issue contents
July 1997 issue
Cover illustration: View of interdomain interface of cell adhesion molecule VCAM-D1D2. The two hydrophobic patches (yellow from domain 1 and orange from domain 2) allow the domains to rock back and forth around the `pivot' residue Tyr89. The long C'E loop and FG loop seem to guide the movement. Courtesy of Jia-huai Wang.
research papers
The structure of the lysozyme isolated from the milk of the echidna, an Australian native monotreme, has been refined with data to 1.9 Å resolution. The nature of the calcium binding site is revealed.
PDB reference: 1jug
Orthorhombic crystals from the copper-containing amine oxidase from Hansenula polymorpha contain three dimers of 158 kDa molecular weight per asymmetric unit. A 12-site potassium mercuric iodide derivative was solved by molecular replacement and is being used to determine the structure of the protein by single isomorphous replacement combined with sixfold averaging and solvent flattening.
The γ correction removes residual bias from refined electron density resulting in model structure factors that are each individually independent from their corresponding observed structure-factor amplitudes. This allows straightforward recombination of the two sources of information.
This paper deals with the question of statistical accuracy of the position and width of molecular groups in membranes, determined in a neutron diffraction experiment.
A protocol is described for transferring crystals of phosphoglucomutase, which are quite fragile, from 55% ammonium sulfate to 55% polyethylene glycol. The increase in diffractivity observed at 253 K is described and a possible rationale for this increase is considered.
Structural features of the crystalline enzyme are described; the relationship of many of these to the active site of the enzyme are discussed.
PDB reference: 3pmg
First crystal structures of a blue-copper nitrite reductase in its oxidized and nitrate-complexed form have been determined.
PDB reference: 1nds
The crystal form of ribonuclease A is unusual in that it diffracts well when dehydrated. Nevertheless, the hydrated structure described herein is similar to that found in other crystal forms.
PDB reference: 1bel
Molecular envelope calculation is a critical step in the density-modification procedure. An improved procedure is proposed to evaluate this envelope when the MR phases are biased by the model.
A simple algorithm is described for the identification of spatially contiguous regions in crystallographic envelopes. All sets of points that are globally connected according to a local connectivity criterion are systematically identified during a single sequential pass through the grid points of the envelope map
Protein solubility and crystallization are determined in solution by interaction potentials. The tuning with pH of the interactions, measured with osmotic pressure, small-angle X-ray scattering and quasi-elastic light scattering, gives results for two potentials: a coulombic repulsive and a van der Waals attractive potential.
wARP is a procedure for the improvement and extension of crystallographic phases. It can be applied as a subsequent step to any conventional phasing or map-modification technique. Requirements are native data extending to at least 2.5 Å resolution and a map of reasonable quality. In the presented examples wARP resulted in a dramatically better phase set and subsequent map improvement far beyond what is provided by existing methodology.
short communications
As shown by free-solution capillary electrophoresis, crystals of hen egg-white lysozyme are positively charged because of absorption of H+ when suspended in aqueous acid solution. The ζ potential increases from 8 to 24 mV as the pH decreases from 5.70 to 3.59.
The influenza virus matrix protein M1 has been crystallized. The crystals are in space group P3121 with a = 66.17 and b = 135.30 Å.
The X-ray diffraction data collected from crystals of the electron-transferring flavoprotein from M. elsdenii is consistent with an orthorhombic space group and a very low solvent content.
The crystal structure of apo duck ovotransferrin has been determined. Both lobes are in the open form.
PDB reference: 1aov
Comparison of the partial amino-acid sequence of artocarpin with the known sequence of jacalin and the solution of the crystal structure of the former using the known structure of the latter shows that the two lectins from jackfruit seeds are homologous.
Crystals of the Fab fragment of the tumour-specific antibody PR1A3 diffracting to 2.9 Å, have been obtained by repeated macroseeding.
Crystals of the calcium-bound domain VI of porcine calpain have been obtained in space group P21 by vapor-diffusion methods. Crystals diffract to 1.9 Å resolution. There are two molecules in the asymmetric unit.
The DNA methyltransferase, M.BseCI from B. stearothermophilus methylates the N6 atom of the 3' adenine in the sequence 5'-ATCGAT-3'. M.BseCI crystals difracting to at least 2.5 Å resolution have been obtained and characterized.
Recombinant Δ10 form of staphylokinase crystallizes in orthorhombic space group C221 with unit-cell parameters a = 43.78, b = 59.86 and c = 103.25 Å and one molecule in the asymmetric unit.
RNA guanylyltransferase from Chlorella virus PBCV-1 has been crystallized. Diffraction data have been collected using native, selenomethionine and mercury-derivatized enzyme.
Crystallization of Bacteroides fragilis Zn2+ β-lactamase. Unit-cell dimensions are a = 56.03, b = 43.98 and c = 105.32 Å, β = 112°.
The tetrameric isocitrate lyase from Aspergillus nidulans has been crystallized in space group P42212 with a monomer in the asymmetric unit.
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