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Other Double-Stranded DNA Viruses
Published in Paul Pumpens, Peter Pushko, Philippe Le Mercier, Virus-Like Particles, 2022
Paul Pumpens, Peter Pushko, Philippe Le Mercier
The Rudiviridae virion has a stiff rod shape and measures about 600–900 × 23 nm (Prangishvili 2012f). It is not enveloped and consists of a tube-like superhelix formed by dsDNA of 24.6–35.5 kb and multiple copies of a major capsid protein. At each end, the tube carries plugs, about 50 × 6 nm, to which three tail fibers are anchored. These tail fibers appear to be involved in adsorption onto the host cell surface. The length of the virions is proportional to the size of the packaged viral DNA (Prangishvili 2012f).
Introduction and Review of Biological Background
Published in Luke R. Bucci, Nutrition Applied to Injury Rehabilitation and Sports Medicine, 2020
Collagen structure begins with synthesis of procollagen chains. Procollagen chains are unique to each type of collagen, but are approximately 1055 amino acids in length. Three procollagen chains form a triple helix, which is the basic unit of collagen. Because of the amino acid sequence of collagen, which is mostly a trimer of glycine, a variable amino acid (usually lysine) and proline, each polypeptide chain forms a left-handed helix which can be intertwined with two other chains to form a right-handed triple superhelix (tropocollagen). Tropocollagen is 300 nm in length and around 285,000 Da. Extensive posttranslational modifications ensue, which are dependent on adequate nutrient status, as will be detailed in subsequent chapters. Collagen is glycosylated, and modified proline and lysine residues provide stabilization of the triple helix structure. Cross-linking with other collagen molecules forms collagen microfibrils. Collagen fibrils are formed from further cross-linking of large numbers of microfibrils. Finally, collagen fibers are formed by aggregation of collagen fibrils, which by now are macroscopic in size. Thus, simple chains of amino acids can be amplified into large physical structures.
Biochemistry and Metabolism
Published in John D Firth, Professor Ian Gilmore, MRCP Part 1 Self-Assessment, 2017
John D Firth, Professor Ian Gilmore
Collagen has a helical form that is very different from an alpha-helix. It has a high proportion of proline and hydroxyproline, and nearly every third residue is a glycine. The helix of collagen is more open than that of an alpha-helix and is not stabilised by hydrogen bonding within the helix. Rather, three helical strands are wound around each other to form a superhelix, with hydrogen bonds between the strands.
Collective excitations in α-helical protein structures interacting with the water environment
Published in Electromagnetic Biology and Medicine, 2020
Vasiliy N. Kadantsev, Alexey Goltsov
Note, that the developed model of the α-helix interacting with its environment needs further development to build a more realistic model by considering tertiary interactions of α-helical structures in native proteins. As the α-helical structure is not stable in aqueous solution in the absence of tertiary interactions, our model in the current version can be directly applied to unfolded α-helical structures that are stable in solution. Such stable structures are the α-helical proteins and the α-helical Fs-peptide enriched with polar amino acid residues (e.g., alanine-rich peptides) which are stable in water environment due to shielding of backbone hydrogen bonds from water molecules (Ghosh et al. 2003). These α-helical structures interact with water molecules through only amino acid residues that were considered in our model (section 3). Moreover, α-helical structures form more complex ones stable in the solution such as the coiled-coil ones, supercoils (a superhelix) as well as α-helix barrel structures due to hydrophobic interaction of the non-polar side-chains (Lupas and Bassler 2017). The amphipathic α-helical coiled-coil structures play a significant role in molecular recognition and protein–protein interaction. For example, the leucine zipper (coiled-coil) structures are responsible for recognition and binding of the transcription factors with the DNA promoter regions of about short (~20) nucleotide sequence (Lupas and Bassler 2017). Excitation of the vibrational modes in the superhelices can be applied to explain the molecular recognition mechanism, long-range protein–protein (Fröhlich 1968a), and protein–DNA interaction (Kurian et al. 2018b), (Oldfield et al. 2005).
Universal influenza vaccines: from viruses to nanoparticles
Published in Expert Review of Vaccines, 2018
Ye Wang, Lei Deng, Sang-Moo Kang, Bao-Zhong Wang
HA stalk antigens. By removing the highly immunogenic HA globular head (Figure 2), strong antibody responses can be focused on the conserved HA stalk regions. However, due to its metastable conformation, HA stalks expressed apart from the head subunit will spontaneously adopt the post-fusion conformation. A recombinant HA stalk antigen must be stabilized for proper use as an antigen [95,96]. We optimized the design of HA stalk constructs by blocking the formation of a superhelix involved in virus-cell membrane fusion. This unique design retains conserved conformational and compositional components, ensuring the immunogenicity of the resulting HA stalk recombinant proteins [20].