排序方式: 共有55条查询结果,搜索用时 15 毫秒
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Jeremy D. Cook Won Jin Cho Timothy L. Stemmler Bhanu P. Jena 《Chemical physics letters》2008,462(1-3):6-9
In this study, we report for the first time that both t-SNAREs and v-SNARE and their complexes in buffered suspension, exhibit defined peaks at CD signals of 208 and 222 nm wavelengths, consistent with a higher degree of helical secondary structure. Surprisingly, when incorporated in lipid membrane, both SNAREs and their complexes exhibit reduced folding. In presence of NSF–ATP, the SNARE complex disassembles, as reflected from the CD signals demonstrating elimination of α-helices within the structure. 相似文献
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Investigation of the copper binding site and the role of histidine as a ligand in riboflavin binding protein 总被引:4,自引:0,他引:4
Smith SR Bencze KZ Russ KA Wasiukanis K Benore-Parsons M Stemmler TL 《Inorganic chemistry》2008,47(15):6867-6872
Riboflavin Binding Protein (RBP) binds copper in a 1:1 molar ratio, forming a distinct well-ordered type II site. The nature of this site has been examined using X-ray absorption and pulsed electron paramagnetic resonance (EPR) spectroscopies, revealing a four coordinate oxygen/nitrogen rich environment. On the basis of analysis of the Cambridge Structural Database, the average protein bound copper-ligand bond length of 1.96 A, obtained by extended x-ray absorption fine structure (EXAFS), is consistent with four coordinate Cu(I) and Cu(II) models that utilize mixed oxygen and nitrogen ligand distributions. These data suggest a Cu-O 3N coordination state for copper bound to RBP. While pulsed EPR studies including hyperfine sublevel correlation spectroscopy and electron nuclear double resonance show clear spectroscopic evidence for a histidine bound to the copper, inclusion of a histidine in the EXAFS simulation did not lead to any significant improvement in the fit. 相似文献
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Bencze KZ Yoon T Millán-Pacheco C Bradley PB Pastor N Cowan JA Stemmler TL 《Chemical communications (Cambridge, England)》2007,(18):1798-1800
The coordinated iron structure and ferrochelatase binding surface of human frataxin have been characterized to provide insight into the protein's ability to serve as the iron chaperone during heme biosynthesis. 相似文献
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Ravhi S. Kumar Sandeep Rekhi D. Prabhakaran M. Somayazulu Eunja Kim Jeremy D. Cook Timothy Stemmler A.T. Boothroyd Mark R. Chance Andrew L. Cornelius 《Solid State Communications》2009,149(39-40):1712-1716
The crystal structure of Na0.75CoO2 was studied at ambient and low temperatures down to 10 K at pressures up to 40 GPa using synchrotron x-rays and a diamond cell in angle dispersion geometry. A reduction in the c/a ratio was observed at both conditions with the application of pressure. An increase in Co–O bond lengths and a decrease in Na–O bond lengths were observed above 10 GPa. The results of the density functional calculations performed agree well with the pressure induced bond length changes. The anomalous change in the c/a ratio and bond lengths indicate a pressure induced isostructural phase transition above 10 GPa. Bulk modulus calculations show this compound is less compressible than its hydrated analogues. 相似文献
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Psomas G Stemmler AJ Dendrinou-Samara C Bodwin JJ Schneider M Alexiou M Kampf JW Kessissoglou DP Pecoraro VL 《Inorganic chemistry》2001,40(7):1562-1570
Assembly reactions that can prepare reliably regioselective metallamacrocyclic complexes have been a target in the development of metallacrowns. To this end, a series of mixed ligand and mixed ligand/mixed metal metallacrowns have been synthesized in high yield and structurally characterized. Two distinct connectivities have been observed in these types of metallacrowns. The monomeric, vacant metallacrown with mixed ligand composition [12-MC(Ni(II)N(Hshi)2(pko)2-4)] (1a) shows the connectivity pattern [-O-Ni-O-N-Ni-N-]2 while the other Ni metallacrowns, [12-MC(Ni(II)N(shi)2(pko)2-4)] (2a) and the coupled [12-MC(Ni(II)N(shi))2(pko)2-4)][12-MC(Ni(II)N(shi))3(pko)-4)] (3a) fused metallacrowns as well as the mixed metal Mn-Ni metallacrown [12-MC(Ni(II)Mn(III)N(shi)2(pko)2-4)] (4a), follow the pattern [-Ni-O-N-]4. Also, three distinct arrangements of the chelate rings around the metal ions have been observed. The syntheses are completely general, allowing for the substitution of different ligands into the metallacrown core. Compounds 1 and 4 show the 6-5-6-5-6-5-6-5 arrangement, compounds 2 and 3(1) the 6-6-5-5-6-6-5-5, and the 3(2) component the 6-6-5-5-6-5-6-5. The obtained structures can be rationalized by balancing the charge at each metal site in the metallacrown. Variable temperature magnetic susceptibility measurements show that exchange interactions for all the compounds are weak and dominantly antiferromagnetic (e.g., 2a gives an exchange coupling of J = -1.2 cm(-1) with g = 2.2). In solution, the metallacrowns are shown to be stable both to decomposition and ligand exchange. 相似文献
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A Jung I Stemmler A Brecht G Gauglitz 《Fresenius' Journal of Analytical Chemistry》2001,371(2):128-136
Sequence-specific detection and quantification of nucleic acids are central steps in many molecular biology procedures which have also been transferred to chip-based procedures. Hybridization-based assays can be used to quantify and discriminate between DNA target sequences down to the level of single base mismatches. Arrays of DNA probes immobilized on a support enable simultaneous testing of multiple sequences of a single sample. DNA arrays can be produced either by in-situ synthesis of oligonucleotides or by immobilization of pre-assembled DNA probes. Covalent and directed immobilization improves the reproducibility and stability of DNA arrays. This is especially interesting with repeated use of transducers or chips. Procedures are described for effective covalent immobilization of pre-assembled amino-linked oligonucleotides, by use of ink-jet techniques, on a modified and heated glass surface, with addressable surface areas ranging from 0.01 mm2 to a few mm2. Almost immediate evaporation of the spotted droplets on the heated surfaces leads to very high surface hybridization capacities. The surfaces are suitable for use with a label-free detection method - reflectometric interference spectroscopy (RIfS). It is shown that hybridization capacity and non-specific interaction at these DNA-surfaces can be characterized by use of RIfS. With a consumption of less than 80 ng mm(-2) oligonucleotide and a specific hybridization capacity of more than 300 fmol mm(-2), the activated aminodextran procedure was usually suitable for setting up a DNA array with label-free detection. Non-specific interactions with random oligomers or protein (ovalbumin) were low. Up to 150 repeated regenerations (stripping) of the surfaces by acid treatment and denaturing agents, and 50 days of storage, have been possible without significant loss of hybridization capacity. 相似文献