Protein coating

The viral protein coat, or capsid, is composed of a large number of subunits, the capsomeres. This subunit structure is a fundamental property and is important from a number of aspects. 

In addition to the protein coat, many animal vims particles are surrounded by a hpoprotein envelope which has generally been derived fiom the cytoplasmic membrane of their last host cell. 

Part of contents pertaining to the protein-coated beads is reproduced with permission from our article entitled Protein-embedding technique a potential approach to standardization of immunohistochemistry for formalin-fixed, paraffin-embedded tissue sections published in J. Histochem. Cytochem. 2005,53(9) 1167-1170. 

A bacteriophage (or phage) is a vims, made up of aDNA or RNA core and a protein coat that may infect bacteria. 

FIGURE 1.25 The virus life cycle. Viruses are mobile bits of genetic iuformatiou encapsulated in a protein coat. The genetic material can be either DNA or RNA. Once this genetic material gains entry to its host cell, it takes over the host machinery for macromolecular synthesis and subverts it to the synthesis of viral-specific nucleic acids and proteins. These virus components are then assembled into mature virus particles that are released from the cell. Often, this parasitic cycle of virus infection leads to cell death and disease. 

Virus Any of various submicroscopic pathogens consisting essentially of a core of a single nucleic acid surrounded by a protein coat, having the ability to replicate only inside a living cell. 

Guilbault G, Ngeh-Ngwainbi J, Foley P, et al. 1986. Use of protein coatings on piezoelectric crystals for assay of gaseous pollutants. Anal Chem Symp Ser Electrochem Sens Anal 25 335-341. 

Vibrio (i) Curved, rod-shaped bacterial cell, (ii) Bacterium of the genus Vibrio. Virion Virus particle the virus nucleic acid surrounded by protein coat and in some cases other material. 

Belotserkovskii B.P., Zarling D.A. Peptide nucleic acid (PNA) facilitates multistranded hybrid formation between linear double-stranded DNA targets and RecA protein-coated complementary single-stranded DNA probes. Biochemistry 2002 41 3686-3692. 

Subsequently, similar experiments were done with viral nucleic acids. The pure viral nucleic acid, when added to cells, led to the synthesis of complete virus particles the protein coat was not required. This process is called transfection. More recently, DNA has been used in cell-free extracts to program the synthesis of RNA that functions as the template for the synthesis of proteins characteristic of the DNA 

Fig. 5.21 Cryoelectron micrograph of a single virus-like particle showing the well-defined protein coating of the 12 nm diameter Au nanoparticle (black disk). (Reprinted with permission from [98]. Copyright (2006) American Chemical Society).

Tannic acid is a strong inhibitor of virus particles in vitro. It inactivated both TMV and TMV-RNA by forming noninfectious complexes (1). TMV-RNA was much more sensitive to inactivation than was whole TMV. It would thus appear that tannic acid could possibly inactivate TMV by reacting with either the protein coat or the RNA core. 

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