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Published Crystal Structure (published + crystal_structure)

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Chemistry	100%

Selected Abstracts

Solution structure of a hydrophobic analogue of the winter flounder antifreeze protein

FEBS JOURNAL, Issue 4 2002
Edvards Liepinsh
The solution structure of a synthetic mutant type I antifreeze protein (AFP I) was determined in aqueous solution at pH 7.0 using nuclear magnetic resonance (NMR) spectroscopy. The mutations comprised the replacement of the four Thr residues by Val and the introduction of two additional Lys-Glu salt bridges. The antifreeze activity of this mutant peptide, VVVV2KE, has been previously shown to be similar to that of the wild type protein, HPLC6 (defined here as TTTT). The solution structure reveals an ,,helix bent in the same direction as the more bent conformer of the published crystal structure of TTTT, while the side chain ,1 rotamers of VVVV2KE are similar to those of the straighter conformer in the crystal of TTTT. The Val side chains of VVVV2KE assume the same orientations as the Thr side chains of TTTT, confirming the conservative nature of this mutation. The combined data suggest that AFP I undergoes an equilibrium between straight and bent helices in solution, combined with independent equilibria between different side chain rotamers for some of the amino acid residues. The present study presents the first complete sequence-specific resonance assignments and the first complete solution structure determination by NMR of any AFP I protein. [source]

Crystallization and initial X-ray diffraction studies of scaffolding protein (gp7) of bacteriophage ,29

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 4 2005
Dwight L. Anderson
The Bacillus subtilis bacteriophage ,29 scaffolding protein (gp7) has been crystallized by the hanging-drop vapour-diffusion method at 293,K. Two new distinct crystal forms that both differed from a previously crystallized and solved scaffolding protein were grown under the same conditions. Form I belongs to the primitive tetragonal space group P41212, with unit-cell parameters a = b = 77.13, c = 37.12,Å. Form II crystals exhibit an orthorhombic crystal form, with space group C222 and unit-cell parameters a = 107.50, b = 107. 80, c = 37.34,Å. Complete data sets have been collected to 1.78 and 1.80,Å for forms I and II, respectively, at 100,K using Cu,K, X-rays from a rotating-anode generator. Calculation of a VM value of 2.46,Å3,Da,1 for form I suggests the presence of one molecule in the asymmetric unit, corresponding to a solvent content of 50.90%, whereas form II has a VM of 4.80,Å3,Da,1 with a solvent content of 48.76% and two molecules in the asymmetric unit. The structures of both crystal forms are being determined by the molecular-replacement method using the coordinates of the published crystal structure of gp7. [source]

Polymorphism in iodotris(tri- p -tolylphosphine)silver(I)

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2009
Gertruida J. S. Venter
The reaction of silver(I) iodide with tri(p -tolyl)phosphine in MeCN solution in 1:3 molar ratio yields a polymorph of the complex of the formula [AgI{P(4-MeC6H4)3}3], with the Ag atom in a distorted tetrahedral environment. A polymorphic structure of this complex (a) is compared with previously published crystal structures (b), determined at different temperatures. The two polymorphs are compared using r.m.s. overlay calculations as well as half-normal probability plots. [source]

Structure of human salivary ,-amylase crystallized in a C -centered monoclinic space group

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 2 2006
S. Zoë Fisher
Human salivary ,-amylase (HSA) is a major secretory protein component of saliva and has important biological functions, including the initial digestion of starch. HSA acts as a monomer and mediates the hydrolysis of ,-1,4-glucosidic linkages in oligosaccharides. To date, all published crystal structures of HSA have been crystallized as monomers in space group P212121. Here, the serendipitous purification, crystallization and ultimate structure determination of a HSA non-crystallographic symmetry (NCS) dimer, while attempting to purify human carbonic anhydrase VI (HCA VI) from saliva using an affinity resin for ,-class carbonic anhydrases, is presented. On further investigation, it was shown that HSA could only be copurified using the affinity resin in the presence of HCA VI which is glycosylated and not the non-glycosylated HCA II. The identification of the HSA crystals was carried out by peptide mapping and mass spectrometry. HSA was shown to have crystallized as an NCS dimer in space group C2, with unit-cell parameters a = 150.9, b = 72.3, c = 91.3,Å, , = 102.8°. The NCS dimer crystal structure is reported to 3.0,Å resolution, with a refined Rcryst of 0.228. The structure is compared with the previously reported P212121 monomer structures and the crystal packing and dimer interface are discussed. [source]