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Sub-cellular Biochemistry

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https://www.readbyqxmd.com/read/28101874/bioengineered-collagens
#1
Barbara Brodsky, John A M Ramshaw
There is a great deal of interest in obtaining recombinant collagen as an alternative source of material for biomedical applications and as an approach for obtaining basic structural and biological information. However, application of recombinant technology to collagen presents challenges, most notably the need for post-translational hydroxylation of prolines for triple-helix stability. Full length recombinant human collagens have been successfully expressed in cell lines, yeast, and several plant systems, while collagen fragments have been expressed in E...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101873/biomaterials-made-from-coiled-coil-peptides
#2
Vincent Conticello, Spencer Hughes, Charles Modlin
The development of biomaterials designed for specific applications is an important objective in personalized medicine. While the breadth and prominence of biomaterials have increased exponentially over the past decades, critical challenges remain to be addressed, particularly in the development of biomaterials that exhibit highly specific functions. These functional properties are often encoded within the molecular structure of the component molecules. Proteins, as a consequence of their structural specificity, represent useful substrates for the construction of functional biomaterials through rational design...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101872/properties-of-engineered-and-fabricated-silks
#3
Gregor Lang, Heike Herold, Thomas Scheibel
Silk is a protein-based material which is predominantly produced by insects and spiders. Hundreds of millions of years of evolution have enabled these animals to utilize different, highly adapted silk types in a broad variety of applications. Silk occurs in several morphologies, such as sticky glue or in the shape of fibers and can, depending on the application by the respective animal, dissipate a high mechanical energy, resist heat and radiation, maintain functionality when submerged in water and withstand microbial settling...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101871/recombinant-structural-proteins-and-their-use-in-future-materials
#4
Tara D Sutherland, Trevor D Rapson, Mickey G Huson, Jeffrey S Church
Recombinant proteins are polymers that offer the materials engineer absolute control over chain length and composition: key attributes required for design of advanced polymeric materials. Through this control, these polymers can be encoded to contain information that enables them to respond as the environment changes. However, despite their promise, protein-based materials are under-represented in materials science. In this chapter we investigate why this is and describe recent efforts to address this. We discuss constraints limiting rational design of structural proteins for advanced materials; advantages and disadvantages of different recombinant expression platforms; and, methods to fabricate proteins into solid-state materials...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101870/fibrillar-collagens
#5
Jordi Bella, David J S Hulmes
Fibrillar collagens (types I, II, III, V, XI, XXIV and XXVII) constitute a sub-group within the collagen family (of which there are 28 types in humans) whose functions are to provide three-dimensional frameworks for tissues and organs. These networks confer mechanical strength as well as signalling and organizing functions through binding to cellular receptors and other components of the extracellular matrix (ECM). Here we describe the structure and assembly of fibrillar collagens, and their procollagen precursors, from the molecular to the tissue level...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101869/fibrin-formation-structure-and-properties
#6
John W Weisel, Rustem I Litvinov
Fibrinogen and fibrin are essential for hemostasis and are major factors in thrombosis, wound healing, and several other biological functions and pathological conditions. The X-ray crystallographic structure of major parts of fibrin(ogen), together with computational reconstructions of missing portions and numerous biochemical and biophysical studies, have provided a wealth of data to interpret molecular mechanisms of fibrin formation, its organization, and properties. On cleavage of fibrinopeptides by thrombin, fibrinogen is converted to fibrin monomers, which interact via knobs exposed by fibrinopeptide removal in the central region, with holes always exposed at the ends of the molecules...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101868/dystrophin-and-spectrin-two-highly-dissimilar-sisters-of-the-same-family
#7
Olivier Delalande, Aleksander Czogalla, Jean-François Hubert, Aleksander Sikorski, Elisabeth Le Rumeur
Dystrophin and Spectrin are two proteins essential for the organization of the cytoskeleton and for the stabilization of membrane cells. The comparison of these two sister proteins, and with the dystrophin homologue utrophin, enables us to emphasise that, despite a similar topology with common subdomains and a common structural basis of a three-helix coiled-coil, they show a large range of dissimilarities in terms of genetics, cell expression and higher level structural organisation. Interactions with cellular partners, including proteins and membrane phospholipids, also show both strikingly similar and very different behaviours...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101867/myosin-and-actin-filaments-in-muscle-structures-and-interactions
#8
John M Squire, Danielle M Paul, Edward P Morris
In the last decade, improvements in electron microscopy and image processing have permitted significantly higher resolutions to be achieved (sometimes <1 nm) when studying isolated actin and myosin filaments. In the case of actin filaments the changing structure when troponin binds calcium ions can be followed using electron microscopy and single particle analysis to reveal what happens on each of the seven non-equivalent pseudo-repeats of the tropomyosin α-helical coiled-coil. In the case of the known family of myosin filaments not only are the myosin head arrangements under relaxing conditions being defined, but the latest analysis, also using single particle methods, is starting to reveal the way that the α-helical coiled-coil myosin rods are packed to give the filament backbones...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101866/titin-and-nebulin-in-thick-and-thin-filament-length-regulation
#9
Larissa Tskhovrebova, John Trinick
In this review we discuss the history and the current state of ideas related to the mechanism of size regulation of the thick (myosin) and thin (actin) filaments in vertebrate striated muscles. Various hypotheses have been considered during of more than half century of research, recently mostly involving titin and nebulin acting as templates or 'molecular rulers', terminating exact assembly. These two giant, single-polypeptide, filamentous proteins are bound in situ along the thick and thin filaments, respectively, with an almost perfect match in the respective lengths and structural periodicities...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101865/tropomyosin-structure-function-and-interactions-a-dynamic-regulator
#10
Sarah E Hitchcock-DeGregori, Bipasha Barua
Tropomyosin is the archetypal-coiled coil, yet studies of its structure and function have proven it to be a dynamic regulator of actin filament function in muscle and non-muscle cells. Here we review aspects of its structure that deviate from canonical leucine zipper coiled coils that allow tropomyosin to bind to actin, regulate myosin, and interact directly and indirectly with actin-binding proteins. Four genes encode tropomyosins in vertebrates, with additional diversity that results from alternate promoters and alternatively spliced exons...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101864/filamentous-structure-of-hard-%C3%AE-keratins-in-the-epidermal-appendages-of-birds-and-reptiles
#11
R D Bruce Fraser, David A D Parry
The structures of avian and reptilian epidermal appendages, such as feathers, claws and scales, have been modelled using X-ray diffraction and electron microscopy data, combined with sequence analyses. In most cases, a family of closely related molecules makes up the bulk of the appendage, and each of these molecules contains a central β-rich 34-residue segment, which has been identified as the principal component of the framework of the 3.4 nm diameter filaments. The N- and C-terminal segments form the matrix component of the filament/matrix complex...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101863/lessons-from-animal-models-of-cytoplasmic-intermediate-filament-proteins
#12
Jamal-Eddine Bouameur, Thomas M Magin
Cytoplasmic intermediate filaments (IFs) represent a major cytoskeletal network contributing to cell shape, adhesion and migration as well as to tissue resilience and renewal in numerous bilaterians, including mammals. The observation that IFs are dispensable in cultured mammalian cells, but cause tissue-specific, life-threatening disorders, has pushed the need to investigate their function in vivo. In keeping with human disease, the deletion or mutation of murine IF genes resulted in highly specific pathologies...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101862/crystallographic-studies-of-intermediate-filament-proteins
#13
Dmytro Guzenko, Anastasia A Chernyatina, Sergei V Strelkov
Intermediate filaments (IFs), together with microtubules and actin microfilaments, are the three main cytoskeletal components in metazoan cells. IFs are formed by a distinct protein family, which is made up of 70 members in humans. Most IF proteins are tissue- or organelle-specific, which includes lamins, the IF proteins of the nucleus. The building block of IFs is an elongated dimer, which consists of a central α-helical 'rod' domain flanked by flexible N- and C-terminal domains. The conserved rod domain is the 'signature feature' of the IF family...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101861/structural-transition-of-trichocyte-keratin-intermediate-filaments-during-development-in-the-hair-follicle
#14
R D Bruce Fraser, David A D Parry
The intermediate filaments (IF) in trichocyte (hard α-) keratin are unique amongst the various classes of IF in having not one but two topologically-distinct structures. The first is formed at an early stage of hair development in a reducing environment within the cells in the lower part of the follicle. The second structure occurs at a later stage of hair development in the upper part of the follicle, where there is a transition to an oxidizing environment. Crosslinking studies reveal that molecular slippage occurs within the IF upon oxidation and that this results in many cysteine residues lying in near axial alignment, thereby facilitating disulphide bond formation...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101860/the-structure-and-topology-of-%C3%AE-helical-coiled-coils
#15
Andrei N Lupas, Jens Bassler, Stanislaw Dunin-Horkawicz
α-Helical coiled coils constitute one of the most diverse folds yet described. They range in length over two orders of magnitude; they form rods, segmented ropes, barrels, funnels, sheets, spirals, and rings, which encompass anywhere from two to more than 20 helices in parallel or antiparallel orientation; they assume different helix crossing angles, degrees of supercoiling, and packing geometries. This structural diversity supports a wide range of biological functions, allowing them to form mechanically rigid structures, provide levers for molecular motors, project domains across large distances, mediate oligomerization, transduce conformational changes and facilitate the transport of other molecules...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101859/functional-and-structural-roles-of-coiled-coils
#16
Marcus D Hartmann
Coiled coils appear in countless structural contexts, as appendages to small proteins, as parts of multi-domain proteins, and as building blocks of filaments. Although their structure is unpretentious and their basic properties are understood in great detail, the spectrum of functional properties they provide in different proteins has become increasingly complex. This chapter aims to depict this functional spectrum, to identify common themes and their molecular basis, with an emphasis on new insights gained into dynamic aspects...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101858/coiled-coil-design-updated-and-upgraded
#17
Derek N Woolfson
α-Helical coiled coils are ubiquitous protein-folding and protein-interaction domains in which two or more α-helical chains come together to form bundles. Through a combination of bioinformatics analysis of many thousands of natural coiled-coil sequences and structures, plus empirical protein engineering and design studies, there is now a deep understanding of the sequence-to-structure relationships for this class of protein architecture. This has led to considerable success in rational design and what might be termed in biro de novo design of simple coiled coils, which include homo- and hetero-meric parallel dimers, trimers and tetramers...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101857/fibrous-protein-structures-hierarchy-history-and-heroes
#18
John M Squire, David A D Parry
During the 1930s and 1940s the technique of X-ray diffraction was applied widely by William Astbury and his colleagues to a number of naturally-occurring fibrous materials. On the basis of the diffraction patterns obtained, he observed that the structure of each of the fibres was dominated by one of a small number of different types of molecular conformation. One group of fibres, known as the k-m-e-f group of proteins (keratin - myosin - epidermin - fibrinogen), gave rise to diffraction characteristics that became known as the α-pattern...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/27830507/vitamin-a-and-vision
#19
John C Saari
Visual systems detect light by monitoring the effect of photoisomerization of a chromophore on the release of a neurotransmitter from sensory neurons, known as rod and cone photoreceptor cells in vertebrate retina. In all known visual systems, the chromophore is 11-cis-retinal complexed with a protein, called opsin, and photoisomerization produces all-trans-retinal. In mammals, regeneration of 11-cis-retinal following photoisomerization occurs by a thermally driven isomerization reaction. Additional reactions are required during regeneration to protect cells from the toxicity of aldehyde forms of vitamin A that are essential to the visual process...
2016: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/27830506/vitamin-a-as-pkc-co-factor-and-regulator-of-mitochondrial-energetics
#20
Ulrich Hammerling
For the past century, vitamin A has been considered to serve as a precursor for retinoids that facilitate vision or as a precursor for retinoic acid (RA), a signaling molecule that modulates gene expression. However, vitamin A circulates in plasma at levels that far exceed the amount needed for vision or the synthesis of nanomolar levels of RA, and this suggests that vitamin A alcohol (i.e. retinol) may possess additional biological activity. We have pursued this question for the last 20 years, and in this chapter, we unfold the story of our quest and the data that support a novel and distinct role for vitamin A (alcohol) action...
2016: Sub-cellular Biochemistry
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