The Experts below are selected from a list of 37224 Experts worldwide ranked by ideXlab platform
Samuel H. Gellman - One of the best experts on this subject based on the ideXlab platform.
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Retention of Native Quaternary Structure in Racemic Melittin Crystals.
Journal of the American Chemical Society, 2019Co-Authors: Kathleen W. Kurgan, Adam F. Kleman, Craig A. Bingman, Dale F. Kreitler, Bernard Weisblum, Katrina T. Forest, Samuel H. GellmanAbstract:Racemic crystallography has been used to elucidate the secondary and tertiary Structures of peptides and small proteins that are recalcitrant to conventional crystallization. It is unclear, however, whether racemic crystallography can capture native Quaternary Structure, which could be disrupted by heterochiral associations. We are exploring the use of racemic crystallography to characterize the self-assembly behavior of membrane-associated peptides, very few of which have been crystallized. We report a racemic crystal Structure of the membrane-active peptide melittin; the new Structure allows comparison with a previously reported crystal Structure of L-melittin. The tetrameric assembly observed in crystalline L-melittin has been proposed to represent the tetrameric state detected in solution for this peptide. This tetrameric assembly is precisely reproduced in the racemic crystal, which strengthens the conclusion that the tetramer is biologically relevant. More broadly, these findings suggest that racemic crystallography can provide insight on native Quaternary Structure.
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Retention of Native Quaternary Structure in Racemic Melittin Crystals
2019Co-Authors: Kathleen W. Kurgan, Adam F. Kleman, Craig A. Bingman, Dale F. Kreitler, Bernard Weisblum, Katrina T. Forest, Samuel H. GellmanAbstract:Racemic crystallography has been used to elucidate the secondary and tertiary Structures of peptides and small proteins that are recalcitrant to conventional crystallization. It is unclear, however, whether racemic crystallography can capture native Quaternary Structure, which could be disrupted by heterochiral associations. We are exploring the use of racemic crystallography to characterize the self-assembly behavior of membrane-associated peptides, very few of which have been crystallized. We report a racemic crystal Structure of the membrane-active peptide melittin; the new Structure allows comparison with a previously reported crystal Structure of L-melittin. The tetrameric assembly observed in crystalline L-melittin has been proposed to represent the tetrameric state detected in solution for this peptide. This tetrameric assembly is precisely reproduced in the racemic crystal, which strengthens the conclusion that the tetramer is biologically relevant. More broadly, these findings suggest that racemic crystallography can provide insight on native Quaternary Structure
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an alpha beta peptide helix bundle with a pure beta3 amino acid core and a distinctive Quaternary Structure
Journal of the American Chemical Society, 2009Co-Authors: Michael W Giuliano, W S Horne, Samuel H. GellmanAbstract:Helix bundles are among the most widely studied tertiary and Quaternary structural motifs in proteins. Here we present the crystal Structure of an α/β-peptide foldamer that adopts a tetrameric helix-bundle Quaternary Structure with a hydrophobic core composed solely of β-amino acids. The Structure displays features that are unprecedented among all known helix bundles composed of either α-peptides or peptidic foldamers. The tetramer is characterized by an asymmetry of interaction between neighboring helices, and the side-chain packing within the hydrophobic core differs fundamentally from the knobs-into-holes arrangement typical of most helix bundles.
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an alpha beta peptide helix bundle with a pure beta3 amino acid core and a distinctive Quaternary Structure
Journal of the American Chemical Society, 2009Co-Authors: Michael W Giuliano, Seth W Horne, Samuel H. GellmanAbstract:Helix bundles are among the most widely studied tertiary and Quaternary structural motifs in proteins. Here we present the crystal Structure of an alpha/beta-peptide foldamer that adopts a tetrameric helix-bundle Quaternary Structure with a hydrophobic core composed solely of beta-amino acids. The Structure displays features that are unprecedented among all known helix bundles composed of either alpha-peptides or peptidic foldamers. The tetramer is characterized by an asymmetry of interaction between neighboring helices, and the side-chain packing within the hydrophobic core differs fundamentally from the knobs-into-holes arrangement typical of most helix bundles.
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helix bundle Quaternary Structure from alpha beta peptide foldamers
Journal of the American Chemical Society, 2007Co-Authors: Seth W Horne, Joshua L Price, James L Keck, Samuel H. GellmanAbstract:The function of a protein generally depends on adoption of a specific folding pattern, which in turn is determined by the side chain sequence along the polypeptide backbone. Here we show that the sequence-encoded structural information in peptides derived from yeast transcriptional activator GCN4 can be used to prepare hybrid α/β-peptide foldamers that adopt helix bundle Quaternary Structures. Crystal Structures of two hybrid α/β-peptides are reported along with detailed structural comparison to α-peptides of analogous side chain sequence. There is considerable homology between α- and α/β-peptides at the level of helical secondary Structure, with modest but significant differences in the association geometry of helices in the Quaternary Structure.
Joseph Horwitz - One of the best experts on this subject based on the ideXlab platform.
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alpha crystallin the quest for a homogeneous Quaternary Structure
Experimental Eye Research, 2009Co-Authors: Joseph HorwitzAbstract:Alpha A and alpha B crystallins are key members of the small heat-shock protein family. In addition to being a major structural protein of the lens, they are constitutively found in many other cells, where their function is not completely understood. Alpha B crystallin is also known to be over-expressed in many neurological diseases. To date, all efforts to crystallize alpha A or alpha B have failed. Thus, high-resolution data on the tertiary and Quaternary Structures of alpha crystallin is not available. The main reason for this failure seems to be the polydisperse nature of alpha crystallin. This review deals mainly with the polydisperse properties of alpha crystallin and the influence of post-translational modification, chemical modifications, truncations and mutation on its Quaternary Structure.
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the small heat shock protein αb crystallin has a variable Quaternary Structure
Journal of Molecular Biology, 1998Co-Authors: Dana A Haley, Joseph Horwitz, Phoebe L StewartAbstract:alphaB-crystallin is a major structural protein in the lens that is found in a variety of other tissues and is associated with numerous neurological disorders. It is a member of the small heat-shock protein family and possesses chaperone-like properties. Cryo-electron microscopy has been applied to analyze the Quaternary Structure of human recombinant alphaB-crystallin, which spontaneously forms roughly spherical multimers 8 to 18 nm in diameter. Class-sum images based on nearly 5000 alphaB-crystallin particles reveal the presence of a large central cavity, weak regions of density within the protein shell, and an asymmetric Quaternary Structure. The class-sum images are variable in size and shape, and are suggestive of snapshots of a conformationally flexible assembly. As gel-filtration chromatography reveals a range of molecular masses (650 (+/-140) kDa) for the assembly, the class-sum images were further classified on the basis of total molecular mass. A reconstruction at approximately 4 nm resolution was calculated from the images assigned to 32 subunit (approximately 645 kDa) assemblies. Comparison of class-sum images with reprojections of the reconstruction indicates that the resolution is limited by the variable nature of the assembly. A three-dimensional variance map indicates significant structural divergence within the protein shell and on the outer surface of the particle. Some of the strong variance may correspond to the flexible, exposed C-terminal residues of the alphaB-crystallin monomers. The variable Quaternary Structure of alphaB-crystallin is consistent with the polydisperse size of the assembly and the previously observed subunit exchange between multimers. Thus, we propose that the monomer packing is variable, and that the Quaternary Structure of the assembly is not completely defined. A variable alphaB-crystallin Quaternary Structure may facilitate binding of target proteins in up to stoichiometric ratios.
Michael W Giuliano - One of the best experts on this subject based on the ideXlab platform.
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an alpha beta peptide helix bundle with a pure beta3 amino acid core and a distinctive Quaternary Structure
Journal of the American Chemical Society, 2009Co-Authors: Michael W Giuliano, W S Horne, Samuel H. GellmanAbstract:Helix bundles are among the most widely studied tertiary and Quaternary structural motifs in proteins. Here we present the crystal Structure of an α/β-peptide foldamer that adopts a tetrameric helix-bundle Quaternary Structure with a hydrophobic core composed solely of β-amino acids. The Structure displays features that are unprecedented among all known helix bundles composed of either α-peptides or peptidic foldamers. The tetramer is characterized by an asymmetry of interaction between neighboring helices, and the side-chain packing within the hydrophobic core differs fundamentally from the knobs-into-holes arrangement typical of most helix bundles.
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an alpha beta peptide helix bundle with a pure beta3 amino acid core and a distinctive Quaternary Structure
Journal of the American Chemical Society, 2009Co-Authors: Michael W Giuliano, Seth W Horne, Samuel H. GellmanAbstract:Helix bundles are among the most widely studied tertiary and Quaternary structural motifs in proteins. Here we present the crystal Structure of an alpha/beta-peptide foldamer that adopts a tetrameric helix-bundle Quaternary Structure with a hydrophobic core composed solely of beta-amino acids. The Structure displays features that are unprecedented among all known helix bundles composed of either alpha-peptides or peptidic foldamers. The tetramer is characterized by an asymmetry of interaction between neighboring helices, and the side-chain packing within the hydrophobic core differs fundamentally from the knobs-into-holes arrangement typical of most helix bundles.
Seth W Horne - One of the best experts on this subject based on the ideXlab platform.
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an alpha beta peptide helix bundle with a pure beta3 amino acid core and a distinctive Quaternary Structure
Journal of the American Chemical Society, 2009Co-Authors: Michael W Giuliano, Seth W Horne, Samuel H. GellmanAbstract:Helix bundles are among the most widely studied tertiary and Quaternary structural motifs in proteins. Here we present the crystal Structure of an alpha/beta-peptide foldamer that adopts a tetrameric helix-bundle Quaternary Structure with a hydrophobic core composed solely of beta-amino acids. The Structure displays features that are unprecedented among all known helix bundles composed of either alpha-peptides or peptidic foldamers. The tetramer is characterized by an asymmetry of interaction between neighboring helices, and the side-chain packing within the hydrophobic core differs fundamentally from the knobs-into-holes arrangement typical of most helix bundles.
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helix bundle Quaternary Structure from alpha beta peptide foldamers
Journal of the American Chemical Society, 2007Co-Authors: Seth W Horne, Joshua L Price, James L Keck, Samuel H. GellmanAbstract:The function of a protein generally depends on adoption of a specific folding pattern, which in turn is determined by the side chain sequence along the polypeptide backbone. Here we show that the sequence-encoded structural information in peptides derived from yeast transcriptional activator GCN4 can be used to prepare hybrid α/β-peptide foldamers that adopt helix bundle Quaternary Structures. Crystal Structures of two hybrid α/β-peptides are reported along with detailed structural comparison to α-peptides of analogous side chain sequence. There is considerable homology between α- and α/β-peptides at the level of helical secondary Structure, with modest but significant differences in the association geometry of helices in the Quaternary Structure.
Swapna Ganapathy - One of the best experts on this subject based on the ideXlab platform.
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probing secondary tertiary and Quaternary Structure along with protein cofactor interactions for a helical transmembrane protein complex through 1h spin diffusion with mas nmr spectroscopy
Journal of the American Chemical Society, 2007Co-Authors: Swapna Ganapathy, Adriaan J Van Gammeren, F B Hulsbergen, Huub J M De GrootAbstract:Structure determination of membrane proteins with magic angle spinning NMR is rapidly developing. Probing secondary, tertiary, and Quaternary Structure along with protein−cofactor interactions thro...
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probing secondary tertiary and Quaternary Structure along with protein cofactor interactions for a helical transmembrane protein complex through 1h spin diffusion with mas nmr spectroscopy
Journal of the American Chemical Society, 2007Co-Authors: Swapna Ganapathy, Adriaa J Van Gammere, F Hulsberge, Huub J M De GrooAbstract:Structure determination of membrane proteins with magic angle spinning NMR is rapidly developing. Probing secondary, tertiary, and Quaternary Structure along with protein−cofactor interactions through 1H spin diffusion with MAS NMR is demonstrated for a helical transmembrane model protein complex.
