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The article discusses a research study on the multiwavelength anomalous diffraction (MAD) for macromolecular phasing at low resolution. Methodology of the study included crystallization where crystals were soaked in cryo-protectant solution and the single-crystal data sets were indexed then integrated by XDS technology solutions. Conclusions indicated the advantages of improved multi-crystal anomalous data in single anomalous diffraction (SAD) phasing including the ability of MAD to allow substructure determinations not seen in single-crystal data.

Gallate dioxygenase (DesB) from Sphingobium sp. SYK-6, which belongs to the type II extradiol dioxygenase family, was purified and crystallized using the hanging-drop vapour-diffusion method. Two crystal forms were obtained. The form I crystal belonged to space group C2, with unit-cell parameters a = 136.2, b = 53.6, c = 55.1 Å, β = 112.8°, and diffracted to 1.6 Å resolution. The form II crystal belonged to space group P21, with unit-cell parameters a = 56.2, b = 64.7, c = 116.1 Å, β = 95.1°, and diffracted to 1.9 Å resolution. A molecular-replacement calculation using LigAB as a search model yielded a satisfactory solution for both crystal forms. [ABSTRACT FROM AUTHOR]

Chiral amino acids without functional groups in their side chains (hydrophobic amino acids) systematically form crystals with two molecules in the asymmetric unit. In contrast, racemates of the same compounds form crystals with Z′ = 1. The present investigation addresses the origin of this important difference between enantiomeric and racemic crystals. Through a series of ab initio calculations on infinite two-dimensional slabs, derived from crystal structures, as well as calculations on full crystal structures it is shown that it is indeed possible to explain the observed behaviour. Addition- ally, the (not unexpected) observation that amino acids usually form racemates in the solid phase rather than undergoing racemic separation upon crystallization is rationalized on the basis of energy calculations. [ABSTRACT FROM AUTHOR]

X-ray crystallography is the most powerful method for determining the three-dimensional structure of biological macromolecules. One of the major obstacles in the process is the production of high-quality crystals for structure determination. All too often, crystals are produced that are of poor quality and are unsuitable for diffraction studies. This review provides a compilation of post-crystallization methods that can convert poorly diffracting crystals into data-quality crystals. Protocols for annealing, dehydration, soaking and cross-linking are outlined and examples of some spectacular changes in crystal quality are provided. The protocols are easily incorporated into the structure-determination pipeline and a practical guide is provided that shows how and when to use the different post-crystallization treatments for improving crystal quality. [ABSTRACT FROM AUTHOR]

The ternary oxide MnReO4, manganese rhenium oxide, has been synthesized under a high pressure of 5.5 GPa at 1473 K and its crystal structure has been determined by single-crystal X-ray diffraction. MnReO4 crystallizes in a wolframite-type structure with average bond lengths of ⟨Re-O⟩ = 1.935 and ⟨Mn-O⟩ = 2.160 Å that are in good agreement with the ionic radii of Re6+ and Mn2+. The magnetic properties of MnReO4 have been studied by SQUID measurements, revealing magnetic ordering below 275 (10) K and a weak ferromagnetic component of the ordered magnetic structure. [ABSTRACT FROM AUTHOR]

We show that the lack of good quality data, normally essential to successful crystal structure analysis, can in part be compensated for by measuring data from several crystals and merging the resulting data sets. The crystal structure of the flame retardant di-p-bromophenyl ether, C12H8Br20, a twofold axially symmetric molecule, has been redetermined and refined from such a merged multi-crystal diffraction data set to an acceptable conventional R factor (R1 = 0.06), a result which could not have been obtained from any one of our single-crystal diffraction data sets used alone in the normal manner. [ABSTRACT FROM AUTHOR]

Erythrocyte NADH-cytochrome b5 reductase reduces methaemoglobin to functional haemoglobin. In order to examine the function of the enzyme, the structure of NADH-cytochrome b5 reductase from human erythrocytes has been determined and refined by X-ray crystallography. At 1.75 Å resolution, the root-mean-square deviations (r.m.s.d.) from standard bond lengths and angles are 0.006 Å and 1.03°, respectively. The molecular structure was compared with those of rat NADH-cytochrome b5 reductase and corn nitrate reductase. The human reductase resembles the rat reductase in overall structure as well as in many side chains. Nevertheless, there is a large main-chain shift from the human reductase to the rat reductase or the corn reductase caused by a single-residue replacement from proline to threonine. A model of the complex between cytochrome b5 and the human reductase has been built and compared with that of the haem-containing domain of the nitrate reductase molecule. The interaction between cytochrome b5 and the human reductase differs from that of the nitrate reductase because of differences in the amino-acid sequences. The structures around 15 mutation sites of the human reductase have been examined for the influence of residue substitutions using the program ROTAMER. Five mutations in the FAD-binding domain seem to be related to cytochrome b5. [ABSTRACT FROM AUTHOR]

Single-stranded DNA-binding (SSB) proteins stabilize single- stranded DNA, which is exposed by separation of the duplex during DNA replication, recombination and repair. The SSB protein from the hyperthermophile Aquifex aeolicus has been overexpressed in Escherichia coli, purified and characterized and crystals of the full- length protein (147 amino acids; Mr 17 131.20) have been grown by vapour diffusion from ammonium sulfate pH 7.5 in both the absence and presence of ssDNA [dT(pT)68]. All crystals diffract to around 2.9 Å resolution and those without bound DNA (native) belong to space group P21, with two tetramers in the asymmetric unit and unit-cell parameters a = 80.97, b 73.40, c = 109.76 Å, β = 95.11°. Crystals containing DNA have unit-cell parameters a = 108.65, b = 108.51, c = 113.24 Å and could belong to three closely related space groups (I222, I212121 or I41) with one tetramer in the asymmetric unit. Electrospray mass spectrometry of the crystals confirmed that the protein was intact. Molecular replacement with a truncated E. coli SSB structure has revealed the position of the molecules in the unit cell and refinement of both native and DNA-bound forms is under way. [ABSTRACT FROM AUTHOR]

The probability formula of direct-method SAD (single- wavelength anomalous diffraction) phasing proposed by Fan & Gu (1985, Acta Cryst. A41, 280-284) contains partial-structure information in the form of a Sim-weighting term. Previously, only the substructure of anomalous scatterers has been included in this term. In the case that the subsequent density modification and model building yields only structure fragments, which do not straightforwardly lead to the complete solution, the partial structure can be fed back into the Sim-weighting term of the probability formula in order to strengthen its phasing power and to benefit the subsequent automatic model building. The procedure has been tested with experimental SAD data from two known proteins with copper and sulfur as the anomalous scatterers. [ABSTRACT FROM AUTHOR]

The probability formula of the direct-method SAD (single-wavelength anomalous diffraction) phasing proposed by Fan & Gu (1985, Acta Cryst. A41, 280-284) contains an error term which is related to the lack-of-closure error. This error term is used as a weighting function in the phase derivation and in the subsequent calculation of electron -density maps. Previously, there has been a constant in the error term that has had to be determined empirically for each particular case. It has been found that improper choice of the constant often leads to failure of the direct-method SAD phasing. The problem is resolved by introducing a modified error term and a method of automatically tuning the associated scaling factor. [ABSTRACT FROM AUTHOR]

A tropical legume, Vigna unguiculata, was explored in order to identify potential allergens among the abundant seed proteins and to attempt their crystallographic study. Salt fractionation of the seed extract followed by chromatographic separation led to the purification of a 25 kDa protein. Gel-filtration chromatography of the 80% ammonium sulfate precipitation fraction led to separation of this protein in pure form, which was subjected to N-terminal sequencing. The N-terminal sequences of internal fragments of this protein showed 85% homology to mung bean seed albumin. This family of proteins is known to be intrinsically allergenic. Rhombic shaped crystals were obtained that diffracted to about 2.1 Å resolution. The crystals belong to space group C2 and have unit-cell parameters a = 124.9, b = 60.1, c = 67.5 Å, β = 111.1°. [ABSTRACT FROM AUTHOR]

Glutamate-5-kinase (05K) catalyzes the first step of proline (and, in mammals, ornithine) biosynthesis. It is a key regulatory point of these routes, since it is the subject of feedback allosteric inhibition by proline or ornithine. The Escherichia coli gene (proB) for G5K was cloned in pET22, overexpressed in E. coli, purified in a few steps in high yield to 95% homogeneity in the highly active proline-inhibitable form and was shown by cross-linking to be a tetramer. It was crystallized by the hanging-drop vapour-diffusion method at 294 K in the presence of ADP, MgCl2 and L-glutamate using 1.6 M MgSO4, 0.1 M KCl in 0.1 M MES pH 6.5 as the crystallization solution. The tetragonal bipyramid-shaped crystals diffracted to 2.5 Å resolution using synchrotron radiation. The crystals belong to space group P41(3)212, with unit-cell parameters a = b = 101.1, c = 178.6 Å, and contain two monomers in the asymmetric unit, with 58% solvent content. [ABSTRACT FROM AUTHOR]

Substructure-solution and phasing procedures using a combination of anomalous scattering and radiation-damage-induced isomorphous differences have been investigated. The tyrosine residues in thaumatin were iodinated with N-iodosuccinimide in the crystalline form as well as prior to crystallization. Several data sets were collected from both forms and used for substructure solution and phasing using various protocols, employing anomalous, isomorphous or both these signals. It was shown that combination of the anomalous and isomorphous signals in the form of the RIPAS (radiation-damage-induced phasing with anomalous scattering) strategy is beneficial for both locating the substructure and subsequent phasing. [ABSTRACT FROM AUTHOR]

The crystal structure of H-(L-Tyr-D-Tyr)4-L-Lys-OH has been determined to 1.3 Å resolution. The D,L-alternating peptide crystallizes in the tetragonal system, space group P43212, with unit-cell parameters a = b = 27.99 (3), c = 78.93 (8) Å. The crystals contain two molecules in the asymmetric unit that form a double-stranded right-handed antiparallel β-helix. The structure has been solved by SIRAS using a crystal soaked in an iodide-containing solution for 1 mm. The programs SHELXD and SHELXE were used to determine the iodide substructure and also the experimental electron-density map. Using the coordinates of known D,L-peptides deposited in the PDB, several attempts were made to solve the structure by molecular-replacement techniques. Although the backbone of the MR model selected shows great similarity and was used to trace the actual peptide structure in the map, it was not possible to obtain the correct solution before the experimental phases became available. The correct fragment orientations are easily determined, but the same does not apply to the translation search. Nevertheless, insights into fragment search and expansion were gained from the tests described in this paper. The correlation coefficient calculated with the resolution shell of data around 2.4 Å, a distance corresponding to most 1-3 interatomic vectors, is a particularly good discriminator of correct orientations in the rotation search of small fragments. [ABSTRACT FROM AUTHOR]

Structural studies of a ternary complex composed of the Yersina pestis virulence factors YopN, SycN and YscB were initially hampered by poor solubility of the individual proteins. Co-expression of all three proteins in Escherichia co/i yielded a well behaved complex, but this sample proved to be recalcitrant to crystallization. As crystallization efforts remained fruitless, even after the proteolysis-guided engineering of a truncated YopN polypeptide, reductive methylation of lysine residues was employed to alter the surface properties of the complex. The methylated complex yielded crystals that diffracted X-rays to a maximal resolution of 1.8 Å. The potential utility of reductive methylation as a remedial strategy for high-throughput structural biology was further underscored by the successful modification of a selenomethionine -substituted sample. [ABSTRACT FROM AUTHOR]

PhzG is a flavin-dependent oxidase that is believed to play a role in phenazine antibiotic synthesis in various bacteria, including Pseudo- monas. Phenazines are chorismic acid derivatives that provide the producing organisms, including the opportunistic pathogen P. aeruginosa, with a competitive growth advantage. Here, the crystal structures of PhzG from both P. aeruginosa and P. fluorescens solved in an unliganded state at 1.9 and 1.8 A resolution, respectively, are described. Although the specific reaction in phenazine biosynthesis catalyzed by PhzG is unknown, the structural data indicates that PhzG is closely related to pyridoxine-5'-phosphate oxidase, the Escherichia coli pdxH gene product, which catalyzes the final step in pyridoxal-5'-phosphate (PLP) biosynthesis. A previous proposal suggested that the physiological substrate of PhzG to be 2,3-dihydro-3-hydroxyanthranilic acid (DHHA), a phenazine precursor produced by the sequential actions of the PhzE and PhzD enzymes on chorismate, and that two DHHA molecules dimerized in another enzyme-catalyzed reaction to yield phenazine-1-carboxylate. However, it was not possible to demonstrate any in vitro activity upon incubation of PhzG and DHHA. Interestingly, analysis of the in vitro activities of PhzG in combination with PhzF suggests that PhzF acts on DHHA and that PhzG then reacts with a non-aromatic tricyclic phenazine precusor to catalyze an oxidation/aromatization reaction that yields phenazine-1-carboxylate. It is proposed that phzG arose by duplication of pdxH and that the subtle differences seen between the structures of PhzG and PdxH correlate with the loss of the ability of PhzG to catalyze PLP formation. Sequence alignments and superimpositions of the active sites of PhzG and PdxH reveal that the residues that form a positively charged pocket around the phosphate of PLP in the PdxH-PLP complex are not conserved in PhzG, consistent with the inability of phosphorylated compounds to serve as substrates for PhzG. [ABSTRACT FROM AUTHOR]

Isopentenyl pyrophosphate (IPP) is a universal building block for the ubiquitous isoprenoids that are essential to all organisms. The enzymes of the non-mevalonate pathway for IPP synthesis, which is unique to many pathogenic bacteria, have recently been explored as targets for antibiotic development. Several crystal structures of 2 C-methyl-D-erythritol- 2,4-cyclophosphate (MECDP) synthase, the fifth of seven enzymes involved in the non-mevalonate pathway for synthesis of IPP, have been reported; however, the composition of metal ions in the active site and the presence of a hydrophobic cavity along the non-crystallographic threefold symmetry axis has varied between the reported structures. Here, the structure of MEDCP from Shewanella oneidensis MR1 (SO3437) was determined to 1.6 Å resolution in the absence of substrate. The presence of a zinc ion in the active-site cleft, tetrahedrally coordinated by two histidine side chains, an aspartic acid side chain and an ambiguous fourth ligand, was confirmed by zinc anomalous diffraction. Based on analysis of anomalous diffraction data and typical metal-to-ligand bond lengths, it was concluded that an octahedral sodium ion was 3.94 Å from the zinc ion. A hydrophobic cavity was observed along the threefold non-crystallographic symmetry axis, filled by a well defined non-protein electron density that could be modeled as farnesyl pyrophosphate (FPP), a downstream product of IPP, suggesting a possible feedback mechanism for enzyme regulation. The high- resolution data clarified the FPP-binding mode compared with previously reported structures. Multiple sequence alignment indicated that the residues critical to the formation of the hydrophobic cavity and for coordinating the pyrophosphate group of FPP are present in the majority of MEDCP synthase enzymes, supporting the idea of a specialized biological function related to FPP binding in a subfamily of MEDCP synthase homologs. [ABSTRACT FROM AUTHOR]

Several stable domains of the phosphoprotein (P) of vesicular stomatitis virus (Indiana) were identified by limited proteolysis of purified recombinant F protein expressed in Escherichia coli. The proteinase-K-resistant domain could he crystallized using ammonium sulfate as a precipitant and ethylene glycol as an additive. The crystals belong to space group P41212 or P43212, with unit-cell parameters a = h = 74.50, c = 156.84 Å. X-ray diffraction data were collected to 2.75 Å resolution at a synchrotron-radiation source. [ABSTRACT FROM AUTHOR]

Escherichia coli argininosuccinate lyase has been crystallized from a highly concentrated sample of purified recombinant α-methylacyl-CoA racemase, in which it occurred as a minor impurity. The structure has been solved using molecular replacement at 2.44 Å resolution. The enzyme is tetrameric, but in this crystal form there is a dimer in the asymmetric unit. The tetramer has four active sites; each active site is constructed from loops of three different subunits. One of these catalytic loops, near residues Ser277 and Ser278, was disordered in previous structures of active lyases, but is very well ordered in this structure in one of the subunits owing to the presence of two phosphate ions in the active-site cavity. The positions of these phosphate ions indicate a plausible mode of binding of the succinate moiety of the substrate in the competent catalytic complex. [ABSTRACT FROM AUTHOR]

Sialidases catalyse the removal of terminal sialic acids from a range of glycoproteins, glycolipids and oligosaccharides. They have been found in bacteria, viruses and parasites, where they play important roles in pathogenesis and/or microbial nutrition, and in mammalian cells, where they modulate cell-surface glycosylation associated with a range of cellular activities. Clostridium perfringens, a causative agent of gas gangrene and peritonitis in humans, possesses three sialidases: nanH, nanI and nanJ, with molecular weights of 42, 77 and 129 kDa, respectively. The two larger enzymes are secreted by the bacterium and are involved in the pathogenesis and nutrition of Clostridium. As part of a study to examine the structures of all three enzymes, crystallization of the 77 kDa nanI isoenzyme was attempted. The expressed full-length protein was found to degrade easily; a stable 50 kDa catalytic domain was therefore subcloned. This domain was overexpressed in Escherichia coli and produced crystals belonging to space group P212121, with unit-cell parameters a = 96.98, h = 69.41, c = 72.69 Å and one monomer per asymmetric unit. The crystals diffract to at least 0.92 Å. A molecular-replacement solution was obtained using the catalytic domain of the sialidase from the leech Macrobdella decora. [ABSTRACT FROM AUTHOR]

One of the key obstacles in the progress of certain aspects of solid-state physics is the determination of the nature of irregularities in the atomic network of matter and their correlation with macroscopic properties. In this work, an original structural result is presented, namely the presence of icosahedral clusters in an Al solid solution, as deduced from the analysis of the total Fourier- space image. This work has led to the belief that these non-crystalline clusters create a fundamental irregularity in the network of a non-ideal solid solution. [ABSTRACT FROM AUTHOR]

The Mycobacterium tuberculosis open reading frame Rv3214, annotated as a cofactor-dependent phosphoglycerate mutase, has been cloned and expressed as an N-terminally His-tagged protein. Tagged, untagged and selenomethionine-labelled forms of Rv3214 (EntD) have been purified using nickel-affinity chromatography and gel filtration. The selenomethionine-labelled crystals diffracted to 2.15 Å resolution and belong to space group P21, with unit-cell parameters a = 44.36, b = 79.03, c = 52.85 Å, β = 109.11°. There are two molecules of molecular weight 21 948 Da per asymmetric unit. [ABSTRACT FROM AUTHOR]

Regucalcin is a novel calcium ion (Ca2+) binding protein that does not contain an EF-hand motif as a Ca2+-binding domain and has been demonstrated to play a multi-functional role in many cell types. Human liver regucalcin, consisting of 299 amino-acid residues, was overexpressed in Escherichia coli, purified and crystallized by the vapour-diffusion method in the presence of polyethylene glycol 4000 as a precipitant. A native crystal diffracted to 2.8 Å with synchrotron radiation and belongs to space group P21, with unit-cell parameters a = 64.87, b = 52.52, c = 86.38 Å, β = 99.86°. Two molecules most probably exist in the asymmetric unit, corresponding to VM 2.2 ų Da-1. Heavy-atom derivative data were collected and the Pb derivative showed one high-occupancy site per molecule. [ABSTRACT FROM AUTHOR]

Crystals of purified heterodimeric sulfite dehydrogenase from Starkeya novella have been grown using vapour diffusion. X-ray diffraction data have been collected from crystals of the native protein at λ = 1.0 Å and close to the iron absorption edge at λ = 1.737 Å. The crystals belong to space group P21212, with unit-cell parameters a = 97.5, b = 92.5, c = 55.9 Å. Native data have been recorded to 1.8 Å resolution and Fe-edge data to 2.5 Å. [ABSTRACT FROM AUTHOR]

The banana lectin from Musa paradisiaca, MW 29.4 kDa, has been isolated, purified and crystallized. The trigonal crystals contain one dimeric molecule in the asymmetric unit. The structure has been solved using molecular replacement to a resolution of 3 A. The structure of the subunit is similar to that of jacalin-like lectins. [ABSTRACT FROM AUTHOR]

Vacuolar sorting receptor (VSR) proteins bind soluble protein ligands in a sequence-specific manner and target them to the lytic vacuole in plant cells. A VSR from Arabidopsis thaliana, AtBP80b, has been successfully purified after heterologous expression in Drosophila S2 cells. The AtBP80b protein (560 amino acids) was crystallized by the hanging-drop method with a PEG 400-based precipitant. Preliminary X-ray diffraction studies of an AtBP80b crystal showed that it belongs to the cubic space group P213 (or P4232) and has unit-cell parameters a = b = c = 145.9 Å. Crystals of the VSR diffract beyond 2.5 Å resolution. [ABSTRACT FROM AUTHOR]

The enzymes of the shikimate pathway are potential targets for the development of new therapies because they are essential for bacteria but absent from mammals. The last step in this pathway is performed by chorismate synthase (CS), which catalyzes the conversion of 5-enolpyruvylshikimate-3-phosphate to chorismate. Optimization of crystallization trials allowed the crystallization of homogeneous recombinant CS from Mycobacterium tuberculosis (MtCS). The crystals of MtCS belong to space group P6422 (or P6222) and diffract to 2.8 Å resolution, with unit-cell parameters a = b = 129.7, c = 156.8 Å. There are two molecules in the asymmetric unit. Molecular-replacement trials were not successful. Heavy-atom derivative screening is in progress. [ABSTRACT FROM AUTHOR]

TraF, a component of the Escherichia coli type IV secretory system, has been crystallized and preliminary X-ray diffraction data have been collected. TraF is a 26 kDa protein encoded by the E. coli F plasmid and is required for conjugative plasmid transfer and the formation of sex pili. The N-terminal domain of TraF has no recognizable sequence features, whereas the C-terminal domain is believed to adopt a thioredoxin fold. However, since the active-site cysteines of thioredoxin-like proteins are not conserved in TraF, its biochemical role remains unclear. TraF crystallizes in space group C2, with unit-cell parameters a = 119.87, b = 34.36, c = 46.21 Å, β = 90.40°, and crystals diffract to 2.3 Å resolution. [ABSTRACT FROM AUTHOR]

Mouse autocrine motility factor (mAMF), a tumour-secreted cytokine that stimulates cell migration in vitro and metastasis in vivo, has been crystallized by the hanging-drop vapour-diffusion method. The crystals belong to the monoclinic space group P21, with unit-cell parameters a = 69.97, b = 115.88, c = 73.27 Å, β = 101.76°. There are two subunits (one dimer) per asymmetric unit. Complexes with four-, five- and six-carbon carbohydrate phosphate inhibitors have also been crystallized. The crystals diffract to at least 1.8 Å resolution and are suitable for X-ray structure analyses at high resolution. [ABSTRACT FROM AUTHOR]

Tryptophanase from Escherichia coli is a pyridoxal phosphate- dependent homotetrametic enzyme with a subunit weight of 52 kDa. It has been crystallized in the apo form by the hanging-drop vapour- diffusion method using polyethylene glycol 400 as a precipitant and magnesium chloride as an additive. The crystals belong to the orthorhombic space group F222, with unit-cell parameters a = 118.4, b = 120.1, c = 171.2 Å. A 97.8% complete data set to 1.9 Å resolution was collected at a rotating-anode source from a single frozen crystal. Packing-density considerations agree with a monomer in the asymmetric unit with a solvent content of 55%. Tryptophanase mutants W330F and Y74F were crystallized under the same conditions and the crystals diffracted to a resolution limit of 1.9 Å. Data sets of wild-type crystals soaked with L-tryptophan or pyridoxal phosphate were collected, as well as of Y74F mutant soaked with both. [ABSTRACT FROM AUTHOR]

Retinoids have demonstrated therapeutic efficacy in the treatment of acute promyelocytic leukaemia and in the chemoprevention of a large number of cancers. As the cellular signalling pathway of retinoids can be transduced by the three retinoic acid receptor (RAR) isotypes α, β and γ, the side effects of these treatments induced efforts to generate isotype-selective ligands. Despite knowledge of the crystal structures of RARα and RARγ ligand-binding domains (LBDs), the rational design of such ligands has been hampered by the absence of RARβ LBD structural data. Here, a strategy used to express a large-scale soluble fraction of the human RARβ LBD suitable for biophysical analysis is reported, as well as a procedure for crystallizing it bound to a synthetic retinoid (TTNPB) with or without a co-activator peptide (SRC-1). Preliminary X-ray analysis revealed that both complexes crystallized in the orthorhombic space group P212121. The unit-cell parameters are a = 47.81, b = 58.52, c = 92.83 Å for the TTNPB-hRARβ LBD crystal and a = 58.14, b = 84.07, c = 102.37 Å when the SRC-1 peptide is also bound. [ABSTRACT FROM AUTHOR]

Chitosanase from Bacillus sp. strain K17 (ChoK) belongs to glycoside hydrolase family 8 and exhibits subclass II specificity. The purified protein is structurally stable over a wide pH range (3-10), but is active in a much narrower pH range (4.5-7.5), with optimal activity around pH 6.0. The protein has been successfully crystallized at two different pH values corresponding to the active and inactive states. The crystals diffract to 1.5 and 2.0 Å resolution, respectively. [ABSTRACT FROM AUTHOR]

Crystals of a 2-Helix fusion-core construct of MHV spike protein (commonly referred to as E2) have been grown at 291 K using PEG 4000 as precipitant. The diffraction pattern of the crystal extends to 2.8 Å resolution at 100 K in-house. Furthermore, a selenomethionine (SeMet) derivative of MHV spike protein fusion core has been overexpressed and purified. The derivative crystals were obtained under similar conditions and three different wavelength data sets were collected to 2.4 Å resolution from a single derivative crystal at BSRF (Beijing Synchrotron Radiation Facility). The crystals have unit-cell parameters a = b = 48.3, c = 199.6 Å, α = β = 90, γ = 120° and belong to space group R3. Assuming the presence of two molecules in the asymmetric unit, the solvent content is calculated to be about 46%. [ABSTRACT FROM AUTHOR]

VCBPs represent a family of proteins with highly diversified immunoglobulin-like variable regions in species thought to lack an adaptive immune system. These proteins are expected to reveal important structural and functional features that could be highly informative in projecting the evolutionary history of the adaptive immune response. Preliminary X-ray diffraction data from amphioxus (Branchiostoma floridae,) VCBP3 crystals were collected to 2.4 Å resolution and reduced to primitive trigonal space groups P31(2)21. Unit-cell parameters are a = b = 58.99, c = 79.21 Å, α = β = 90, γ = 120°. Two distinct crystallization conditions yielded crystals with similar morphologies and these crystals are isomorphous to each other. [ABSTRACT FROM AUTHOR]

Mexicain is a 23.7 kDa papain-like cysteine protease from the tropical plant Jacaratia mexicana. Extracted as a mix of proteases from the latex of the fruit, mexicain is isolated after cation-exchange chromatography as the most abundant product. The purified product inhibited with E-64 was crystallized by sitting-drop vapour diffusion in the presence of ethanolamine. Cryoprotected crystals diffracted X-rays from a home source to 1.98 Å and belong to the monoclinic space group P21, with unit-cell parameters a = 57.36, b = 90.45, c = 80.39 Å, β = 92.64°. The asymmetric unit contains four molecules of mexicain, with a corresponding crystal volume per protein weight (VM) of 2.24 ų Da-1 and a solvent content of 45% by volume. A molecular-replacement model has been determined and refinement is in progress. [ABSTRACT FROM AUTHOR]

A core fragment of the bacterial flagellar hook protein FlgE was overexpressed, purified and crystallized. The crystal diffracted to 1.6 Å resolution using synchrotron X-radiation. The crystal belongs to the orthorhombic crystal system, with space group P21212 and unit-cell parameters a = 128.4, b = 48.8, c = 96.7 Å. SeMet protein was also overexpressed, purified, crystallized and a set of 2.3 Å MAD data was collected. [ABSTRACT FROM AUTHOR]

Horse pancreatic lipase-related proteins PLRP1 and PLRP2 are produced by the pancreas together with pancreatic lipase (PL). Sequence-comparison analyses reveal that the three proteins possess the same two-domain organization: an N-terminal catalytic domain and a C-terminal domain, which in PL is involved in colipase binding. Nevertheless, despite the high level of sequence identity found, they exhibit distinct enzymatic properties. The intrinsic sensitivity of the peptide bond between Ser245 and Thr246 within the flap region of PLRP2 to proteolytic cleavage probably complicates PLRP2 crystallization since, as shown here, this proteolyzed form of PLRP2 is only crystallized after specific detergent stabilization of this region. This has been performed by the hanging-drop vapour-diffusion method at 291 K and exclusively in the presence of N,N-dimethyldecylamine-β-oxide (DDAO). However, most crystals (>95%) are highly twinned and diffract poorly (to ∼7-5 Å resolution). Diffraction-quality trigonal crystals have unit-cell parameters a = b = 128.4, c = 85.8 Å and belong to space group P3221. A 2.9 Å native data set was collected at ESRF on beamline ID14-2 with an Rmerge of 12.7%. Preliminary structural analysis provides a structural basis for the specific roles of DDAO. [ABSTRACT FROM AUTHOR]

Polyamines, such as putrescine, spermidine and spermine, are essential for the regulation of cell proliferation and differentiation in most organisms. Spermidine synthase catalyzes the transfer of the aminopropyl group from decarboxylated S-adenosylmethionine to putrescine in the biosynthesis of spermidine. In this study, spermidine synthase of Helicobacter pylon has been overexpressed in Escherichia coli and purified. Two kinds of spermidine synthase crystals were obtained. One belongs to the monoclinic P21 space group, with unit-cell parameters a = 62.78, b = 58.24, c = 74.28 Å, β = 90.9°, and the other belongs to the orthorhombic C2221 space group, with unit-cell parameters a = 100.43, b = 128.55, c = 143.60 Å. [ABSTRACT FROM AUTHOR]

The catalytic fragment of human 2',3'-cyclic nucleotide 3'-phosphodiesterase (hcNP-CF) has been crystallized by the hanging-drop vapour-diffusion method using polyethylene glycol 300 as the precipitating agent. The crystals belong to the orthorhombic space group P212121, with unit-cell parameters a = 44.39, b = 55.35, c = 78.76 Å. There is one molecule per asymmetric unit. The crystals diffract to at least 1.8 Å resolution using synchrotron radiation and are suitable for X-ray structure analysis at high resolution. [ABSTRACT FROM AUTHOR]

Infestin is a protein from Triatoma infestans (kissing bug) composed of seven Kazal-type domains that is further processed to yield several serine protease inhibitors with varying specificities. Infestins 3 and 4 are the last two domains of the infestin gene and are found in vivo in the insect's anterior midgut. The last domain, infestin 4, has been cloned, expressed and purified. Here, the crystallization of infestin 4 using the sitting-drop vapour-diffusion method with PEG 8000 as precipitant is described. Crystals belong to the orthorhombic space group P212121, with unit-cell parameters a = 25.89, b = 45.64, c = 57.41 Å. X-ray diffraction data were collected to a maximum resolution of 1.8 Å using a synchrotron-radiation source. Initial phases were calculated by molecular replacement using an edited rhodniin molecule as the search model. Structure refinement is in progress. [ABSTRACT FROM AUTHOR]

Chitinase F1 (ChiF1) isolated from the alkaliphilic Nocardiopsis sp. strain F96 is a family 18 chitinase that hydrolyzes chitin, an insoluble β-1,4-linked polymer of N-acetylglucosamine. Crystals of recombinant ChiF1 with molecular weight of 33 000 Da were grown to a suitable size for X-ray structure analysis using 18%(wlv) polyethylene glycol 8000, 200 mM zinc acetate dehydrate and 100 mM sodium cacodylate buffer pH 6.5. Diffraction data were collected at SPring-8 and show that the crystals belong to the trigonal space group P3112 or P3212, with unit-cell parameters a = 56.0, c = 179.5 Å, and diffract X-rays beyond 1.2 Å resolution. Crystallographic analysis was carried out using the multiwavelength anomalous diffraction (MAD) method using zinc as the anomalous scatter. The binding of Zn atoms was clarified from the Bijvoet and dispersive Patterson functions, which gave prominent zinc-zinc self-vectors on the Harker section. [ABSTRACT FROM AUTHOR]

The design of an apparatus based on Bridgman's method, enabling visualization of the growth process and regulation of the crystallization rate, for obtaining single crystals from a melt in a school laboratory is presented. Conditions for obtaining single crystals of several substances are given. [ABSTRACT FROM AUTHOR]

Peroxisomal enzymes are responsible for several primary metabolism pathways, including β-oxidation and lipid biosynthesis. PEX1 and PEX6 are hexameric AAA-type ATPases and both are necessary for the import of more than 50 peroxisomal resident proteins from the cytosol into peroxisomes. In this study, PEX1 N-terminal domain crystals have been prepared. The crystals belong to space group P31 or P32, with unit-cell parameters a = b = 63.5 Å, c = 33.5 Å, and contain one protein molecule per crystallographic asymmetric unit. An intensity data set was collected to a resolution of 2.05 Å. [ABSTRACT FROM AUTHOR]

Pyridoxal 4-dehydrogenase (PLDH; EC L1.107) is the second enzyme in the bacterial degradation pathway I of vitamin B6, which catalyzes the oxidation of pyridoxal to 4-pyridoxolactone using NAD+. PLDH from Microbacterium luteolum, a dimeric protein with a subunit molecular weight of 38 kDa, was crystallized at 277 K in a drop solution comprising 15%(w/v) polyethylene glycol 4000, 0.15 M sodium acetate, 7.5 mM n-octyl-β-D-glucoside and 0.075 M Tris-HCl pH 7.5 by the sitting-drop vapour-diffusion method. The crystals were monoclinic and belonged to space group C2, with unit-cell parameters a = 107.0, h = 56.7, c = 130.2 Å, β = 103.6°. Diffraction data were collected from a single crystal to 2.0 Å. [ABSTRACT FROM AUTHOR]

The author reflects on the origin of this journal based on physical sciences. It states that as the need for publishing crystallization reports arose with developments in the field of biology, this journal took shape. It also mentions about the goal of the periodical which is structural biology communications to the society.

In November 2006, we (Ji-Lin Lu, Da-Shun Zhang, Lin Li and Bei-Ping Liu) published a paper on the crystal structure of 1,4-dihydro-3,6-dipyrazin-2-yl-1,2,4,5-tetra­zine–benzene-1,3-dicarboxylic acid (1/1) [ ]. The synthesis and characterization of the compound, the X-ray data collection, crystal structure solution and refinement were carried out in the laboratory of Professor Miao Du, Tianjin Normal University, People's Republic of China. We obtained this crystallographic information from his student and published the paper without Professor Du's permission. We now retract this paper and offer our sincere apologies to Professor Du. [ABSTRACT FROM AUTHOR]