate how the chemical energy stored in ATP is converted to mechanical movement, the corresponding N-terminal region of rat brain kinesin was expressed in BL21-Codon Plus (DE3)-RP competent cells. After SP-cation exchange chromatography and size exclusion chromatography, the protein yield reached 10 mg/L culture with the purity above 95%. The purified protein had ATPase activity and specifically reacted with the kinesin antibody in the Western blotting analysis. The purified kinesin was crystallized under the following condition: 1.7 mol/L (NH4)2SO4, 500 mmol/L NaCl, 20% glycerol. The kinesin crystal can diffract up to 2.0 angstroms resolution.
Animals ; Brain ; enzymology ; Crystallization ; Hydrolysis ; Kinesin ; chemistry ; isolation & purification ; Rats

Crystallization has been widely applied in pharmaceutical formulations as an effective approach to improve the stability and efficacy of small agents. However protein crystals are suffered from limitation in the drug delivery system due to their complex crystallization behaviors. With development of crystallization technologies and their industrial application, protein crystals are receiving more and more attentions as a novel delivery system for biomacromolecules. Crystals with thermodynamic stable structure can improve the physical and chemical stability of protein drugs and present a sustained release behavior. On the basis of pertinent literatures, this review introduces the recent research situation and development process of protein crystals as drug delivery system. Moreover, the crystallization process of proteins, as well as the preparation and potential application are discussed systematically.
Crystallization ; Drug Delivery Systems ; Pharmaceutical Preparations ; administration & dosage ; Proteins ; chemistry

Determination of protein 3-dimensional structure offers very important information in biology researches, especially for understanding protein functions and redundant drug design. The X-ray crystallography is still the main technique for protein structure determination. Obtaining protein crystals is an essential procedure after protein purification in this technique. However, there is only 42% of soluble purified proteins yield crystals by statistics. Experimental verification of protein crystallizability is relatively expensive and time-consuming. Thus it is desired to predict the protein crystallizability by a computational method before starting the experiment. In this paper, combined with our own efforts, some successful in silico methods to predict the protein crystallizability are reviewed.
Crystallization ; methods ; Crystallography, X-Ray ; Protein Structure, Tertiary ; Proteins ; chemistry

OBJECTIVETo research the influence of K(2)O composition in the raw material on leucite microcrystallization and to study the effect of leucite content on compressive strength of the dental glass ceramics reinforced by leucite microcrystallization.

METHODSThe raw materials with different K(2)O content were treated by a decided thermal treatment system. The products were analyzed by polaring microscope and X-ray diffractometer, and their compressive strength was also tested.

RESULTSThe microstructure of products from high K(2)O component was remarkably good, at microcrystal size of 0.8 micro m and the compressive strength was 206.6 MPa. A positive correlation was found between leucite volume and the compressive strength when leucite volume was less than 50% (Vol%).

CONCLUSIONSThe component of K(2)O has a great effect on the microstructure and the properties of the leucite-microcrystal-reinforced dental glass ceramics and the content of leucite microcrystals has a notable influence on the compressive strength of the dental glass ceramics.

Urinary citric acid reduces urinary saturation of calcium oxalate and phosphate salts by forming complexes with calcium and retards crystallization of stone forming salts. Hypocitraturia, important factor in stone formation, has been 19-63% of stone patients in various reports. We measured the 24 hour excretion of citric acid. calcium and calcium/citric acid ratio in 100 renal stone patients and 30 healthy controls. The results were as follows: 1. The 24-hour urinary excretion of citric acid was lower in stone patients than in controls, but statistically insignificant (P>0.05). 2. The 24-trour urinary excretion of calcium was higher in stone patients significantly than in Controls (P<0.05). 3. In stone patients, hypocitraturia showed in 19 patients (19%), hypercalciuria in 22 patients (22%). 4. The 24-hour urinary excretion of citric acid had positive correlation with 24-hour urinary excretion of calcium in stone patients (P<0.05) 5. Urinary calcium/citric acid ratio was significantly higher in stone patients than in controls (P<0.05). As results, urinary calcium/citric acid ratio was more significant than the amount of citric acid in stone patients, furthermore it seems to be a useful measure for stone formation and recurrence.
Calcium ; Calcium Oxalate ; Citric Acid* ; Crystallization ; Humans ; Hypercalciuria ; Recurrence ; Salts