984 resultados para biophysics
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"Literature": p. [331]-340.
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Vol. for 2000 accompanied by separate appendix: Alignments of CTL epitopes.
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Mode of access: Internet.
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Thesis (Ph.D.)--University of Washington, 2016-05
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Thesis (Ph.D.)--University of Washington, 2016-06
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Thesis (Ph.D.)--University of Washington, 2016-06
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Thesis (Ph.D.)--University of Washington, 2016-06
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Sparse-matrix sampling using commercially available crystallization screen kits has become the most popular way of determining the preliminary crystallization conditions for macromolecules. In this study, the efficiency of three commercial screening kits, Crystal Screen and Crystal Screen 2 (Hampton Research), Wizard Screens I and II (Emerald BioStructures) and Personal Structure Screens 1 and 2 (Molecular Dimensions), has been compared using a set of 19 diverse proteins. 18 proteins yielded crystals using at least one crystallization screen. Surprisingly, Crystal Screens and Personal Structure Screens showed dramatically different results, although most of the crystallization formulations are identical as listed by the manufacturers. Higher molecular weight polyethylene glycols and mixed precipitants were found to be the most effective precipitants in this study.
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Modifications at the N-terminus of the rabbit CYP4B1 gene resulted in expression levels in Escherichia coli of up to 660 nmol/L. Solubilization of the enzyme from bacterial membranes led to substantial conversion to cytochrome P420 unless alpha-naphthoflavone was added as a stabilizing ligand. Mass spectrometry analysis and Edman sequencing of purified enzyme preparations revealed differential N-terminal post-translational processing of the various constructs expressed. Notably, bacterial expression of CYP4B1 produced a holoenzyme with >98.5% of its heme prosthetic group covalently linked to the protein backbone. The near fully covalently linked hernoproteins exhibited similar rates and regioselectivities of lauric acid hydroxylation to that observed previously for the partially heme processed enzyme expressed in insect cells. These studies shed new light on the consequences of covalent heme processing in CYP4B1 and provide a facile system for future mechanistic and structural studies with the enzyme. (C) 2003 Elsevier Science (USA). All rights reserved.
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Reef-building corals contain host pigments, termed pocilloporins, that function to regulate the light environment of their resident microalgae by acting as a photoprotectant in excessive sunlight. We have determined the crystal structure of an intensely blue, non-fluorescent pocilloporin to 2.2 Angstrom resolution and a genetically engineered fluorescent variant to 2.4 Angstrom resolution. The pocilloporin chromophore structure adopts a markedly different conformation in comparison with the DsRed chromophore, despite the chromophore sequences (Gin-Tyr-Gly) being identical; the tyrosine ring of the pocilloporin chromophore is noncoplanar and in the trans configuration. Furthermore, the fluorescent variant adopted a noncoplanar chromophore conformation. The data presented here demonstrates that the conformation of the chromophore is highly dependent on its immediate environment.
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Biological utilisation of copper requires that the metal, in its ionic forms, be meticulously transported, inserted into enzymes and regulatory proteins, and excess be excreted. To understand the trafficking process, it is crucial that the structures of the proteins involved in the varied processes be resolved. To investigate copper binding to a family of structurally related copper-binding proteins, we have characterised the second Menkes N-terminal domain (MNKr2). The structure, determined using H-1 and N-15 heteronuclear NMR, of the reduced form of MNKr2 has revealed two alpha-helices lying over a single beta-sheet and shows that the binding site, a Cys(X)(2)Cys pair, is located on an exposed loop. H-1-N-15 HSQC experiments demonstrate that binding of Cu(I) causes changes that are localised to conserved residues adjacent to the metal binding site. Residues in this area are important to the delivery of copper by the structurally related Cu(I) chaperones. Complementary site-directed mutagenesis of the adjacent residues has been used to probe the structural roles of conserved residues. (C) 2003 Published by Elsevier Inc.
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The molecular diversity of symbiotic dinoflagellates associated with the widespread western Pacific coral Plesiastrea versipora was explored in order to examine if associations between reef-building corals and symbiotic dinoflagellates change with environment. Several ribosomal DNA genes with different evolutionary rates were used.. including the large subunit (28S), the 5.8S region and the internal transcribed spacers (ITS). The phylogenetic analysis of the 28S and 5.8S rDNA regions indicated that a single endosymbiont species, highly related to one of the species of Symbiodinium in clade C (=Synbiodinium goreaui, Trench et Blank), associates with P. versipora along the Ryukyu Archipelago. The persistence of the same endosymbiont within P. versipora across this wide array of latitudes may be a result of such features as the Kuroshio Current, which brings tropical temperatures as far north as Honshu, Japan. Analysis of the faster evolving ITS rDNA region revealed significant genetic variability within endosymbionts from different populations. This variation was due to a high degree of interpopulation variability, based on the proportion of pairwise variation detected among the populations (0.95% approximately). By comparison with other studies, the results also indicate that some ITS1 haplotypes from P. versipora endosymbionts seem to be widely distributed within the western Pacific Ocean, ranging from the Great Barrier Reef to the northeast of the China Sea.
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Most scleractinian coral species are widely distributed across the tropical and subtropical Indo-Pacific. However, the genetic connectivity between populations of corals separated by large distances (thousands of kilometers) is not well known. We analyzed variability in the nucleotide sequence of the internal transcribed spacer-1 (ITS-1) of the nuclear ribosomal gene unit in the ubiquitous coral Stylophora pistillata, across the western Pacific Ocean. Eight populations from Japan, Malaysia, and the northern and southern Great Barrier Reef (GBR) were studied. Phylogenetic analyses and analysis of molecular variance (AMOVA) clearly revealed that there is panmixia among these coral populations. AMOVA showed that ITS-1 sequence variability was greater within populations (78.37%) than among populations (12.06%). These patterns strongly suggest high levels of connectivity across the species' latitudinal distribution range in the western Pacific, as is seen in many marine invertebrates.
The production, purification and crystallization of a pocilloporin pigment from a reef-forming coral
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Reef-building corals contain fluorescent pigments termed pocilloporins that function by regulating the light environment of coral and acting as a photoprotectant in excessive sunlight. These pocilloporins are related to the monomeric green fluorescent protein and the tetrameric DsRed fluorescent proteins, which have widespread use as biotechnological tools. An intensely blue-coloured pocilloporin, termed Rtms5, was expressed in Escherichia coli, purified and crystallized. Rtms5 was shown to be tetrameric, with deep blue crystals that diffract to 2.2 Angstrom resolution and belong to space group I4(1)22. The colour of this pocilloporin was observed to be sensitive to pH and a yellow (pH 3.5) and a red form (pH 4.5) of Rtms5 were also crystallized. These crystals belong to space group P4(2)22 and diffract to 2.4 Angstrom resolution or better.
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The relationship between spot volume and variation for all protein spots observed on large format 2D gels when utilising silver stain technology and a model system based on mammalian NSO cell extracts is reported. By running multiple gels we have shown that the reproducibility of data generated in this way is dependent on individual protein spot volumes, which in turn are directly correlated with the coefficient of variation. The coefficients of variation across all observed protein spots were highest for low abundant proteins which are the primary contributors to process error, and lowest for more abundant proteins. Using the relationship between spot volume and coefficient of variation we show it is necessary to calculate variation for individual protein spot volumes. The inherent limitations of silver staining therefore mean that errors in individual protein spot volumes must be considered when assessing significant changes in protein spot volume and not global error. (C) 2003 Elsevier Science (USA). All rights reserved.