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PubMed1991

[A study of crystallization on urolithiasis in vitro].

The formation, growth and aggregation of calcium oxalate crystals were evaluated with a Coulter counter. CG-120 and sodium pentosan polysulfate (SPP) has inhibitory activity on calcium oxalate crystal formation, growth and aggregation in the seeded crystal system and whole urine system. In continuous crystallizer system, they inhibit the nucleation rate. A new system of observing the crystal formation and growth of fragmented stones after extracorporeal shock wave lithotripsy has been developed. CG-120 has an inhibitory effect on their growth. The deposition of calcium oxalate crystals in the rat kidney was induced, and the, the volume and number of crystals were estimated using a Coulter counter. SPP has an inhibitory effect on calcium oxalate crystal growth in vivo.

Animals↗
PubMed1991

Effects of pyrophosphatase on dissolution of calcium pyrophosphate dihydrate crystals.

Understanding the dissolution mechanisms involved in calcium pyrophosphate dihydrate (CPPD) crystals may prove important for the development of therapy for CPPD arthropathy. We demonstrate that yeast pyrophosphatase effectively dissolved CPPD crystals in solutions. Maximum enzymatic dissolution of CPPD crystals was achieved at neutral pH and when the enzyme had access to the crystal surface. The enzymatic dissolution of CPPD crystals was highly dependent on ambient [Mg++] and [Ca++]. The stimulating effects of Mg++ on crystal dissolution in the presence of the enzyme is due to stimulation of pyrophosphatase activity and to enhanced direct release of pyrophosphate ions from the crystal surface. The inhibiting effect of Ca++ on crystal dissolution by the enzyme is mainly due to the suppression of pyrophosphatase activity.

Calcium↗
PubMed1991

Systematic use of the incomplete factorial approach in the design of protein crystallization experiments.

We have used the Incomplete Factorial Approach (Carter, C. W., and Carter, C. W., Jr. (1979) J. Biol. Chem. 254, 12219-12223) in conjunction with the program Cristal (Roussel, A., Serre, L., Frey M., and Fontecilla-Camps, J. (1990) J. Crystal Growth 106, 405-409) to crystallize six different proteins. We were able to obtain crystals and to identify the critical factors for crystallization for each of these six proteins. In some of the cases, we succeeded on the first try while using only minute amounts of protein. This study proves that the Incomplete Factorial Approach is a powerful tool in identifying the factors that need to be varied to achieve crystallization. Single crystals of adequate size were obtained for all the proteins reported here, although some did not diffract well enough to be studied by x-ray diffraction methods; the asymmetric units of these latter crystals contain a large metric units of these latter crystals contain a large number of molecules, which is most likely due to the presence of significant amounts of carbohydrate in the proteins.

Animals↗
PubMed1990

The effects of serum and human albumin on calcium hydroxyapatite crystal growth.

The effects of potential serum inhibitors upon the growth of calcium hydroxyapatite (HAP) crystals were studied in vivo using a pH-stat system. Whole serum caused a marked decrease in crystal growth in a dose-dependent manner. At a protein concentration of 13 micrograms/ml, whole serum reduced the initial rate of crystal growth from 84 mumol of KOH/h to 48 mumol of KOH/h. Serum components were separated by ultrafiltration (10,000 Da cut-off). The high-molecular-mass fraction containing serum proteins gave an initial rate of crystal growth of 48 mumol of KOH/h compared with 64 mumol of KOH/h given by the low-molecular-mass components. Thus, two-thirds of the inhibitory activity was associated with proteins and other serum macromolecules, whilst the remainder of the activity was associated with the low-molecular-mass components. Albumin-depleted serum showed an initial rate of crystal growth of 59 mumol of KOH/h, whilst albumin purified by affinity chromatography gave an initial rate of crystal growth of 56 mumol of KOH/h at the same protein concentration. Albumin, therefore, not only accounts for half of the protein concentration in serum, but also contributes half of the inhibitory activity of the high-molecular-mass fraction. Heat denaturation of albumin dramatically enhanced the inhibition of HAP seeded growth with the initial rate of crystal growth falling to 27 mumol of KOH/h after treatment compared with 62 mumol of KOH/h before denaturation. Isoelectric focusing indicated that the tertiary and secondary structure, and hence the distribution of surface charge of albumin, are altered by heat denaturation. Gels showed a mixture of species with isoelectric points ranging from 6.0 to 5.0 compared with the native protein value of 4.7. These data suggest that adsorption of serum proteins to the growing HAP crystals is one mechanism of growth inhibition. It is also clear that the most abundant serum protein, albumin, is an important mediator of this process.

Blood↗
PubMed1988

The inhibition of hemoglobin C crystallization by hemoglobin F.

We have reported that circulating CC erythrocytes containing HbO2 C crystals exhibit little or no Hb F suggesting that Hb F may inhibit the crystallization of Hb C. We report now that Hb F inhibits in vitro crystallization of HbO2 and HbCO C when compared to the effect of Hb A in a wide range of mixture proportions. For example, while HbCO C solutions form tetragonal C crystals within 25 min, no crystals form within 2 h with 30% Hb F, whereas 550 crystals/mm3 form with 30% Hb A. Furthermore, an increase in the percent of Hb A is correlated with a greater number of orthorhombic crystal formation rather than the tetragonal morphology observed with 100% Hb C. We also report that Hb A2 (containing delta chains that exhibit 10 sequence differences with beta chains) and Hb Lepore Boston-Washington (a fusion mutant of delta and beta chains that contains only six of these differences) both inhibit Hb C crystallization. By comparing the sequences of the three inhibitory hemoglobins, we conclude that position Gln-87 in the gamma chains is, at least partially, the cause of the inhibitory effect of Hb F on the crystallization of Hb C.

Amino Acid Sequence↗
PubMed1989

High resolution electron microscopy of enamel crystals in cases of human dental fluorosis.

Surface enamel from human subjects with dental fluorosis was studied by means of high-resolution transmission electron microscopy. Immediately below the relatively highly mineralized outermost surface enamel layer was an extensive hypomineralized area. The highly mineralized layer was composed of many large elongated hexagonal crystals and extremely small hexagonal crystals. Frequently the small crystals were attached to the periphery of the large crystals. In the hypomineralized area, large crystals were sparsely arranged; and a few small crystals were seen. Some large crystals showed either perforated centers or defects on their peripheries. These findings suggest that the hypomineralized area undergoes caries-like changes in terms of crystal dissolution and that the highly mineralized surface layer is either formed or modified by remineralization.

Adult↗
PubMed1985

Crystallization of the Ca2+-ATPase of sarcoplasmic reticulum by calcium and lanthanide ions.

Two-dimensional crystalline arrays of Ca2+-ATPase molecules develop in sarcoplasmic reticulum vesicles exposed to Ca2+ or lanthanide ions. The Ca2+- or lanthanide-induced crystals are presumed to represent the E1 conformation of the Ca2+-ATPase, and their crystal form is clearly different from the earlier described E2 crystals induced by Na3VO4 in the presence of ethylene glycol bis(beta aminoethyl ether)-N,N,N',N'-tetraacetic acid (Taylor, K. A., Dux, L., and Martonosi, A. (1984) J. Mol. Biol. 174, 193-204). Analysis of the crystalline arrays by negative staining or freeze-fracture electron microscopy reveals obliquely oriented rows of particles corresponding to individual Ca2+-ATPase molecules. Computer analysis of the negatively stained lanthanide-induced crystalline Ca2+-ATPase arrays shows that the molecules are arranged in a P1 lattice. The pear-shaped profiles of Ca2+-ATPase molecules seen in projection in the density maps are similar to those seen in vanadate-induced crystals. The space group and unit cell dimensions of the E1 crystals are consistent with Ca2+-ATPase monomers as structural units, while the vanadate-induced E2 crystals form by lateral aggregation of chains of Ca2+-ATPase dimers. The transition between the E1 and E2 conformations may involve a shift in the monomer-oligomer equilibrium of the Ca2+-ATPase. The formation of E1 crystals by PrCl3 is promoted by inside negative membrane potential, presumably through stabilization of the E1 conformation of the enzyme. Cleavage of the Ca2+-ATPase by trypsin into two major fragments (A and B) did not interfere with the Ca2+- or the Pr3+-induced crystallization.

Adenosine Triphosphate↗
PubMed1988

[Clinical studies of the recurrence of urolithiasis (4). Crystal formation in urine and stone recurrence].

Relationship between stone formation and crystal formation in urine was studied. Crystals in the sediments of early morning urine in 238 stone formers and the same numbers of non-stone formers were examined by light microscopy. Almost all crystals found in the early morning urine were composed of calcium oxalate both in stone formers and in non-stone formers. The frequency of calcium oxalate crystal formation was slightly higher in stone formers than in non-stone formers, but, no significant difference was noted. On the other hand, the urine containing calcium oxalate crystals of the stone formers had significantly lower specific gravity than that of the non-stone formers. Calcium oxalate crystals in the urine were formed significantly more frequently in the recurrent or bilateral male stone formers than in male unilateral stone formers without previous stone history. Frequency of calcium oxalate crystal formation was not influenced by urinary excretion of calcium, oxalate, uric acid, phosphate and magnesium. These finding led us to the conclusion that it was clinically useful to measure urinary specific gravity in which calcium oxalate crystals were formed in predicting the risk of stone formation.

Calcium Oxalate↗
PubMed1987

Single crystals of hydrogenase from Desulfovibrio vulgaris Miyazaki F.

The hydrogenase solubilized from the particulate fraction from Desulfovibrio vulgaris Miyazaki F (IAM 12604) has been crystallized. Although the solubilized hydrogenase purified by the previous method (Yagi, T., Kimura, K., Daidoji, H., Sakai, F., Tamura, S., and Inokuchi, H. (1976) J. Biochem. (Tokyo) 79,661-671) revealed a single band upon disc electrophoresis, it could not be crystallized. The apparently homogeneous hydrogenase has been separated into three components of similar molecular weights by high performance liquid chromatography on DEAE-Toyopearl. Each hydrogenase component was successfully crystallized by means of the vapor diffusion method with polyethylene glycol or 2-methyl-2,4-pentanediol as a precipitating agent. Seeding procedure is necessary to grow an x-ray grade crystal. Preliminary x-ray experiments reveal that crystals grown from one component are in space group of P2(1)2(1)2(1) with a = 102.1(1), b = 126.8 (3), and c = 66.9(1) A. The unit cell volume of 8.66 X 10(5) A3 suggests that it contains one molecule/asymmetric unit (Vm = 2.43). The crystals grown from another component are in the same space group with a = 99.6(1), b = 126.8(3), c = 66.9(1) A, and the unit cell volume is 8.45 X 10(5) A3 (Vm = 2.37). The crystals diffract more than 2.5 A and are suitable for complete crystal analysis. Up to 4 A resolution native data have been collected on a diffractometer.

Chromatography, High Pressure Liquid↗
PubMed1984

Crystallization of succinyl-CoA synthetase from Escherichia coli.

Well formed, tetragonal prisms of succinyl-CoA synthetase from Escherichia coli have been crystallized at room temperature from ammonium sulfate and mixtures of sodium and potassium phosphates. A systematic survey of the conditions for crystallization of the enzyme has been carried out. This has shown the addition of a small amount of an organic solvent (acetone, 2-methyl-2,4-pentanediol, tert-butyl alcohol, or tertamyl alcohol) to the phosphate media and of CoA to the sulfate media to be beneficial in producing large, single crystals suitable for analysis by x-ray diffraction methods. Preliminary examination of precession photographs reveals that the crystals from phosphate media have a unit cell of symmetry P4222 with dimensions a = b = 94 A and c = 248 A. Evidence suggests that there may be only half of the (alpha beta)2 tetramer/asymmetric unit in these crystals. The crystals from ammonium sulfate media have unit cell dimensions of a = b = 99 A and c = 399 A, a space group of P4122 (P4322), and one tetramer/asymmetric unit. They diffract to a resolution of 3.4 A. Both crystal types have large solvent contents of about 65% of the unit cell volumes. A parameter called "quality index" is introduced to facilitate comparison of crystals grown under a variety of conditions with respect to their quality of x-ray diffraction.

Coenzyme A↗
PubMed1993

Intracisternal crystals in pancreatic acinar cells: failure in the distinct aggregation of secretory proteins.

Mechanisms leading to the formation of crystalline inclusions in the cisternal space of the rough endoplasmic reticulum are poorly understood. This phenomenon was investigated in pancreatic acinar cells using two different experimental models: 1) Intraperitoneal injection of DL-p-chlorophenylalanine methyl ester, and 2) culture of isolated acinar cells within the Matrigel basement membrane in the presence of 2% dimethyl sulfoxide. Features and composition of induced crystals were analyzed by protein A-gold and lectin-gold cytochemistry, electron microscope autoradiography, electron energy loss spectroscopic imaging and energy dispersive X-ray analysis. Crystal formation occurred in ribosome partially free rough endoplasmic reticulum (RER) regions and was similar in both experimental protocols. The protein A-gold revealed the presence of nine major pancreatic enzymes in the crystals. However, the labeling intensities varied among enzymes with higher concentrations of amylase than chymotrypsinogen when compared to the secretory granules. Concanavalin A and Helix pomatia labelings were weak over the crystals and did not correspond to those of RER or secretory granules. Sulfur contents in crystals were lower than phosphorus and their ratio was opposite to the one found in secretory granules. Electron microscope autoradiography demonstrated incorporation of radiolabeled leucine and presence of newly synthesized proteins in the crystals. Furthermore, cells containing both crystals and secretory granules displayed silver grains in most of the cellular compartments involved in secretion. Thus, failure in the normal concentration and sorting process of secretory proteins leading to crystal formation includes changes in protein glycosylation and decrease of disulfide bond formation while retaining secretory capabilities.

Amylases↗
PubMed1995

[The solubility of calcium pyrophosphate dihydrate crystals].

The solubility of calcium pyrophosphate dihydrate crystals (CPPD crystals), which cause pseudogout, was studied in vitro and vivo. The in vitro experiment using 0.1 M tris buffer and 0.2 M glycine buffer indicated that changes in pH and pyrophosphatase activity played a major role in the solubility of CPPD crystals. An experiment using the synovial fluid from patients with pseudogout, rheumatoid arthritis, and from those with osteoarthritis suggested that changes in the synovial fluid pH due to inflammation affected the solubility of these crystals. In addition, an experiment using the air pouch in rat showed that inflammation due to the CPPD crystals was maximum at about 9 hours after CPPD injection, and that inflammatory cells appearing at this time then had a major influence on the crystals' solubility. From these results, it appeared that CPPD crystals released into the joint cavity were mostly dissolved by inflammatory cells, but that crystal dissolution was also affected by changes in the synovial fluid itself, particularly by a change in pH.

Animals↗
PubMed1994

Induction of rules for biological macromolecule crystallization.

X-ray crystallography is the method of choice for determining the 3-D structure of large macromolecules at a high enough resolution. The rate limiting step in structure determination is the crystallization itself. It takes anywhere between a few weeks to several years to obtain macromolecular crystals that yield good diffraction patterns. The theory of forces that promote and maintain crystal growth is preliminary, and crystallographers systematically search a large parameter space of experimental settings to grow good crystals. There is a wealth of experimental data on crystal growth most of which is in paper laboratory notebooks. Some of the data has been gathered in electronic form, e.g., the Biological Macromolecular Crystallization Database (BMCD) which is a repository of successful experimental conditions for growing over 800 different macromolecules (Gilliland 1987). Crystallographers are in need of computational tools to gather and analyze past data to design new crystal growth trails. We are building the Crystallographer's Assistant (CA) to help crystallographers record and maintain experimental context in electronic form, offer suggestions on experimental conditions that are likely to be successful, and provide explanations for failed experiments. As an initial step in this project, we have applied RL, an inductive learning program, to the BMCD. In this paper we report initial experiments and findings in applying RL to the BMCD. From the point of view of crystallography, we have discovered possibly significant new empirical relationships in crystal growth. From the point of view of machine learning, our work suggests refinements of existing methods for incorporating detailed domain knowledge into inductive analysis techniques.

Animals↗
PubMed1993

[Alizarin red S staining of calcium compound crystals in synovial fluid].

In order to study the clinical value of alizarin red S staining of calcium compound crystals in synovial fluid, the optimum conditions for staining and the detectable threshold of the crystals were examined. The staining of crystals was mainly affected by the concentration of the dye and pH of the solution. The best results were obtained with an alizarin red S concentration of 1.5-3.0% for hydroxyapatite (HA) and 2.0-3.0% for calcium pyrophosphate dihydrate (CPPD) crystal. The optimal pH of the solution was 4.0-6.0 for HA and 4.0-5.5 for CPPD crystal. For the detection of crystals phagocytosed by synovial fluid leukocytes, staining was enhanced by the addition of chloral hydrate to the dye solution which increased the permeability of the cell membrane. The detectable threshold levels of HA and CPPD crystal in synovial fluid by alizarin red S staining were 0.1 micrograms/ml and 0.5 micrograms/ml, respectively. These results suggest that alizarin red S staining is suitable for screening calcium compound crystals in synovial fluid, because it is more sensitive than other methods, such as polarized microscopy and X-ray diffraction. Alizarin red S staining was performed on 148 synovial fluids from patients with various joint diseases. The staining was positive in 100% of synovial fluids from patients with CPPD deposition disease, in 54% of fluids with osteoarthritis, and in 39% of fluids with rheumatoid arthritis. In osteoarthritis, the increase in the proportion of positive cases was found to be in accordance with the radiological grading of the joints.

Anthraquinones↗
PubMed1994

Two crystal structures of the B1 immunoglobulin-binding domain of streptococcal protein G and comparison with NMR.

The structure of the 56-residue B1 immunoglobulin-binding domain from streptococcal protein G has been determined in two different crystal forms. The crystal structures were deduced by molecular replacement, based on the structure of the B2 domain (Brookhaven accession code 1PGX). Final R values are 0.174 and 0.198 for orthorhombic and trigonal forms, for diffraction data from 6.0 to 2.07 A and from 6 to 1.92 A, respectively. The orthorhombic crystals have an unusually high packing density for protein crystals, with Vm = 1.66 and a solvent content of 26%. The protein structure is found to be very similar (rms deviation 0.25 A for 56 C alpha's) in the two crystal forms, with an efficiently packed hydrophobic core between a four-stranded beta-sheet and a four-turn alpha-helix. The B1 domain has the same fold and general structure as the B2 domain (rms deviations 0.36 and 0.39 A), despite the six residue differences between them. The crystallographic models differ from NMR-derived models in several local regions, primarily in the loop involving residues 46-51; other significant variations are observed in the helix and in the structure of bound water. The primary crystal contact is the same in both crystal forms, involving both sheet edges to form extended beta-sheets throughout the crystals.

Amino Acid Sequence↗
PubMed1995

Chemical composition of Schiff's reagent crystals.

Crystals were prepared by adding 0.04 M sulfuric acid to a Schiff's reagent made with 2.5 g pararosaniline (PR) chloride dissolved in a saturated SO2 solution. Elemental analysis of the crystals gave the composition C19H21N3S2O7.4H2O which corresponds to the sulfate of pararosanilinesulfonic acid (PRSA) tetrahydrate. The moisture content was ca. 5%. A reagent reconstituted by dissolving 0.2 grams of crystals in HCl 0.1 N contains ca. 3.5 x 10(-3) M or 0.11% PR. A solution prepared with 2.5 g PR in 100 ml O.1 N HCl plus 0.04 M M K2S2O5 gave only a few crystals after 0.04 M sulfuric acid was added. The PR content, determined colorimetrically, was 0.25% compared with 1.35% in saturated SO2. The per cent dye loss during charcoal purification was also higher. The low concentration of PR, caused both by the lower solubility and by the larger loss during charcoal purification explains the poor yield of crystals of a reagent prepared in HCl/K2S2O5, compared to a reagent prepared in saturated SO2. After crystallization is complete, the crystals are in equilibrium with a concentration of 0.2% of PR in the supernatant: when the initial concentration is close to this value crystallization is negligible or completely fails.

Coloring Agents↗
PubMed1997

The involvement of phosphatidylinositol 3-kinase in crystal induced human neutrophil activation.

OBJECTIVE: We investigated whether phosphatidylinositol (PI) 3-kinase is involved in the signal transduction pathway leading to neutrophil activation by inflammatory microcrystals. METHODS: Neutrophil chemiluminescence and degranulation responses to opsonized crystals were measured in the presence of selective inhibitors known to inhibit PI 3-kinase activity in neutrophils. RESULTS: Wortmannin and LY 294002, 2 selective inhibitors of PI 3-kinase, were shown to inhibit neutrophil activation induced by plasma opsonized crystals of calcium pyrophosphate dihydrate (CPPD) [both monoclinic (M) and triclinic (T) forms] and monosodium urate monohydrate (MSUM). IC50 for wortmannin or LY 294002 inhibition of crystal induced respiratory burst (measured by chemiluminescence) was about 3 nM and 0.3 microM, respectively, proving the pivotal role of PI 3-kinase in neutrophil respiratory burst activation by all 3 crystals. Degranulation responses of neutrophils to CPPD(M) and CPPD(T) crystals were also inhibited by about 50% by wortmannin in the 10 to 20 nM concentration range, supporting the direct involvement of PI 3-kinase in signal transduction pathways leading to crystal induced neutrophil degranulation. All 3 crystals induced the activation of PI 3-kinase in neutrophils as measured by the increased PI 3-kinase activity associated with immunoprecipitated tyrosine phosphorylated proteins from 1 min crystal-neutrophil incubations. Neutrophils pretreated with wortmannin at 10 nM showed sub-basal levels of PI 3-kinase activity at all time points measured. CONCLUSION: PI 3-kinase plays a central role in the signal transduction pathways leading to respiratory burst and degranulation responses in neutrophils activated by inflammatory microcrystals.

Androstadienes↗
PubMed1998

[Spherical crystallization in pharmaceutical technology].

Physical properties of crystals, such as size, crystal size distribution and morphology, may predetermine the usefulness of crystalline materials in many pharmaceutical application. The above properties can be regulated with the crystallization process. The spherical crystals are suitable for direct tablet-making because of their better flowability and compressibility properties. These crystals can be used in the filling of the capsule. In this work, the spherical crystals such as "single crystal", "poly-crystals" and agglomerates with other excipients are collected from the literature and the experimental results of the authors. A close cooperation between chemists and the pharmaceutical technologists can help for doing steps in this field.

Chemistry, Physical↗