bluuebunny/crossref_metadata_2025 huggingface dataset:
ANT1, an Aromatic and Neutral Amino Acid Transporter in Arabidopsis
Authors: Chen Lishan , Ortiz-Lopez Adriana , Jung Alan , Bush Daniel R.
Published: July 2002

A new amino acid transporter was identified from the Arabidopsis expressed sequence tag cDNAs by expressing the cDNA in a yeast amino acid transport mutant. Transport analysis of the expressed protein in yeast showed that it transports aromatic and neutral amino acids, as well as arginine. This transporter (ANT1, aromatic and neutral transporter) also transports indole-3-acetic acid and 2,4-dichlorophenoxyacetic acid. The cDNA is 1.6 kb in length with an open reading frame that codes for a protein with 432 amino acids and a calculated molecular mass of 50 kD. Hydropathy analysis showedANT1 is an integral membrane protein with 11 putative membrane-spanning domains. Southern analysis and a BLAST search of the Arabidopsis genome database suggests that ANT1 is part of a small gene family containing at least five members. Phylogenetic comparisons with other known amino acid transporters in plants suggests that ANT1 represents a new class of amino acid transporter. RNA gel-blot analysis showed that this transporter is expressed in all organs with highest abundance in flowers and cauline leaves.
Phenol-Oxidizing Peroxidases Contribute to the Protection of Plants from Ultraviolet Radiation Stress
Authors: Jansen Marcel A.K. , van den Noort Ria E. , Tan M.Y. Adillah , Prinsen Els , Lagrimini L. Mark , Thorneley Roger N.F.
Published: July 2002

We have studied the mechanism of UV protection in two duckweed species (Lemnaceae) by exploiting the UV sensitivity of photosystem II as an in situ sensor for radiation stress. A UV-tolerantSpirodela punctata G.F.W. Meyer ecotype had significantly higher indole-3-acetic acid (IAA) levels than a UV-sensitive ecotype. Parallel work on Lemna gibbamutants suggested that UV tolerance is linked to IAA degradation rather than to levels of free or conjugated IAA. This linkage is consistent with a role for class III phenolic peroxidases, which have been implicated both in the degradation of IAA and the cross-linking of various UV-absorbing phenolics. Biochemical analysis revealed increased activity of a specific peroxidase isozyme in both UV-tolerant duckweed lines. The hypothesis that peroxidases play a role in UV protection was tested in a direct manner using genetically modified tobacco (Nicotiana sylvestris). It was found that increased activity of the anionic peroxidase correlated with increased tolerance to UV radiation as well as decreased levels of free auxin. We conclude that phenol-oxidizing peroxidases concurrently contribute to UV protection as well as the control of leaf and plant architecture.
NAD Malic Enzyme and the Control of Carbohydrate Metabolism in Potato Tubers
Authors: Jenner Helen L. , Winning Brenda M. , Millar A. Harvey , Tomlinson Kim L. , Leaver Christopher J. , Hill Steven A.
Published: July 2002

Potato (Solanum tuberosum) plants were transformed with a cDNA encoding the 59-kD subunit of the potato tuber NAD-dependent malic enzyme (NADME) in the antisense orientation. Measurements of the maximum catalytic activity of NADME in tubers revealed a range of reductions in the activity of this enzyme down to 40% of wild-type activity. There were no detrimental effects on plant growth or tuber yield. Biochemical analyses of developing tubers indicated that a reduction in NADME activity had no detectable effects on flux through the tricarboxylic acid cycle. However, there was an effect on glycolytic metabolism with significant increases in the concentration of 3-phosphoglycerate and phosphoenolpyruvate. These results suggest that alterations in the levels of intermediates toward the end of the glycolytic pathway may allow respiratory flux to continue at wild-type rates despite the reduction in NADME. There was also a statistically significant negative correlation between NADME activity and tuber starch content, with tubers containing reduced NADME having an increased starch content. The effect on plastid metabolism may result from the observed glycolytic perturbations.
Ethylene Induces Antifreeze Activity in Winter Rye Leaves
Authors: Yu Xiao-Ming , Griffith Marilyn , Wiseman Steven B.
Published: July 2002

Antifreeze activity is induced by cold temperatures in winter rye (Secale cereale) leaves. The activity arises from six antifreeze proteins that accumulate in the apoplast of winter rye leaves during cold acclimation. The individual antifreeze proteins are similar to pathogenesis-related proteins, including glucanases, chitinases, and thaumatin-like proteins. The objective of this study was to study the regulation of antifreeze activity in response to ethylene and salicyclic acid, which are known regulators of pathogenesis-related proteins induced by pathogens. Nonacclimated plants treated with salicylic acid accumulated apoplastic proteins with no antifreeze activity. In contrast, when nonacclimated plants were exposed to ethylene, both antifreeze activity and the concentration of apoplastic protein increased in rye leaves. Immunoblotting revealed that six of the seven accumulated apoplastic proteins consisted of two glucanases, two chitinases, and two thaumatin-like proteins. The ethylene-releasing agent ethephon and the ethylene precursor 1-aminocyclopropane-1-carboxylate also induced high levels of antifreeze activity at 20°C, and this effect could be blocked by the ethylene inhibitor AgNO3. When intact rye plants were exposed to 5°C, endogenous ethylene production and antifreeze activity were detected within 12 and 48 h of exposure to cold, respectively. Rye plants exposed to drought produced both ethylene and antifreeze activity within 24 h. We conclude that ethylene is involved in regulating antifreeze activity in winter rye in response to cold and drought.
The Arabidopsis immutans Mutation Affects Plastid Differentiation and the Morphogenesis of White and Green Sectors in Variegated Plants
Authors: Aluru Maneesha R. , Bae Hanhong , Wu Dongying , Rodermel Steven R.
Published: July 2002

The immutans (im) variegation mutant of Arabidopsis has green and white leaf sectors due to the action of a nuclear recessive gene, IMMUTANS (IM). This gene encodes the IM protein, which is a chloroplast homolog of the mitochondrial alternative oxidase. Because the white sectors ofim accumulate the noncolored carotenoid, phytoene, IM likely serves as a redox component in phytoene desaturation. In this paper, we show that IM has a global impact on plant growth and development and is required for the differentiation of multiple plastid types, including chloroplasts, amyloplasts, and etioplasts.IM promoter activity and IM mRNAs are also expressed ubiquitously in Arabidopsis. IM transcript levels correlate with carotenoid accumulation in some, but not all, tissues. This suggests that IM function is not limited to carotenogenesis. Leaf anatomy is radically altered in the green and white sectors ofim: Mesophyll cell sizes are dramatically enlarged in the green sectors and palisade cells fail to expand in the white sectors. The green im sectors also have significantly higher than normal rates of O2 evolution and elevated chlorophyll a/b ratios, typical of those found in “sun” leaves. We conclude that the changes in structure and photosynthetic function of the green leaf sectors are part of an adaptive mechanism that attempts to compensate for a lack of photosynthesis in the white leaf sectors, while maximizing the ability of the plant to avoid photodamage.
Sagittal focusing of high-energy synchrotron X-rays with asymmetric Laue crystals. II. Experimental studies
Authors: Zhong Z. , Kao C. C. , Siddons D. P. , Hastings J. B.
Published: July 2002

The use of bent asymmetric Laue crystals to focus synchrotron X-rays sagittally from 15 to 50 keV is described. A four-bar bender, bending a rectangular planar crystal, produced the necessary sagittal and meridional bending for this unique application. Adjustments of the tilt angle and height of the bent crystal resulted in first- and second-order corrections, respectively, to the dependence of the angle of diffraction on the horizontal position on the crystal. After these corrections, the remaining variation of the diffraction angle was of the order of 10 µrad. The theoretical sagittal focal length was verified. A prototype of a double-crystal sagittally focusing monochromator was constructed and tested, using two identical Laue crystals. A horizontal divergence of 3 mrad was focused to a horizontal dimension of about 0.4 mm. The X-ray flux density at the focus was a few hundred times larger than that of unfocused X-rays.
A new view of conoscopic illumination of optically active crystals
Authors: Geday M. A. , Glazer A. M.
Published: July 2002

Conoscopic illumination is used in a microscope equipped with a rotating polarizer–circular analyser system and monochromatic light, and the resulting interference pattern is separated into its constituent parts. The technique allows identification of the sign of the optical indicatrix and birefringence to be determined without the need to insert extra wave plates. When the technique is applied to an optically active uniaxial crystal, the so-called Airy's spiral is revealed with high sensitivity, enabling the optical rotation of the crystal to be determined unambiguously. Theoretically computed images show a close correspondence with the observed images.
Use of polycapillary X-ray lenses in the X-ray diffraction measurement of texture
Authors: Welzel U. , Leoni M.
Published: July 2002

Corrections for instrumental aberrations of X-ray diffraction texture measurements (pole-figure measurements) conducted in quasi-parallel-beam geometry using an X-ray lens have been investigated on the basis of measurements on (texture-free) reference samples. It has been shown that a defocusing correction, which is a major correction in the case of pole figures recorded with divergent-beam geometries, is not necessary when a parallel beam, produced by an X-ray lens, is used. In this case, the major instrumental sources of error stem from the illumination of areas outside the sample surface,i.e.the finite sample size, and the finite area of the detector, both giving rise to a reduction of the recorded signal. Two correction procedures for this reduction, an experimental one and a numerical one, have been tested and are described.
An approach to rapid protein crystallization using nanodroplets
Authors: Santarsiero B. D. , Yegian D. T. , Lee C. C. , Spraggon G. , Gu J. , Scheibe D. , Uber D. C. , Cornell E. W. , Nordmeyer R. A. , Kolbe W. F. , Jin J. , Jones A. L. , Jaklevic J. M. , Schultz P. G. , Stevens R. C.
Published: July 2002

An approach that enables up to a two order of magnitude reduction in the amount of protein required and a tenfold reduction in the amount of time required for vapor-diffusion protein crystallization is reported. A prototype high-throughput automated system was used for the production of diffraction-quality crystals for a variety of proteins from a screen of 480 conditions using drop volumes as small as 20 nL. This approach results in a significant reduction in the time and cost of protein structure determination, and allows for larger and more efficient screens of crystallization parameter space. The ability to produce diffraction-quality crystals rapidly with minimal quantities of protein enables high-throughput efforts in structural genomics and structure-based drug discovery.
X-ray diffraction data on U3Si
Authors: Boucher R. R.
Published: July 2002

X-ray powder data for the compound U3Si have been obtained from an alloy prepared by arc melting uranium and silicon followed by a 7 day anneal at 800°C. The d spacing determinations have been extended into the back reflection to a 2θ value of 167.4 °. The observed relative intensities are compared with calculated values.
An APL solution for the sphere tangent to four spheres
Authors: Langlet G. A.
Published: July 2002

A differential formulation of the problem of the largest sphere inscribed between n + 1 spheres in a space with n dimensions leads to a linear system of n + 1 equations with n unknowns which can be solved by the least-squares method. This formulation is most efficient for APL computing.
On the determination of the metastable miscibility gap in ternary alloys from small-angle measurements. II. Application to the system Al–Zn–Mg
Authors: Gerold V. , Epperson J. E. , Kostorz G.
Published: July 2002

The method described in the preceding paper [Gerold (1977), J. Appl. Cryst. 10, 25–27] has been applied to the system Al–Zn–Mg where the small-angle scattering has been measured from nine alloys having zinc and magnesium contents up to 5.4 and 2.5 at. %, respectively. The alloys were annealed at room temperature where the metastable equilibrium of GP zone formation is reached after about one month. From combined analysis of the X-ray and neutron results the slopes of the tie-lines have been evaluated in this region of the phase diagram. The further analysis leads to the approximate determination of the miscibility gap limits. The confidence limits of the determination were restricted by it not being possible to make measurements far enough out in the tail of the neutron scattering profile from the small GP zones (diameter less than 30 Å) to allow the background intensity to be separated completely satisfactorily. The ultimate limiting factor for this type of analysis may be the accuracy to which the mean atomic volumes are known.
Crystal data for some molecular complexes of hexamethylenetetramine with phenols
Authors: Tse C.-S. , Wong Y.-S. , Mak T. C. W.
Published: July 2002

Crystal data are reported for molecular compounds of hexamethylenetetramine with phenol (1:1), resorcinol (1:1), hydroquinone (1:1), o-cresol (1 : 1), m-cresol (1:2), p-chlorophenol (1:2), and p-bromophenol (1:2).
The determination of the first-order phase in membrane diffraction using electron density strip models
Authors: Worthington C. R.
Published: July 2002

The problem of assigning the phase to the first-order reflection in membrane diffraction is treated. Biological membrane assemblies with two membranes per unit cell and the special case of lipid bilayers are treated. Phase assignment is dependent on the origin value of the minus fluid or the minus lipid model and on the actual asymmetry of the membranes. The conditions for phase assignment are derived from a study of single- and three-strip electron density models.
X-ray diffraction curves for a system of parallel cylinders with liquid-like order: A model for the diffraction of crazed polymers
Authors: Paredes E. , Colonomos P.
Published: July 2002

As a model for the internal structure of polymer crazes, a system of parallel cylinders with liquid-like order is proposed. X-ray diffraction curves were calculated for such a system with Monte Carlo data for the radial distribution function of the two-dimensional hard-disk fluid at different packing densities. A comparison is made between the present calculations and experimental results of crazed polycarbonate showing a very good agreement. A way of evaluating the average craze fibril diameter with the calculations is also discussed.
Cell volumes of LaPO4–CePO4 solid solutions
Authors: de Biasi R. S. , Fernandes A. A. R. , Oliveira J. C. S.
Published: July 2002

Lattice constants have been determined for solid solutions of the form La
x
Ce1−x
PO4. A plot of the cube root of the unit-cell volume as a function of x shows that this system follows Végard's law.
A synchrotron radiation monochromator suppressing harmonics
Authors: Treimer W. , Hildebrandt G.
Published: July 2002

The use of asymmetric Bragg reflection offers the possibility of separating wavelength bands belonging to a fundamental wavelength and its higher harmonics from each other. This is shown in an example calculated for X-rays. Especially for well collimated synchrotron radiation the subsequent use of symmetric and asymmetric reflections in a double-crystal arrangement results in different large shifts of the reflected peaks. This kind of synchrotron monochromator offers two important improvements with respect to other similar monochromator systems: (a) it is tunable to the harmonics of a fundamental wavelength in a large range, e.g. from 0.4 to 2.7 Å; and (b) it works harmonic free for each wavelength band on top of the Darwin curve.
Crystal structure and the equation of state of thorium monophosphide for pressures up to 50 GPa
Authors: Olsen J. S. , Gerward L. , Benedict U. , Luo H. , Vogt O.
Published: July 2002

High-pressure X-ray diffraction studies have been performed on ThP using synchrotron radiation and a diamond-anvil cell. The bulk modulus B
0 and its pressure derivative B′0 have been determined (B
0 = 137 GPa; B′0 = 5.1). A phase transition from the NaCl structure to the CsCl structure was observed at about 30 GPa.
Developments in the MITHRIL direct methods program. Erratum
Authors: Gilmore C. J. , Brown S. R.
Published: July 2002

Owing to a printer's error, the key reference of the paper by Gilmore & Brown [J. Appl. Cryst. (1988), 21, 571–572] was omitted. The reference is here given in full.
Diffraction from quasi-crystals and disordered twinned aggregates
Authors: Welberry T. R.
Published: July 2002

Following the discovery of systems with diffraction patterns exhibiting icosahedral symmetry by Shechtman, Blecht, Gratias & Cahn [Phys. Rev. Lett. (1984), 53, 1951–1953], which is forbidden in classical crystallography, interest has centred on Penrose tiling and its generalizations as a model for the explanation of these patterns, although Pauling [Nature (London) (1985), 317, 512–514; Phys. Rev. Lett. (1987), 58, 365–368] has proposed an alternative explanation in terms of crystal twinning. In an attempt to reconcile these two points of view a computer algorithm has been developed, following the methods outlined by Wolny, Pytlik & Lebech [J. Phys. C (1988), 21, 2267–2277], to grow a number of different structures which all tile the two-dimensional (2D) plane without defects. With the same two types of basic unit, it is shown that it is possible, on the one hand, to produce structures similar to the Penrose tiling pattern and, on the other, different types of twinned and disordered structures, with a continuous sequence of intermediates. Optical diffraction patterns of these structures have been obtained for comparison with real quasi-crystals.
Silicon photodiode detector for small-angle X-ray scattering
Authors: Jemian P. R. , Long G. G.
Published: July 2002

A photodiode X-ray detector was built to measure small-angle X-ray scattering (SAXS) at a synchrotron-radiation source in conjunction with a double-crystal diffractometer SAXS camera at photon energies between 5 and 11 keV. The photodiode detector response in this energy range is linear at photon counting rates up to 1012 photons s−1 and thus it was not necessary to attenuate the monochromatic X-ray beam with calibrated foils. SAXS data taken with a scintillation counter and the photodiode detector are compared, demonstrating marked improvement in counting statistics, rate of data acquisition and signal-to-noise ratio.
A robust alternative to η refinement for assessing the hand of chiral compounds
Authors: Le Page Y. , Gabe E. J. , Gainsford G. J.
Published: July 2002

Assessment of the hand of chiral molecular compounds by least-squares refinement of a chirality parameter with all reflections is not statistically robust and can lead to incorrect answers due to a single, unnoticed, gross intensity-measurement error. An alternative is described in which the most easily observable Bijvoet differences are derived from the solved structure and remeasured at slow speed and possibly longer wavelength. Errors due to absorption, multiple reflections and anisotropic extinction can be cancelled out in the measurement for the sense of Bijvoet pairs with the proper experimental technique. An estimate of the probability of having derived the wrong hand, based exclusively on the number of remeasurements and the number of contradictions, and therefore insensitive to individual measurement errors, is developed. With this estimate, determination of the hand of compounds with oxygen as the heaviest scatterer is statistically unambiguous with Cu Kα intensity data, and feasible even with Mo Kα data. Consequently, the method can be applied to Cu Kα data for molecules with carbon as the heaviest scatterer. This approach has been automated as the utility BIVOET in the NRCVAX system of programs.
A new polarized target for neutron scattering studies on biomolecules: first results from apoferritin and the deuterated 50S subunit of ribosomes
Authors: Knop W. , Hirai M. , Schink H.-J. , Stuhrmann H. B. , Wagner R. , Zhao J. , Schärpf O. , Crichton R. R. , Krumpolc M. , Nierhaus K. H. , Rijllart A. , Niinikoski T. O.
Published: July 2002

A new polarized target for neutron scattering has been designed by CERN and tested successfully using the reactor FRG-1 at the GKSS Research Centre. The nuclear spins are aligned with respect to the external field – parallel or antiparallel – by dynamic nuclear polarization (DNP). To avoid absorption of neutrons by 3He, the frozen solutions of biomolecules are immersed in liquid 4He which in turn is thermally coupled to the cooling mixture of 3He/4He of the dilution refrigerator. Compared with earlier experiments where the sample had been cooled directly by 3He, the rate of detectable neutrons increased by a factor of 30. Another factor of 30 is due to the installation of the cold source and the beryllium reflector in FRG-1. Polarized neutron scattering from apoferritin in deuterated solvent shows that the proton spin polarization is homogeneous in apoferritin molecules. After saturation of proton nuclear magnetic resonance (NMR), polarized neutron scattering is dominated by deuteron spin contrast. With the deuterated large subunit of E. coli ribosomes, three different basic scattering functions are derived from spin-contrast variation, reflecting the known scattering-length-density distribution of the architecture of rRNA and ribosomal proteins. The planned in situ structure determination of a mRNA fragment is discussed in the light of the present results.
Energy-dispersive diffuse X-ray scattering apparatus
Authors: Reid J. S. , Clackson S. G.
Published: July 2002

A design is presented of apparatus suitable for energy-dispersive diffuse X-ray scattering in which the sample is oriented on a three-circle cradle within a vacuum chamber. The apparatus alignment procedures are discussed and a method given for finding the relevant orientation matrix under the conditions of Laue scattering to a fixed detector. The method also finds the zero positions of the orienter and is not confined to diffuse-scattering applications.
On the determination of accurate intensities from powder diffraction data. II. Estimation of intensities of overlapping reflections
Authors: Jansen J. , Peschar R. , Schenk H.
Published: July 2002

Even the best least-squares algorithm to extract intensities from a powder diagram will not be able to determine the separate intensities of completely overlapping peaks. In this paper a new method (DOREES) is presented to determine these intensities more accurately by applying relations between structure factors derived from direct methods and the Patterson function. The intensities obtained from the least-squares fit are used as a starting set for DOREES. Comparative tests on both artificially generated and real data show that DOREES improves the intensity set considerably.
A direct method of beam-height correction in small-angle X-ray scattering
Authors: Singh M. A. , Ghosh S. S. , Shannon R. F.
Published: July 2002

A direct (i.e. noniterative) method for desmearing the beam-height effect in small-angle X-ray scattering is discussed. The method is applicable to rectangular collimation systems with arbitrary beam-height intensity profiles. The process involves the construction of an upper-triangular matrix of terms containing the resolution information. A straightforward back-substitution process can then be used to determine the ideal pinhole-collimated curve for any experimental curve obtained with the given resolution. The principal advantage of the method lies in its simplicity, which facilitates an examination of the propagation of random errors through the desmearing process. A comparison between the direct method and the iterative approach of Glatter [J. Appl. Cryst. (1974), 7, 147–153] is made to illustrate the efficiency of the technique.
On the orthogonal transformation used for structural comparisons
Authors: Kearsley S. K.
Published: July 2002

Rotation matrices that minimize or maximize the sum of the squared distances between corresponding atoms for two structures are found using a constrained least-squares procedure solved analytically as an eigenvalue problem in quaternion parameters.
Structural Studies of a Series of Organic Non-Linear Optical Materials
Authors: Cole J. C. , Cole J. M. , Cross G. H. , Farsari M. , Howard J. A. K. , Szablewski M.
Published: July 2002

The crystal structures of {4-[bis(diethylamino)methylium]phenyl}dicyanomethanide (I), {4-[cyano(4-methylpiperidyl)methylium]phenyl } dicyanomethanide (II), {4-[cyano(1-pyrrolidinyl)methylium]phenyl}dicyanomethanide (IV) and (Z)-{4-[1,3-dicyano-3-(diethylamino)-2-propenylium]phenyl} dicyanomethanide have been determined by X-ray crystallography. Together with (Z)-{4-[1-cyano-3-(diethylamino)-2-propenylium]phenyl}dicyanomethanide [(III): Cole, J. C., Howard, J. A. K., Cross, G. H. & Szablewski, M. (1995). Acta Cryst. C51, 715–718], these compounds exhibit varying degrees of quinoidal characteristics and yet have predominantly zwitterionic ground state character. The presence of high dipole moments in the crystal can thus be inferred and are substantiated by measurements of high solution-state dipole moments. Negative solvatochromism (hypsochromism on increasing solvent polarity) confirms the zwitterionic character in at least two of the series.
Packing Modes in Nitrobenzene Derivatives. I. The Single Stacks
Authors: André I. , Foces-Foces C. , Cano F. H. , Martinez-Ripoll M.
Published: July 2002

The crystal packing modes of nitrobenzene derivatives, compounds classified as BCLASS = 15 by the Cambridge Structural Database (CSD), have been analysed. Several packing modes have been observed, although two of them, the so-called stacks and pseudo-herringbone, appear as the most populated ones. In 28.4% of the 169 structures that fulfilled the conditions of the search, the molecules are packed to form columns, with the aromatic planes almost parallel. Different ways of stacking within the columns and the way in which these columns pack together to give the whole crystal have been analysed.
Superstructure Determination of PbZrO3
Authors: Yamasaki K. , Soejima Y. , Fischer K. F.
Published: July 2002

By taking into account the effects of domain structures and X-ray absorption, the superstructure of PbZrO3, lead zirconate, has been determined at room temperature. The space group is Pbam with a unit cell of a = 5.8884 (19), b = 11.771 (4) and c = 8.226 (3) Å, with Z = 8. The intensity data were collected using short-wavelength synchrotron X-rays of 0.350 Å; this reduces the linear absorption coefficient to 11.93 mm−1. The structure refinement was performed using only the data of superlattice reflections which are free from ambiguity and resulting from the domain structure; the final R value is 0.047 for 335 unique superlattice reflections. Zr atoms show the antiphase-type displacement along the z axis; oxygen octahedra show tilt of the type a
−
a
−
c
0 using Glazer's [Acta Cryst. (1972), B28, 3384–3392; Acta Cryst. (1975), A31, 756–762] notation.
Graph-set analysis of hydrogen-bond patterns: some mathematical concepts. Erratum
Authors: Grell J. , Bernstein J. , Tinhofer G.
Published: July 2002

Owing to a serious printing error, this article [Grell et al. (1999). Acta Cryst. B55, 1030–1043] was printed incorrectly. Pages 1029–1044 have thus been reprinted and included as a loose insert with this issue of the journal.
Difference Fourier refinement of metaquohemerythrin
Authors: Stenkamp R. E. , Sieker L. C. , Jensen L. H.
Published: July 2002

A model for metaquohemerythrin from Themiste dyscritum has been refined in the crystallographic sense of the term by difference Fourier methods at 2.8 and 2.5 Å resolution. Fourteen cycles of refinement reduced R from an initial value of 0.385 for the 9461 reflections from 10 to 2.8 Å to 0.253 for 16 363 reflections from 10 to 2.5 Å resolution. On the basis of peaks in difference maps, 49 water molecules have been added to the model for a total of 3833 atoms in the asymmetric unit.
Bacillus subtilis regulatory protein GerE
Authors: Ducros Valérie M.-A. , Brannigan James A. , Lewis Richard J. , Wilkinson Anthony J.
Published: July 2002

GerE is the latest-acting of a series of factors which regulate gene expression in the mother cell during sporulation in Bacillus. The gene encoding GerE has been cloned from B. subtilis and overexpressed in Escherichia coli. Purified GerE has been crystallized by the hanging-drop vapour-diffusion method using polyethylene glycol as a precipitant. The small plate-like crystals belong to the monoclinic space group C2 and diffract beyond 2.2 Å resolution with a synchrotron radiation X-ray source.
Databases for Protein–Ligand Complexes
Authors: Hendlich Manfred
Published: July 2002

Recent advances in experimental techniques have led to an enormous explosion of available data about protein–ligand complexes. To exploit the information that is hidden in these large data, collection tools for managing and accessing huge data collections are needed. This paper discusses databases for protein–ligand data which are accessible via the World Wide Web. A strong focus is placed on the ReLiBase database system which is a new three-dimensional database for storing and analysing structures of protein–ligand complexes currently deposited in the Brookhaven Protein Data Bank (PDB). ReLiBase contains efficient query tools for identifying and analysing ligands and protein–ligand complexes. Its application for structure-based drug design is illustrated.
Dimorphism of polyglycine I: structural models for crystal modifications
Authors: Kajava A. V.
Published: July 2002

Re-examination of the known data on crystalline forms of polyglycine reveals that the crystal modification `polyglycine I' has two different three-dimensional structures depending on the molecular weight. Structural models for both low molecular weight (LMW) and high molecular weight (HMW) polyglycine I crystals are described. In the LMW crystal model, the molecules have an unusual extended conformation generated by alternation of two mirror-symmetrical residual conformations along the chain. The molecules are parallel and each chain forms interpeptide hydrogen bonds with four adjacent chains. The structural model for the HMW crystal represents a composition of twinning crystallites. The crystallites themselves consist of antiparallel enantiomorphous chains united by hydrogen bonds to form rippled sheets. Calculations of the diffraction patterns and packing energy show that these polyglycine I structures have a higher level of conformity with the experimental data than previously suggested models. New insight into the structure of the polyglycine associates opens up the possibility of designing improved silk-like and nylon materials.
Crystallization and initial X-ray analysis of rabbit mature sterol carrier protein 2
Authors: Choinowski Thomas , Dyer James H. , Maderegger Bernhard , Winterhalter Kaspar H. , Hauser Helmut , Piontek Klaus
Published: July 2002

Sterol carrier protein 2 (SCP2) is a basic intracellular protein which facilitates the in vitro intermembrane transfer of cholesterol, phospholipids and glycolipids. SCP2 was expressed in Escherichia coli, purified to apparent electrophoretic homogeneity and crystallized. Single crystals were obtained by hanging-drop vapour diffusion using ammonium sulfate as precipitant. These crystals belong to space group P41212 or its enantiomorph, with unit-cell parameters a = b = 57.5, c = 86.5 Å, and have one molecule in the crystallographic asymmetric unit. Intensity data to 1.8 Å resolution were collected from native SCP2 crystals using synchrotron radiation, were processed and scaled with an R
linear = 4.9%.
A highly automated heavy-atom search procedure for macromolecular structures
Authors: Grosse-Kunstleve Ralf W. , Brunger Axel T.
Published: July 2002

A new highly automated heavy-atom search procedure combines a fast Fourier transform translation function, Patterson superposition functions and Patterson correlation refinement. The search procedure can be applied to various native and difference Patterson maps and their statistically weighted averages. The procedure was tested with diffraction data for several crystal structures with up to 30 heavy-atom sites in the asymmetric unit and with minimum Bragg spacings ranging from 3 to 4 Å. In all cases, the correct sites were found with modest computing time.
Data-collection strategies
Authors: Dauter Zbigniew
Published: July 2002

The optimal strategy for collecting X-ray diffraction data from macromolecular crystals is discussed. Two kinds of factors influencing the completeness of data are considered. The first are geometric, arising from the symmetry of the reciprocal lattice and from the experimental setup; they affect quantitatively the completeness of the measured set of reflections. The second concern the quality, or information content, of the recorded intensities of these measured reflections.
Structure of an insulin dimer in an orthorhombic crystal: the structure analysis of a human insulin mutant (B9 Ser→Glu)
Authors: Yao Zhi-Ping , Zeng Zong-Hao , Li Hong-Min , Zhang Ying , Feng You-Min , Wang Da-Cheng
Published: July 2002

The structure of human insulin mutant B9 (Ser→Glu) was determined by an X-ray crystallographic method at 2.5 Å resolution with an R factor of 0.165 under non-crystallographic restraints. The crystals were grown at low pH (<3.8) and belong to the orthorhombic P212121 space group with unit-cell dimensions a = 44.54, b = 46.40, c = 51.85 Å and one dimer per asymmetric unit without further aggregation. The structure in this crystal form can be regarded as a model for a discrete insulin dimer and displays the following features compared with the structure of 2Zn insulin. (i) The overall dimer is expanded and more symmetric. The two A chains are about 2 Å more distant from each other, while the two B chains are about 0.8 Å further apart. Both monomers are more similar to molecule 1 than molecule 2 of the 2Zn insulin dimer. (ii) The dimer structure is stabilized by protonation and neutralization of the carboxyl groups at lower pH and, in addition, by formation of a hydrogen-bond network among the side chains of residues GluB9, HisB13 and HisB10 on the dimer-forming surface of both monomers, resulting from a structural rearrangement. (iii) The B-chain amino-terminal segment is in an open state (O state), i.e. a state different from the well known R and T states found in the insulin hexamer. In the O state, the B-chain N-terminal segment is in an extended conformation and is detached from the rest of the molecule. This conformational state has also been observed in the monomeric crystal structure of despentapeptide (B26–B30) and desheptapeptide (B24–B30) insulin, as well as in the solution structure of an engineered insulin monomer. It suggests that the O state may be the characteristic conformation of insulin in lower aggregation forms and may be relevant to the formation of insulin fibrils. In addition, based on the crystallization process, the smallest possible building blocks of insulin crystal are also discussed.
Crystallization and X-ray diffraction data analysis of human deoxyhaemoglobin A0 fully stripped of any anions
Authors: Seixas F. A. V. , de Azevedo W. F. , Colombo M. F.
Published: July 2002

In this work, initial crystallographic studies of human haemoglobin (Hb) crystallized in isoionic and oxygen-free PEG solution are presented. Under these conditions, functional measurements of the O2-linked binding of water molecules and release of protons have evidenced that Hb assumes an unforeseen new allosteric conformation. The determination of the high-resolution structure of the crystal of human deoxy-Hb fully stripped of anions may provide a structural explanation for the role of anions in the allosteric properties of Hb and, particularly, for the influence of chloride on the Bohr effect, the mechanism by which Hb oxygen affinity is regulated by pH. X-ray diffraction data were collected to 1.87 Å resolution using a synchrotron-radiation source. Crystals belong to the space group P21212 and preliminary analysis revealed the presence of one tetramer in the asymmetric unit. The structure is currently being refined using maximum-likelihood protocols.
Crystallization and preliminary X-ray structure determination of Lupinus luteus PR10 protein
Authors: Biesiadka Jacek , Sikorski Michał M. , Bujacz Grzegorz , Jaskólski Mariusz
Published: July 2002

The pathogenesis-related protein of the PR10 class from Lupinus luteus (yellow lupin), LlPR10.1A, is constitutively expressed in roots. It is also accumulated in leaves treated with a suspension of pathogenic bacteria as a response to stress. Recombinant yellow-lupin LlPR10.1A protein has been overexpressed in Escherichia coli as a fusion product with maltose-binding protein. LlPR10.1A crystallizes in the orthorhombic P212121 space group and the crystals diffract to 2.45 Å resolution. The structure has been solved by molecular replacement, using the structure of a birch-pollen allergen protein as a model.
New cationic surfactant as corrosion inhibitor for mild steel in hydrochloric acid solutions
Authors: Abdel Hamid Z. , Soror T.Y. , El‐Dahan H.A. , Omar A.M.A.
Published: July 2002

The inhibiting effect of cationic surfactant N, N, N‐dimethyl 4‐methylbenzyl dodecyl ammonium chloride on mild steel in hydrochloric acid solutions was investigated by surface and thermodynamic measurements, weight loss tests, polarization measurements and EDS techniques. The data obtained from surface and thermodynamic measurements with the inhibitor indicate that the area per molecule slightly increases with increasing temperature and both absorption and micellization processes are spontaneous. Weight loss measurement showed that the inhibition efficiencies increased with increasing surfactant concentration and attained a maximum around their critical micelle concentration. Polarization studies reveal that the inhibitor behaves as a mixed type in hydrochloric acid solutions and acted on the cathodic reaction without modifying the mechanism of the hydrogen evolution reaction. EDS measurement showed high coverage of surfactant on the mild steel surface.
Healthier choices in a supermarket
Authors: Närhinen Maria , Nissinen Aulikki , Puska Pekka
Published: July 2002

Supermarkets are potential sites for collaboration between the health sector, food industry and the sales business in health promotion work. In order to establish the possibility of co‐operation between the municipal food control authority and the retail stores, an intervention project was started in one supermarket in Finland. The aim of the project was to encourage the supermarket to take health aspects, especially related to salt and saturated fat, into consideration in their marketing and to find out how the customers react to this project. The intervention was designed as a step‐wise programme with gradually increasing intervention. During the intervention period 600 customers were interviewed. The awareness of the campaign rose steadily up to over 50 percent during the last phase. The reporting of the local newspaper and radio seemed particularly to increase the customers’ awareness. Both the customers and the supermarket workers had a very positive attitude towards the project throughout the intervention. The direct impact of the intervention on reported purchase behaviour was small but the study showed that health promotion work in co‐operation between food control and supermarkets does work. The project could serve as a model for similar larger health promotion projects and might inspire other supermarkets to help their customers make healthier choices.
Quality assurance and the consumer
Authors: Walley Keith , Parsons Stephen , Bland Maggie
Published: July 2002

In recent years, quality assurance schemes have grown considerably in number and scope. Several useful benefits have been claimed for them including their value as marketing advantages. However, there appears to be a paucity of published research to support this claim. This paper, therefore, seeks to substantiate the claim that quality assurance schemes represent useful marketing advantages as well as determining the magnitude of the advantage. The study is based on conjoint analysis as it is argued that this is a more realistic and therefore, appropriate research technique than the direct elicitation approach embodied in simply asking consumers for their opinions concerning quality assurance schemes. The paper concludes that quality assurance is an influence on the consumer decision process for mince beef and in addition provides an indication as to its relative importance. It also speculates on the implications for quality assurance schemes in general.
Implementing personal development plans: a model for trainers,
managers and supervisors
Authors: Higson Moira , Wilson John P.
Published: July 2002

Proposes that the emphasis for personal development is with the new
and existing managers through the use of management development. Notes,
however, that there is also a need to identify those who have management
potential who are at a lower level. States that companies which ignore
this fact are in danger of creating gaps in their management structure.
Examines a major building society′s personal development plan which
increases performance, developing career planning. Concludes that the
benefits have far outweighed the expectations of the building society.
“Healthier” dairy fat using trans‐vaccenic acid
Authors: Jayan Geetha C. , Herbein Joseph H.
Published: July 2002

The purposes of this study were to identify exogenous factors that would depress synthesis of saturated fats and enhance synthesis of unsaturated fats in the dairy cow’s mammary gland. Certain long‐chain exogenous fatty acids are known to modulate endogenous fat synthesis within tissues. We analyzed the effects of two different long‐chain monounsaturated fatty acids, namely oleic acid and trans‐vaccenic acid (TVA), on activities of acetyl‐CoA carboxylase (ACC), fatty acid synthetase (FAS) and stearoyl‐CoA desaturase (SCD) in bovine mammary epithelial cell cultures. The study was done using an established bovine mammary epithelial cell line, the MacT cells. ACC (EC 6.4.1.2) and FAS (EC 2.3.1.85) are two major enzymes involved in biosynthesis of saturated fatty acids in eucaryotic cells. SCD (EC 1.14.99.5) is the enzyme catalyzing the critical committed step in biosynthesis of unsaturated fatty acids from their saturated precursors. Data indicated depression of activity of enzymes responsible for mammary synthesis of saturated fatty acids (ACC and FAS), along with a simultaneous enhancement of mammary desaturase activity, by TVA.
“A whole can of worms!”
Authors: Höpfl Heather , Dawes Frank
Published: July 2002

Originates from a management development programme which was run
for a statutory water authority over a period of two‐and‐a‐half years,
which sought to facilitate a change in management style away from a
directing and controlling paradigm towards a supportive and trust‐based
paradigm. A significant requirement of the programme, as specified by
senior management, was the empowerment of middle management. However,
the implications of this were not fully appreciated by senior management
until late in the programme when issues of control came back into
prominence. Eventually, the programme was curtailed and middle managers
were consequently disillusioned rather than empowered. Offers insights
into the nature of the dynamics of the change process and draws
attention to the phenomenon of senior management resistance to change.
Suggests, however, a more pervasive ambivalence in change management in
general and “empowerment” in particular. This has
significant implications for the regulation and limitation of learning.
Managers’ perceptions of strategic HR change
Authors: Skinner Denise , Mabey Christopher
Published: July 2002

Describes an ongoing research project investigating how human resource strategies are conceived, designed and implemented in organizations as perceived by the managers involved. Data has been gathered using questionnaires completed by 723 managers studying the Open University MBA, over a five‐year period. The evidence shows most HR changes are organization wide and are intended to enhance organizational performance and support the achievement of primary business objectives. Whereas there is clear board level involvement at the initiation and planning stages, the responsibility for implementation is unclear. This absence of clarity, together with the citing of poor communications as the main reason for the failure of change initiatives, raises a number of questions about leadership, vision and direction, which are considered. The evaluation of the initiative is shown to be a difficult area, often involving inappropriate criteria and is perceived as having few links with the business strategy. From the perspective of their managers, it appears that organizations are still not effective in managing HR change and continue to make the same mistakes, despite the theories and prescription available in the literature.
The role of outplacement in redundancy management
Authors: Doherty Noeleen
Published: July 2002

Explores redundancy as a significant and pervasive outcome of organisational change. Argues that the need to manage the redundancy transition has provoked the development of new HRM policies and practices. Highlights that interventions such as outplacement are often used by companies with little rigorous evaluation of their utility or benefit, yet their continued proliferation would suggest that they appear to have assumed intrinsic credibility and value. Maintains that while the pluralist, contingent nature of the organisational change and individual transition issues are recognised, many organisations appear to resort to normative methods when faced with the challenge of managing the human resource issues associated with redundancy. Argues that the pervasive and complex nature of current changes dictates not only the need for a better understanding of the practices that exist but also an exploration of how HRM theory can contribute to and enhance that understanding.
Devolving human resource responsibilities to the line
Authors: Cunningham Ian , Hyman Jeff
Published: July 2002

Alternative hypotheses for the personnel function are presented, based on findings from four case study organisations which have devolved personnel responsibilities from a designated personnel department to line managers. The views of line managers and employees are sought to assess the effects of these changes. The study finds that devolved responsibilities of personnel are formally geared to securing commitment from employees by promoting an integrative culture of employee management through line managers. In practice, though, we find little evidence that personnel has succeeded in catalysing such changes. The case study findings do not point to any clear evidence of a general increase in influence for personnel practitioners following devolution. Tensions exist between line managers and personnel and the function appears to be vulnerable to further contraction. The study concludes that prospects for personnel following devolution are at best uncertain.